Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| Mobilisation and remobilisation of a large archetypal pathogenicity island of uropathogenic Escherichia coli in vitro support the role of conjugation for horizontal transfer of genomic islands. | A substantial amount of data has been accumulated supporting the important role of genomic islands (GEIs)--including pathogenicity islands (PAIs)--in bacterial genome plasticity and the evolution of bacterial pathogens. Their instability and the high level sequence similarity of different (partial) islands suggest an exchange of PAIs between strains of the same or even different bacterial species by horizontal gene transfer (HGT). Transfer events of archetypal large genomic islands of enterobact ... | 2011 | 21943043 |
| construction of self-transmissible green fluorescent protein-based biosensor plasmids and their use for identification of n-acyl homoserine-producing bacteria in lake sediments. | many bacteria utilize quorum sensing (qs) systems to communicate with each other by means of the production, release, and response to signal molecules. n-acyl homoserine lactone (ahl)-based qs systems are particularly widespread among the proteobacteria, in which they regulate various functions. it has become evident that ahls can also serve as signals for interspecies communication. however, knowledge on the impact of ahls for the ecology of bacteria in their natural habitat is scarce, due main ... | 2010 | 20675456 |
| interbacterial macromolecular transfer by the campylobacter fetus subsp. venerealis type iv secretion system. | we report here the first demonstration of intra- and interspecies conjugative plasmid dna transfer for campylobacter fetus. gene regions carried by a campylobacter coli plasmid were identified that are sufficient for conjugative mobilization to escherichia coli and c. fetus recipients. a broader functional range is predicted. efficient dna transfer involves the virb9 and vird4 genes of the type iv bacterial secretion system encoded by a pathogenicity island of c. fetus subsp. venerealis. complem ... | 2010 | 21115658 |
| transfer of antibiotic multiresistant plasmid rp4 from escherichia coli to activated sludge bacteria. | in situ transfer of a self-transmissible, antibiotic-multiresistant plasmid rp4 from a laboratory escherichia coli strain c600 to indigenous activated sludge bacteria was investigated using filter mating. the transfer frequency of rp4 from the donor e. coli to the bacteria that was sampled from two wastewater treatment plants was 5.1x10(-2) to 7.5x10(-1) and 4.6x10(-3) to 1.3x10(-2)/potential recipient. the isolated transconjugants showed resistance to ap, km, and tc and the presence of a plasmi ... | 2008 | 18930008 |
| influence of temperature on survival and conjugative transfer of multiple antibiotic-resistant plasmids in chicken manure and compost microcosms. | the aim of this study was to determine if mobile plasmids carrying antibiotic-resistant genes could survive and be transferred in chicken manure maintained under conditions similar to those found in commercial cage layer operations and during composting. escherichia coli j5 harboring a self-transmissible plasmid (rp4) and e. coli c600 harboring a mobile plasmid (pie723) were used as plasmid donors; e. coli cv601 was used as a plasmid recipient. at 23 degrees c both plasmids were transferred to e ... | 2007 | 17369529 |
| interaction of bacteroides fragilis plv22a relaxase and transfer dna with escherichia coli rp4-trag coupling protein. | many bacteroides transfer factors are mobilizable in escherichia coli when coresident with the incp conjugative plasmid rp4, but not f. to begin characterization and potential interaction between bacteroides mobilizable transfer factors and the rp4 mating channel, both mutants and deletions of the dna processing (dtr), mating pair formation (mpf) and trag coupling genes of rp4 were tested for mobilization of bacteroides plasmid plv22a. all 10 mpf but none of the four dtr genes were required for ... | 2007 | 17919288 |
| construction of conjugative gene transfer system between e. coli and moderately thermophilic, extremely acidophilic acidithiobacillus caldus mth-04. | a genetic transfer system for introducing foreign genes to biomining microorganisms is urgently needed. thus, a conjugative gene transfer system was investigated for a moderately thermophilic, extremely acidophilic biomining bacterium, acidithiobacillus caldus mth-04. the broad-host-range incp plasmids rp4 and r68.45 were transferred directly into a. caldus mth-04 from escherichia coli by conjugation at relatively high frequencies. additionally the broad-host-range incq plasmids pjrd215, pvlt33, ... | 2007 | 18051368 |
| potential of predominant activated sludge bacteria as recipients in conjugative plasmid transfer. | we investigated the possibility of conjugative plasmid transfer to the predominant bacteria in activated sludge and the factors influencing the transfer frequency in the activated sludge process. we performed conjugative transfers of a self-transmissible, broad-host-range plasmid rp4 from escherichia coli c600 to activated sludge bacteria by broth mating. most of the activated sludge bacteria tested could acquire plasmid rp4, although the transfer frequencies varied from 8.8 x 10(-7) to 1.3 x 10 ... | 2005 | 16473767 |
| novel mobilizable prokaryotic two-hybrid system vectors for high-throughput protein interaction mapping in escherichia coli by bacterial conjugation. | since its initial description, the yeast two-hybrid (y2h) system has been widely used for the detection and analysis of protein-protein interactions. mating-based strategies have been developed permitting its application for automated proteomic interaction mapping projects using both exhaustive and high-throughput strategies. more recently, a number of prokaryotic two-hybrid (p2h) systems have been developed but, despite the many advantages such escherichia coli-based systems have over the y2h s ... | 2005 | 15687376 |
| peptidoglycan degradation by specialized lytic transglycosylases associated with type iii and type iv secretion systems. | specialized lytic transglycosylases are muramidases capable of locally degrading the peptidoglycan meshwork of gram-negative bacteria. specialized lytic transglycosylase genes are present in clusters encoding diverse macromolecular transport systems. this paper reports the analysis of selected members of the specialized lytic transglycosylase family from type iii and type iv secretion systems. these proteins were analysed in vivo by assaying their ability to complement the dna transfer defect of ... | 2005 | 16272370 |
| conjugative plasmid dna transfer in helicobacter pylori mediated by chromosomally encoded relaxase and trag-like proteins. | one of the striking characteristics of helicobacter pylori is the extensive genetic diversity among clinical isolates. this diversity has been attributed to an elevated mutation rate, impaired dna repair, dna transfer and frequent recombination events. plasmids have also been identified in h. pylori but it remained unknown whether conjugation can contribute to dna transfer between clinical isolates. to examine whether h. pylori possesses intrinsic capability for conjugative plasmid transfer, shu ... | 2005 | 16272373 |
| sequence-specific dna binding determined by contacts outside the helix-turn-helix motif of the parb homolog korb. | the korb protein of the broad-host-range plasmid rp4 acts as a multifunctional regulator of plasmid housekeeping genes, including those responsible for replication, maintenance and conjugation. additionally, korb functions as the parb analog of the plasmid's partitioning system. the protein structure consists of eight helices, two of which belong to a predicted helix-turn-helix motif. each half-site of the palindromic operator dna binds one copy of the protein in the major groove. as confirmed b ... | 2004 | 15170177 |
| genetic organization of the catabolic plasmid pjp4 from ralstonia eutropha jmp134 (pjp4) reveals mechanisms of adaptation to chloroaromatic pollutants and evolution of specialized chloroaromatic degradation pathways. | ralstonia eutropha jmp134 (pjp4) is a useful model for the study of bacterial degradation of substituted aromatic pollutants. several key degrading capabilities, encoded by tfd genes, are located in the 88 kb, self-transmissible, incp-1 beta plasmid pjp4. the complete sequence of the 87,688 nucleotides of pjp4, encoding 83 open reading frames (orfs), is reported. most of the coding sequence corresponds to a well-conserved incp-1 beta backbone and the previously reported tfd genes. in addition, w ... | 2004 | 15186344 |
| antibiotic multiresistance plasmid prsb101 isolated from a wastewater treatment plant is related to plasmids residing in phytopathogenic bacteria and carries eight different resistance determinants including a multidrug transport system. | ten different antibiotic resistance plasmids conferring high-level erythromycin resistance were isolated from an activated sludge bacterial community of a wastewater treatment plant by applying a transformation-based approach. one of these plasmids, designated prsb101, mediates resistance to tetracycline, erythromycin, roxythromycin, sulfonamides, cephalosporins, spectinomycin, streptomycin, trimethoprim, nalidixic acid and low concentrations of norfloxacin. plasmid prsb101 was completely sequen ... | 2004 | 15528650 |
| evidence of increased spread and establishment of plasmid rp4 in the intestine under sub-inhibitory tetracycline concentrations. | the consequences of using anti-microbial agents in a complex ecosystem like the animal intestine can be difficult to predict. we have looked at effects of modulations in growth of competing intestinal bacteria on transfer and establishment of new genetic elements in the intestinal microflora. for this purpose, we used tetracycline, which gradually reduces the growth rate of tetracycline-sensitive bacteria, as the concentration of this drug is increased. the effect of tetracycline on transfer and ... | 2003 | 19719638 |
| a model for bacterial conjugal gene transfer on solid surfaces. | abstract quantitative models of bacterial conjugation are useful tools in environmental risk assessment and in studies of the ecology and evolution of bacterial communities. we constructed a mathematical model for gene transfer between bacteria growing on a solid surface. the model considers that donor and recipient cells will form separate colonies, which grow exponentially until nutrient exhaustion. conjugation occurs when donor and recipient colonies meet, all recipient cells becoming transco ... | 2003 | 19719652 |
| the virb4 family of proposed traffic nucleoside triphosphatases: common motifs in plasmid rp4 trbe are essential for conjugation and phage adsorption. | proteins of the virb4 family are encoded by conjugative plasmids and by type iv secretion systems, which specify macromolecule export machineries related to conjugation systems. the central feature of virb4 proteins is a nucleotide binding site. in this study, we asked whether members of the virb4 protein family have similarities in their primary structures and whether these proteins hydrolyze nucleotides. a multiple-sequence alignment of 19 members of the virb4 protein family revealed striking ... | 2003 | 12533481 |
| a method for allelic replacement in francisella tularensis. | a vector for mutagenesis of francisella tularensis was constructed based on the puc19 plasmid. by inserting the sacb gene of bacillus subtilis, orit of plasmid rp4, and a chloramphenicol resistance gene of shigella flexneri, a vector, ppv, was obtained that allowed specific mutagenesis. a protocol was developed that allowed introduction of the vector into the live vaccine strain, lvs, of f. tularensis by conjugation. as a proof of principle, we aimed to develop a specific mutant defective in exp ... | 2003 | 12770718 |
| plasmid introduction in metal-stressed, subsurface-derived microcosms: plasmid fate and community response. | the nonconjugal incq plasmids pmol187 and pmol222, which contain the metal resistance-encoding genes czc and ncc, were introduced by using escherichia coli as a transitory delivery strain into microcosms containing subsurface-derived parent materials. the microcosms were semicontinuously dosed with an artificial groundwater to set a low-carbon flux and a target metal stress (0, 10, 100, and 1,000 micro m cdcl(2)), permitting long-term community monitoring. the broad-host-range incpalpha plasmid ... | 2003 | 12839785 |
| f factor conjugation is a true type iv secretion system. | the f sex factor of escherichia coli is a paradigm for bacterial conjugation and its transfer (tra) region represents a subset of the type iv secretion system (t4ss) family. the f tra region encodes eight of the 10 highly conserved (core) gene products of t4ss including traaf (pilin), the trabf, -kf (secretin-like), -vf (lipoprotein) and tracf (ntpase), -ef, -lf and tragf (n-terminal region) which correspond to trbcp, -ip, -gp, -hp, -ep, -jp, dp and trblp, respectively, of the p-type t4ss exempl ... | 2003 | 12855161 |
| trag-like proteins of type iv secretion systems: functional dissection of the multiple activities of trag (rp4) and trwb (r388). | trag-like proteins are essential components of type iv secretion systems. during secretion, trag is thought to translocate defined substrates through the inner cell membrane. the energy for this transport is presumably delivered by its potential nucleotide hydrolase (ntpase) activity. trag of conjugative plasmid rp4 is a membrane-anchored oligomer that binds rp4 relaxase and dna. trwb (r388) is a hexameric trag-like protein that binds atp. both proteins, however, lack ntpase activity under in vi ... | 2003 | 12867445 |
| identification of a transmissible plasmid from an argentine sinorhizobium meliloti strain which can be mobilised by conjugative helper functions of the european strain s. meliloti gr4. | we describe in this work the identification and the conjugal properties of two cryptic plasmids present in the strain sinorhizobium meliloti lpu88 isolated from an argentine soil. one of the plasmids, psmelpu88b (22 kb), could be mobilised from different s. meliloti strains to other bacteria by conjugation only if the other plasmid, psmelpu88a (139 kb), was present. this latter plasmid, however, could not be transferred via conjugation (frequency <10(-9) transconjugants per recipient) contrastin ... | 2003 | 12900015 |
| rp4 repressor protein korb binds to the major groove of the operator dna: a raman study. | korb is a member of the parb family of bacterial partitioning proteins. the protein encoded by the conjugative plasmid rp4 is part of the global control circuit and regulates the expression of plasmid genes, the products of which are involved in replication, transfer, and stable inheritance. korb is a homodimeric protein which binds to palindromic 13 bp dna sequences [5'-tttagc((g)/(c))gctaaa-3'] present 12 times in the 60 kb plasmid. each korb subunit is composed of two domains; the c-domain is ... | 2003 | 14661959 |
| molecular cloning of a functional cis-acting, bam hi-flanked, 1.6 kb 'mob' cassette for demonstrating rapid conversion of col ei origin-dna cloning vectors into conjugal form. | a 1.6 kb mobilization (mob) fragment originating from broad host range incp plasmid rp4 is effectively cloned into two different col ei-origin based cloning vectors, pbluescript ii sk+ and pt-adv, to generate ppar-i and ppar-ii, respectively. the vectors have different genetic markers and were demonstrated to get mobilized at significant frequency into a laboratory and an enteroroxigenic strain of escherichia coli with all the genetic markers of the recombinant clones expressing efficiently in t ... | 2002 | 14752985 |
| an src homology 3-like domain is responsible for dimerization of the repressor protein korb encoded by the promiscuous incp plasmid rp4. | korb is a regulatory protein encoded by the conjugative plasmid rp4 and a member of the parb family of bacterial partitioning proteins. the protein regulates the expression of plasmid genes whose products are involved in replication, transfer, and stable inheritance of rp4 by binding to palindromic 13-bp dna sequences (5'-tttagc(g/c)gctaaa-3') present 12 times in the 60-kb plasmid. here we report the crystal structure of korb-c, the c-terminal domain of korb comprising residues 297-358. the stru ... | 2002 | 11711548 |
| the anti-toxin pard of plasmid rk2 consists of two structurally distinct moieties and belongs to the ribbon-helix-helix family of dna-binding proteins. | nmr and cd spectroscopy have been used to characterize, both structurally and dynamically, the 82-amino-acid pard protein of the post-segregational killing module of the broad-host-range plasmid rp4/rk2. pard occurs as a dimer in solution and exercises two different control functions; an autoregulatory function by binding to its own promoter p(parde) and a plasmid-stabilizing function by inhibiting pare toxicity in cells that express pard and pare. analysis of the secondary structure based on th ... | 2002 | 11743881 |
| identification of a chromosomal tra-like region in agrobacterium tumefaciens. | the vird4 gene is one of the virulence genes present on the ptic58 plasmid of agrobacterium tumefaciens. unexpectedly, we found that a pti-free a. tumefaciens strain carried a protein of similar size to the plasmid-encoded vird4 protein which reacted with vird4-specific antibodies. this suggested that this strain may contain a homologue of the vird4 protein. a chromosomal fragment encoding a protein of similar sequence to vird4 was isolated and a 7.8 kilobase region surrounding the gene encoding ... | 2002 | 11919722 |
| genetic analysis of pigment biosynthesis in xanthobacter autotrophicus py2 using a new, highly efficient transposon mutagenesis system that is functional in a wide variety of bacteria. | a highly efficient method of transposon mutagenesis was developed for genetic analysis of xanthobacter autotrophicus py2. the method makes use of a transposon delivery vector that encodes a hyperactive tn 5 transposase that is 1,000-fold more active than the wild-type transposase. in this construct, the transposase is expressed from the promoter of the teta gene of plasmid rp4, which is functional in a wide variety of organisms. the transposon itself contains a kanamycin resistance gene as a sel ... | 2002 | 12189420 |
| sequence analysis and characterization of plasmid psfd10 from salmonella choleraesuis. | the nucleotide sequence of a small plasmid, designated psfd10, is isolated from the vaccine strain salmonella choleraesuis c500 in china, has been determined. this plasmid is 4091 bp long with a total g+c content of 51.4%, which is in the range of salmonella genomic dna. analysis of the complete nucleotide sequence reveals that psfd10 has a high degree of similarity to cole1-type plasmid, having the possible cer and rom genes, and a putative mobilization origin of cole1-type. plasmid psfd10 poss ... | 2002 | 12206756 |
| prevotella intermedia native plasmid can be mobilized by an escherichia coli conjugal incp plasmid. | we have determined the nucleotide sequence of a small prevotella intermedia cryptic plasmid, pyhbi1, which consisted of sequences that were highly homologous to the amino acid sequence of the replication and mobilization proteins found in related organisms. we have also demonstrated that chimeric plasmids derived from this p. intermedia native plasmid can be mobilized between escherichia coli strains by using a broad-host-range e. coli conjugative plasmid, incp plasmid rp4. the results suggest t ... | 2002 | 12206757 |
| two dnab genes are associated with the origin of replication of pqbr55, an exogenously isolated plasmid from the rhizosphere of sugar beet. | plasmid pqbr55 ( approximately 149 kb) represents one of five (groups i-v) genetically distinct transfer proficient, mercury resistance plasmid groups that have been observed in the phytosphere pseudomonad community at a single geographic location in oxford, uk. a 4.9-kb hindiii fragment was cloned from pqbr55 (a group iii plasmid) that facilitates autonomous replication of a narrow host range cloning vector, pkil29, in the non-permissive host pseudomonas putida uwc1. sequencing revealed that th ... | 2002 | 19709280 |
| biomonitoring of pjp4-carrying pseudomonas chlororaphis with trb protein-specific antisera. | the transfer of catabolic genes on conjugative plasmids to indigenous organisms from which they may spread further into the community allows the introduction of new biodegradative pathways for metabolic conversion of pollutants to the community. biomonitoring of incp plasmid pjp4-carrying pseudomonas chlororaphis from the rhizosphere of arabidopsis thaliana was achieved using antisera specific for proteins from the plasmid transfer machinery. antisera were generated that recognized trbc and trbf ... | 2001 | 11846762 |
| [isolation and functional-structural characteristics of bacillus polymyxa rp4::mucts62 transcipients]. | conjugative-like transfer of hybrid plasmid rp4::mucts62 from escherichia coli to plasmid-free bacillus polymyxa was carried out. bacillus transcipients are detected by the markers of kanamycin and tetracyclin resistance rp4 and thermal sensitivity to growth at 40-42 degrees c, determined by prophage mucts62 in the plasmid. the technique of transception using millipore filters on solid media has been improved. for comparison with experimental samples, restriction mapping of the native plasmid in ... | 2001 | 11449802 |
| a relationship between rp4 plasmid acquisition and phenotypic changes in pseudomonas fluorescens r2fn. | the physiological behaviour of pseudomonas fluorescens strain r2fn was compared to that of transconjugants [r2fn(rp4)], and two aggregation phenotypes were identified (agr- and agr+). agr+ phenotype is characterized by the appearance of macroscopic aggregates when cells are growing in liquid media. transconjugants exhibited agr+ phenotype whereas wild type strain represented agr-. evidence is presented to support correlation between agr+ phenotype acquisition and the presence of the broad-host r ... | 2001 | 11520003 |
| identification and characterization of tn4656, a novel class ii transposon carrying a set of toluene-degrading genes from tol plasmid pww53. | it has been reported that the toluene-degrading (xyl) genes from pseudomonas putida plasmid pww53 are able to translocate to broad-host-range drug resistance plasmid rp4, and pww53-4 is one of the smallest rp4 derivatives (h. keil, s. keil, r. w. pickup, and p. a. williams, j. bacteriol. 164:887-895, 1985). our investigation of pww53-4 in this study demonstrated that such a translocated region that is 39 kb long is a transposon. this mobile element, tn4656, was classified as a class ii transposo ... | 2001 | 11591664 |
| antirestriction protein ard (type c) encoded by incw plasmid psa has a high similarity to the "protein transport" domain of trac1 primase of promiscuous plasmid rp4. | the incw plasmid psa contains the gene ard encoding an antirestriction function that is specific for type i restriction and modification systems. the nucleotide sequence of ard was determined and an appropriate polypeptide of about 33 kda was identified in escherichia coli t7 expression system. analysis of deduced amino acid sequence of ard encoded by psa revealed that this protein has no significant similarities with the known ard proteins (arda and ardb types) except the "antirestriction" moti ... | 2000 | 10686096 |
| trag from rp4 and trag and vird4 from ti plasmids confer relaxosome specificity to the conjugal transfer system of ptic58. | plasmid conjugation systems are composed of two components, the dna transfer and replication system, or dtr, and the mating pair formation system, or mpf. during conjugal transfer an essential factor, called the coupling protein, is thought to interface the dtr, in the form of the relaxosome, with the mpf, in the form of the mating bridge. these proteins, such as trag from the incp1 plasmid rp4 (trag(rp4)) and trag and vird4 from the conjugal transfer and t-dna transfer systems of ti plasmids, a ... | 2000 | 10692358 |
| components of the rp4 conjugative transfer apparatus form an envelope structure bridging inner and outer membranes of donor cells: implications for related macromolecule transport systems. | during bacterial conjugation, the single-stranded dna molecule is transferred through the cell envelopes of the donor and the recipient cell. a membrane-spanning transfer apparatus encoded by conjugative plasmids has been proposed to facilitate protein and dna transport. for the incpalpha plasmid rp4, a thorough sequence analysis of the gene products of the transfer regions tra1 and tra2 revealed typical features of mainly inner membrane proteins. we localized essential rp4 transfer functions to ... | 2000 | 10692361 |
| sequence-related protein export ntpases encoded by the conjugative transfer region of rp4 and by the cag pathogenicity island of helicobacter pylori share similar hexameric ring structures. | rp4 trbb, an essential component of the conjugative transfer apparatus of the broad-host-range plasmid rp4, is a member of the pule protein superfamily involved in multicomponent machineries transporting macromolecules across the bacterial envelope. pule-like proteins share several well conserved motifs, most notable a nucleoside triphosphate binding motif (p-loop). helicobacter pylori hp0525 also belongs to the pule superfamily and is encoded by the pathogenicity island cag, involved in the inf ... | 2000 | 10716714 |
| conjugative junctions in rp4-mediated mating of escherichia coli. | the physical association of bacteria during conjugation mediated by the incpalpha plasmid rp4 was investigated. escherichia coli mating aggregates prepared on semisolid medium were ultrarapidly frozen using copper block freezing, followed by freeze substitution, thin sectioning, and transmission electron microscopy. in matings where the donor bacteria contained conjugative plasmids, distinctive junctions were observed between the outer membranes of the aggregates of mating cells. an electron-den ... | 2000 | 10781537 |
| identification and characterization of a native dichelobacter nodosus plasmid, pdn1. | the gram-negative anaerobe dichelobacter nodosus is the primary causative agent of ovine footrot, a mixed bacterial infection of the hoof. we report here the characterization of a novel native plasmid, pdn1, from d. nodosus. sequence analysis has revealed that pdn1 has a high degree of similarity to broad-host-range plasmids belonging, or related, to escherichia coli incompatibility group q. however, in contrast to these plasmids, pdn1 encodes no antibiotic resistance determinants, lacks genes e ... | 2000 | 10783302 |
| [a family of shuttle vectors for lactobacilli and other gram-positive bacteria based on the plasmid plf1311 replicon]. | a set of broad-host-range single-replicon shuttle vectors for cloning nucleotide sequences in gram-positive bacteria (lactobacilli, enterococci, lactococci, bacilli, etc.) was created. the vectors are based on the cryptic plasmid plf1311 from lactobacillus fermentum vkm 1311 belonging to a family of the sigma-type pe194-like plasmids. the vectors can replicate in gram-positive bacteria and escherichia coli. they are stable in many gram-positive bacteria, have small sizes, and allow the selection ... | 2000 | 10808493 |
| cloning and characterization of a tetracycline resistance determinant present in agrobacterium tumefaciens c58. | agrobacterium tumefaciens c58 and its derivatives give rise to spontaneous mutants resistant to tetracycline at a high frequency. we observed that a mutation affecting a trna processing function significantly affected the emergence of such mutants, suggesting that c58 contained a positively acting gene conferring resistance to tetracycline. a cosmid clone conferring resistance to tetracycline in escherichia coli and agrobacterium was isolated from a genomic bank of one such mutant. subcloning, t ... | 1999 | 9882678 |
| monitoring the conjugal transfer of plasmid rp4 in activated sludge and in situ identification of the transconjugants. | a gfpmut3b-tagged derivative of broad host-range plasmid rp4 was used to monitor the conjugative transfer of the plasmid from a pseudomonas putida donor strain to indigenous bacteria in activated sludge. transfer frequencies were determined to be in the range of 4 x 10(-6) to 1 x 10(-5) transconjugants per recipient. in situ hybridisation with fluorescently labeled, rrna-targeted oligonucleotides was used to phylogenetically affiliate the bacteria that had received the plasmid. | 1999 | 10234817 |
| escherichia coli mutants lacking all possible combinations of eight penicillin binding proteins: viability, characteristics, and implications for peptidoglycan synthesis. | the penicillin binding proteins (pbps) synthesize and remodel peptidoglycan, the structural component of the bacterial cell wall. much is known about the biochemistry of these proteins, but little is known about their biological roles. to better understand the contributions these proteins make to the physiology of escherichia coli, we constructed 192 mutants from which eight pbp genes were deleted in every possible combination. the genes encoding pbps 1a, 1b, 4, 5, 6, and 7, ampc, and amph were ... | 1999 | 10383966 |
| conjugative transfer of rp4-orit shuttle vectors from escherichia coli to clostridium perfringens. | a chromosomally integrated copy of the incp plasmid rp4 was shown to mediate the conjugative transfer of shuttle plasmids containing an orit site from escherichia coli to the anaerobic pathogen clostridium perfringens. two versatile shuttle plasmids, pjir1456 and pjir1457, which will be invaluable for the introduction of cloned genes into c. perfringens, were constructed. | 1998 | 9514706 |
| decreased symbiotic effectiveness of rhizobium leguminosarum strains carrying plasmid rp4. | the presence of derivatives of the broad host range plasmid rp4 in strains of rhizobium leguminosarum biovar viciae severely inhibited nitrogen fixation by these strains in nodules on cultivars of pea (pisum sativum). the strains formed small white nodules. yield and total nitrogen values were comparable with those obtained for plants inoculated with a non-nodulating mutant. strains carrying the same derivatives gave rise to nitrogen fixing nodules when inoculated on cultivars of lentils (lens c ... | 1998 | 9570119 |
| ptn5cat: a tn5-derived genetic element to facilitate insertion mutagenesis, promoter probing, physical mapping, cloning, and marker exchange in phytopathogenic and other gram-negative bacteria. | a tn5-derived mobile element has been constructed to identify genes and promoters related to pathogenesis and virulence in pseudomonas syringae pv. phaseolicola. to enhance the rate of mutation this tn5 derivative was constructed carrying a mutant transposase which was placed in cis to the transposable element, but just outside the inverted repeats, therefore eliminating secondary transposition and increasing the stability of the insertion. the new element also contains a promoterless cat (chlor ... | 1998 | 9571137 |
| transfer of plasmid rp4 in the spermosphere and rhizosphere of barley seedling. | transfer of plasmid rp4 to indigenous bacteria in bulk soil could only be detected in soil with nutrient amendment. lack of physiological active donor and recipient cells was apparently one of the limiting factors in un-amended bulk soil. plasmid transfer was detected both in the spermosphere and rhizosphere of barley seedlings. transfer occurred from seed coated donor bacteria (i) to introduced recipient bacteria and (ii) to indigenous bacteria present in soil. plasmid transfer was also detecte ... | 1998 | 9602280 |
| natural competence for dna transformation in helicobacter pylori: identification and genetic characterization of the comb locus. | the gram-negative bacterial pathogen helicobacter pylori, an important aetiological agent of gastroduodenal disease in humans, belongs to a group of bacterial species displaying competence for genetic transformation. here, we describe the comb gene locus of h. pylori involved in dna transformation competence. it consists of a cluster of four tandemly arranged genes with partially overlapping open reading frames, orf2, comb1, comb2 and comb3, constituting a single transcriptional unit. orf2 encod ... | 1998 | 9663688 |
| methods for detection of conjugative plasmid transfer in aquatic environments. | donor and recipient counter selection was evaluated by selecting bacteria that received plasmid rp4 by conjugation on filters and in lake water microcosms. three counter selection systems were compared; (i) use of antibiotic-resistant recipients, (ii) use of an auxotrophic donor, and (iii) use of a donor with chromosomal suicide genes. transfer efficiencies of transconjugants per recipient obtained with the three different counter selection systems in filter-matings were not significantly differ ... | 1998 | 9732536 |
| organisation of the bph gene cluster of transposon tn4371, encoding enzymes for the degradation of biphenyl and 4-chlorobiphenyl compounds. | tn4371 is a 55 kb transposon which encodes enzymes for the degradation of biphenyl and 4-chlorobiphenyl compounds into benzoate and 4-chlorobenzoate derivatives. we constructed a cosmid library of tn4371 dna. the bph genes involved in biphenyl/4-chlorobiphenyl degradation were found to be clustered in the middle of the transposon. sequencing revealed an organisation of the bph genes similar to that previously found in pseudomonas sp. kks102, i.e. the bphegf genes are located upstream of bpha1a2a ... | 1997 | 9037111 |
| the trae gene of plasmid rp4 encodes a homologue of escherichia coli dna topoisomerase iii. | the polypeptide encoded by the plasmid rp4 trae gene shows extensive protein sequence similarity to escherichia coli topb, the gene encoding dna topoisomerase iii (topo iii). the trae gene product has been cloned into a bacteriophage t7-based transient expression system, and the polypeptide has been expressed and purified. the trae protein exhibits topoisomerase activity similar to that of topo iii. relaxation is stimulated by high temperature and low concentrations of mg2+. in addition, similar ... | 1997 | 9235964 |
| biological activity of new aza analogues of quinolones. | a series of novel derivatives of 4h-pyrido[1,2-]pyrimidine, 1,4-dihydro-4-oxo-1,5-naphthyridine and 1,4-dihydro-4-oxo-1,6-naphthyridine were prepared and their biological activity was compared with that of nalidixic acid. the in vitro antibacterial activity of the tested compounds was lower than that of nalidixic acid except for two agents, 1b and 2c, with a higher activity against enterococcus faecalis. the compounds were tested for their ability to cure four plasmids from two species of entero ... | 1997 | 9246761 |
| heavy metal resistant arthrobacter sp.--a tool for studying conjugational plasmid transfer between gram-negative and gram-positive bacteria. | the role of two heavy metal-resistant strains of the gram-positive genus arthrobacter sp. as a tool in studying conjugational plasmid transfer between gram-positive and gram-negative bacteria is described. the high nickel resistance and the cobalt resistance of arthrobacter sp. strain rm1/6 could be transferred to arthrobacter sp. strain ws14. incq plasmids (pkt240, pkt240::czc, pml10) could be mobilized from e. coli into arthrobacter spp. strains; antibiotic (km, ap, tc) and heavy metal (co) re ... | 1997 | 9265744 |
| group ii intron from pseudomonas alcaligenes ncib 9867 (p25x): entrapment in plasmid rp4 and sequence analysis. | pseudomonas alcaligenes ncib 9867 (strain p25x), which grows on 2,5-xylenol and harbours the plasmid rp4, was mated with a plasmid-free derivative of pseudomonas putida ncib 9869, strain ra713, which cannot grow on 2,5-xylenol. some ra713 transconjugants, initially selected on 2,5-xylenol, were found to carry rp4 plasmids that had acquired additional fragments (designated xin) which ranged in size from 2 kb to approximately 26 kb instability of dna inserts in rp4::xin hybrid plasmids was observe ... | 1997 | 9274037 |
| a specific protease encoded by the conjugative dna transfer systems of incp and ti plasmids is essential for pilus synthesis. | traf, an essential component of the conjugative transfer apparatus of the broad-host-range plasmid rp4 (incp), which is located at the periplasmic side of the cytoplasmic membrane, encodes a specific protease. the traf gene products of incp and ti plasmids show extensive similarities to prokaryotic and eukaryotic signal peptidases. mutational analysis of rp4 traf revealed that the mechanism of the proteolytic cleavage reaction resembles that of signal and lexa-like peptidases. among the rp4 tran ... | 1997 | 9294428 |
| the parb protein encoded by the rp4 par region is a ca(2+)-dependent nuclease linearizing circular dna substrates. | the parcba operon, which together with the parde operon constitutes an efficient stabilization system of the broad-host-range plasmid rp4, encodes a 20 kda polypeptide (parb), which exhibits sequence homology to nucleases. the parb protein was overexpressed by means of an inducible tac-promoter system. plate assays with herring sperm dna as substrate provided evidence for nuclease activity. the parb nuclease shows specificity for circular dna substrates and linearizes them regardless of the pres ... | 1997 | 9421913 |
| distribution of restriction enzyme recognition sequences on broad host range plasmid rp4: molecular and evolutionary implications. | incp alpha plasmids, exemplified by rp4, are remarkable for their broad host range. they contain strikingly few cleavage sites for many commonly used type ii restriction enzymes but an overabundance of sites for certain enzymes that target g + c-rich sequences. to identify factors responsible for these distributions, the recently compiled nucleotide sequence of rp4 was analysed to determine the frequency of tetra- and hexanucleotide motifs in the 49 kb plasmid backbone. this is defined as the se ... | 1996 | 8642602 |
| [introduction of mutator phage d3112 of pseudomonas aeruginosa into alcaligenes eutrophus var. metallotollerans (strain ch34)]. | it is demonstrated that the intact genome of a d3112 tranposable phage (tp) of pseudomonas aeruginosa, integrated into a recombinant plasmid rp4 :: d3112, can be transferred by means of conjugation from p. putida ppg1 (rp4npt :: d3112) donor cells into alcaligenes eutrophus var. metallotollerans cells. p. aeruginosa strains are unacceptable as donors because they have a bactericidal effect on a. eutrophus. rp4npt :: d3112 plasmid is stably inherited by a. eutrophus with d3112 being expressed and ... | 1996 | 8647419 |
| mechanisms of initiation and termination reactions in conjugative dna processing. independence of tight substrate binding and catalytic activity of relaxase (trai) of incpalpha plasmid rp4. | the relaxase (trai) of plasmid rp4 (incpalpha) plays a key role in initiation and termination of transfer dna replication during conjugative transmission of the plasmid. trai functions as a dna strand transferase that cleaves a unique phosphodiester bond at nic of the transfer origin. the cleavage reaction consists in a reversible transesterification that leads to transfer of the 5' phosphoryl at nic to the hydroxyl group of trai tyr-22. hence, cleavage results in the covalent attachment of trai ... | 1996 | 8662726 |
| the conjugal transfer system of agrobacterium tumefaciens octopine-type ti plasmids is closely related to the transfer system of an incp plasmid and distantly related to ti plasmid vir genes. | we have determined the dna sequences of two unlinked regions of octopine-type ti plasmids that contain genes required for conjugal transfer. both regions previously were shown to contain sequences that hybridize with tra genes of the nopaline-type ti plasmid ptic58. one gene cluster (designated tra) contains a functional orit site and is probably required for conjugal dna processing, while the other gene cluster (designated trb) probably directs the synthesis of a conjugal pilus and mating pore. ... | 1996 | 8763954 |
| genetic transfer of thermophilic trait from alkalophilic thermophilic bacillus to e.coli. | the genomic library of alkalophilic thermophilic bacillus was constructed in e.coli. a single recombinant [patb 507 i] out of 10,000 colonies showed growth at 50 degrees c, which produced large, opaque and mucilaginous colonies on lb. the imvic biochemical tests suggested that the strain was e.coli, and scanning electron microscopy revealed increased cell length. the plasmid dna from the thermophilic recombinant showed multiple bands. the cured strain showed ampicillin resistance (10 micrograms/ ... | 1996 | 8878525 |
| the tra2 core of the incp(alpha) plasmid rp4 is required for intergeneric mating between escherichia coli and streptomyces lividans. | escherichia coli cells and streptomyces mycelia are able to form close contacts in the absence of a conjugative system which might facilitate intergeneric plasmid transfer without the genes required for mating pair formation (tra2) of the rp4 plasmid. the same tra2 genes found to be essential for rp4 plasmid transfer, rsf1010 mobilization, and donor-specific phage propagation in e. coli were also required for intergeneric transfer between e. coli and streptomyces lividans. | 1996 | 8892846 |
| [creating a system of conjugated chromosome transfer and genetic mapping of vibrio cholerae serogroup o139 chromosomes]. | a conjugational gene transfer system consisting of donor and recipient strains has been developed for genetic analysis of vibrio cholerae 0139 serogroup, a new cholera agent. donor strains constructed using the tn5-mob carrying the origin of transfer (ori t) of plasmid rp4 and helper plasmid prp4-4 were able to perform a directed transfer of chromosomal markers. recipient strains carried mutations in auxotrophic genes as well as in virulence genes. based on this gene transfer system, a genetic m ... | 1996 | 8927057 |
| trbk, a small cytoplasmic membrane lipoprotein, functions in entry exclusion of the incp alpha plasmid rp4. | trbk is the only plasmid-encoded gene product involved in entry exclusion of the broad-host-range plasmid rp4. the corresponding gene, trbk, coding for a protein of 69 amino acid residues maps in the tra2 region within the mating pair formation genes. trbk carries a lipid moiety at the n-terminal cysteine of the mature 47-residue polypeptide. the mutant protein trbkc23g cannot be modified or proteolytically processed but still acts in entry exclusion with reduced efficiency. an 8-amino-acid trun ... | 1996 | 8955288 |
| rp4::mu3a-mediated in vivo cloning and transfer of a chlorobiphenyl catabolic pathway. | chromosomal dna fragments encoding the ability to utilize biphenyl as sole carbon source (bph+) were mobilized by means of plasmid rp4::mu3a from strain jb1 (tentatively identified as burkholderia sp.) to alcaligenes eutrophus ch34 at a frequency of 10(-3) per transferred plasmid. the mobilized dna integrated into the recipient chromosome or was recovered as catabolic prime plasmids. three bph+ prime plasmids were transferred from a. eutrophus to escherichia coli and back to a. eutrophus without ... | 1996 | 8969525 |
| site-specific mutations in the trai relaxase and upstream region of plasmid rp4. | the relaxase of rp4 nicks the double-stranded plasmid at the orit site and binds covalently to dna at the 5' end of the nick. the 80-kda relaxase (trai) is encoded on an operon with several overlapping open reading frames (orfs). the importance in conjugation of a short orf (trax) with a start site overlapping the 5' terminus of trai was investigated, as well as the effects of specific mutations in the relaxase. elimination of trax reduced the transfer efficiency by approximately 50% in several ... | 1995 | 8825378 |
| site-specific deletions of chromosomally located dna segments with the multimer resolution system of broad-host-range plasmid rp4. | the multimer resolution system (mrs) of the broad-host-range plasmid rp4 has been exploited to develop a general method that permits the precise excision of chromosomal segments in a variety of gram-negative bacteria. the procedure is based on the site-specific recombination between two directly repeated 140-bp resolution (res) sequences of rp4 effected by the plasmid-borne resolvase encoded by the para gene. the efficiency and accuracy of the mrs system to delete portions of chromosomal dna fla ... | 1995 | 7798149 |
| new mini-tn5 derivatives for insertion mutagenesis and genetic engineering in gram-negative bacteria. | five mini-tn5 derivatives encoding resistance to km, cm, gm, tc, and sm, coupled with the polylinker of the pbluescriptii plasmid, were constructed. these derivatives are carried by an ampicillin-resistant plasmid that has a conditional origin of replication from plasmid r6k and origin of conjugal transfer from the broad host range plasmid rp4. the new vectors are smaller than those previously described and possess numerous unique restriction sites inside the minitransposons for gene cloning in ... | 1995 | 7497352 |
| the use of two-dimensional gradient plates to investigate the range of conditions under which conjugal plasmid transfer occurs. | gel-stabilized two-dimensional gradient plates were used to study the effects of ph, salt concentration and temperature on the conjugal transfer of plasmid rp4 between strains of escherichia coli and pseudomonas putida. the combinations of ph and salt concentration that permitted conjugation were mapped as a two-dimensional growth area occupied by transconjugants following conjugation. this conjugation domain was less extensive than the areas that supported growth of the parental strains, and sh ... | 1995 | 7582032 |
| positive r plasmid mutator effect on chromosomal mutation to nalidixic acid resistance in nalidixic acid-exposed cultures of escherichia coli. | mutation frequencies to nalidixic acid resistance (15 mg/l in nutrient agar) were determined for derivatives of escherichia coli ab1157 carrying the mutator plasmids r46, r391 or pyd1, or the non-mutator plasmid rp4. frequencies of mutation remained constant in cultures of ab1157(r46) growing exponentially in drug-free broth, at a level about 12-fold higher than in the strain without plasmid. mutation frequencies in cultures of strains ab1157(r391) and ab1157(pyd1) were about three times greater ... | 1995 | 7592173 |
| bacterial conjugation mediated by plasmid rp4: rsf1010 mobilization, donor-specific phage propagation, and pilus production require the same tra2 core components of a proposed dna transport complex. | dna transfer by bacterial conjugation requires a mating pair formation (mpf) system that specifies functions for establishing the physical contact between the donor and the recipient cell and for dna transport across membranes. plasmid rp4 (incp alpha) contains two transfer regions designated tra1 and tra2, both of which contribute to mpf. twelve components are essential for mpf, traf of tra1 and 11 tra2 proteins, trbb, -c, -d, -e, -f, -g, -h, -i, -j, -k, and -l. the phenotype of defined mutants ... | 1995 | 7642506 |
| escherichia coli f plasmid transfers to and replicates within legionella pneumophila: an alternative to using an rp4-based system for gene delivery. | derivatives of the self-transmissible f plasmid of escherichia coli can be introduced into legionella pneumophila by conjugation and maintained within only upon selection. in l. pneumophila. f-based replicons seem to exist as extrachromosomal elements since they were readily lost when f-containing l. pneumophila was grown on nonselective medium. the f-based plasmids were not self-transmissible in l. pneumophila. the mating defect may be due to an inability to form the f pilus since f-containing ... | 1994 | 7899513 |
| promiscuous dna transfer system of agrobacterium tumefaciens: role of the virb operon in sex pilus assembly and synthesis. | conjugative transfer of dna that occurs between bacteria also operates between bacteria and higher organisms. the transfer of dna between gram-negative bacteria requires initial contact by a sex pilus followed by dna traversing four membranes (donor plus recipient) using a transmembrane pore. accumulating evidence suggests that transfer of the t-dna from agrobacterium tumefaciens to plants may also occur via a conjugative mechanism. the virb operon of the ti plasmid exhibits close homologies to ... | 1994 | 7914664 |
| metabolic deprivation: a lead to containment in bacterial releases. | experiments were carried out in non-sterile soil, with or without several substrates (sucrose, citrate, lactose) as energy source, and with or without bacterial inoculates able or unable to utilize these substrates. the bacteria were enterobacter agglomerans, escherichia coli, pseudomonas aeruginosa or pseudomonas aureofaciens; they either did or did not contain plasmid rp4. it was found that sucrose is degraded by the indigenous microflora and/or free soil enzymes to give extracellular glucose ... | 1994 | 7921354 |
| essential motifs of relaxase (trai) and trag proteins involved in conjugative transfer of plasmid rp4. | two essential transfer genes of the conjugative plasmid rp4 were altered by site-directed mutagenesis: trag of the primase operon and trai of the relaxase operon. to evaluate effects on the transfer phenotype of the point mutations, we have reconstituted the rp4 transfer system by fusion of the transfer regions tra1 and tra2 to the small multicopy replicon cold. deletions in trag or trai served to determine the tra phenotype of mutant plasmids by trans complementation. two motifs of trag which a ... | 1994 | 8021214 |
| requirements for mobilization of plasmids rsf1010 and cole1 by the incw plasmid r388: trwb and rp4 trag are interchangeable. | mobilization of plasmid rsf1010 by the incw plasmid r388 requires the genes involved in w pilus synthesis plus trwb. trag of the incp plasmid rp4 can substitute for trwb in rsf1010 mobilization by r388 but not in self-transfer of r388. this result suggests a dual specificity of trwb-like proteins in conjugation. the same genetic requirements were found for r388 to mobilize the unrelated plasmid cole1. | 1994 | 8021231 |
| small mobilizable multi-purpose cloning vectors derived from the escherichia coli plasmids pk18 and pk19: selection of defined deletions in the chromosome of corynebacterium glutamicum. | here we describe small mobilizable vectors based on the escherichia coli plasmids pk18 and pk19. we combined the useful properties of the pk plasmids (e.g., multiple cloning site, lacz alpha fragment, sequencing with m13 primers) with the broad-host-range transfer machinery of plasmid rp4 and a modified sacb gene from bacillus subtilis. the new pk derivatives can be transferred by rp4-mediated conjugation into a wide range of gram- and gram+ bacteria, and should facilitate gene disruption and al ... | 1994 | 8045426 |
| analysis of the multimer resolution system encoded by the parcba operon of broad-host-range plasmid rp4. | the broad-host-range plasmid rp4 encodes a highly efficient partitioning function, termed par, that is capable of stabilizing plasmids in a variety of gram-negative bacteria independently of the nature of the replicon. the mechanism responsible for plasmid stabilization by this locus appears to be a complex system which includes a site-specific recombination system mediating resolution of plasmid multimers. in this report we present a detailed study on this multimer resolution system (mrs). the ... | 1994 | 8057833 |
| conjugal transfer of cosmid dna from escherichia coli to saccharopolyspora spinosa: effects of chromosomal insertions on macrolide a83543 production. | cosmid poj436, containing large inserts of saccharopolyspora spinosa (ss) dna, was transferred by conjugation from escherichia coli to ss an integrated into the chromosome, apparently by homologous recombination, at high frequencies (10(-5) to 10(-4) per recipient). transfer was mediated by the plasmid rp4 (rk2) transfer functions in e. coli, and the rk2 orit function located on poj436 [bierman et al., gene 116 (1992) 43-49]. poj436 lacking ss dna, or containing a small insert (approx. 2 kb) of ... | 1994 | 8063103 |
| the sequence of the mer operon of pmer327/419 and transposon ends of pmer327/419, 330 and 05. | three different, independently isolated mercury-resistance-conferring plasmids, pmer327/419, pmer330 and pmer05, from cultures originating from the river mersey (uk), contain identical regulatory merr genes and transposon ends. the mer determinant from pmer327/419 contains an additional potential orf (orf f) located between merp and mera when compared with the archetypal tn501. although these plasmids confer narrow-spectrum resistance (resistance to hg2+, but not organomercurials) their merr gen ... | 1994 | 8063107 |
| [the phenotype of rpi mutant of pseudomonas aeruginosa phage-transposon d3112 expressed in a heterologous escherichia coli host]. | a clone of escherichia coli ii-16 with unique properties was isolated upon incorporation of hybrid plasmid rp4::d3112 with an integrated genome of phage-transposon d3112 pseudomonas aeruginosa into e. coli c600 cells. the cells of this clone produce viable phage and are not sensitive to growth under low temperatures, which is characteristic of the majority of e. coli (rp4::d3112) clones with the genome of wild type phage. the clone e. coli ii-16 contains phage genome both in an integrated state ... | 1994 | 8188046 |
| plasmid and transposon transfer to thiobacillus ferrooxidans. | the broad-host-range incp plasmids rp4, r68.45, rp1::tn501, and pub307 were transferred to acidophilic, obligately chemolithotrophic thiobacillus ferrooxidans from escherichia coli by conjugation. a genetic marker of kanamycin resistance was expressed in t. ferrooxidans. plasmid rp4 was transferred back to e. coli from t. ferrooxidans. the broad-host-range incq vector pjrd215 was mobilized to t. ferrooxidans with the aid of plasmid rp4 integrated in the chromosome of e. coli sm10. pjrd215 was st ... | 1994 | 8188590 |
| trai, a luxi homologue, is responsible for production of conjugation factor, the ti plasmid n-acylhomoserine lactone autoinducer. | conjugal transfer of the nopaline-type agrobacterium ti plasmid ptic58 is regulated by a transcriptional activator, trar, and a diffusible signal molecule, conjugation factor (cf). cf is a member of a family of substituted homoserine lactones (hsls) that act as coinducers for regulating gene expression in diverse gram-negative bacteria by a mechanism called autoinduction. in vibrio fischeri hsl production is conferred by the luxi gene. homologues of this gene are responsible for hsl production b ... | 1994 | 8197112 |
| concerted action of three distinct domains in the dna cleaving-joining reaction catalyzed by relaxase (trai) of conjugative plasmid rp4. | the trai protein of plasmid rp4 (incp alpha) catalyzes a site- and strand-specific cleaving-joining reaction on form i or single-stranded dna. thus, trai is one of the key components involved in the initiation and termination of horizontal dna transfer by bacterial conjugation. amino acid sequence comparison revealed three motifs in the trai sequence conserved in relaxases from different origins. site-directed mutagenesis of the trai structural gene and application of purified mutant trai protei ... | 1994 | 8300611 |
| recombination of the bph (biphenyl) catabolic genes from plasmid pww100 and their deletion during growth on benzoate. | pseudomonas sp. strain cb406 was isolated from polychlorinated biphenyl-contaminated soil and harbors a nontransmissible plasmid, pww100, of approximately 200 kb which carries the genes required for biphenyl and 4-chlorobiphenyl catabolism. the catabolic phenotype was mobilized following the construction in vivo of a cointegrate plasmid containing functional upper and lower biphenyl operons inserted into the broad-host-range r plasmid rp4. the bph phenotype carried by pww100 was stable in nonsel ... | 1994 | 16349195 |
| exogenous isolation of mobilizing plasmids from polluted soils and sludges. | exogenous plasmid isolation was used to assess the presence of mobilizing plasmids in several soils and activated sludges. triparental matings were performed with escherichia coli (a member of the gamma subgroup of the proteobacteria) as the donor of an incq plasmid (pmol155, containing the heavy metal resistance genes czc: co, zn, and cd), alcaligenes eutrophus (a member of the beta subgroup of the proteobacteria) as the recipient, and indigenous microorganisms from soil and sludge samples as h ... | 1994 | 16349216 |
| characterization of newly isolated plasmids from actinobacillus pleuropneumoniae. | the genetic basis of drug-resistant strains of actinobacillus pleuropneumoniae in japan was studied. the a pleuropneumoniae strains av277 and av281 that belong to serotype 2 were resistant to streptomycin (sm) and sulfonamide (sa). both strains had an 8.1-kilobase (kb) sm-sa plasmid that was previously classified in the h1 group. the av177 (serotype 1) strain was resistant to sm, sa, ampicillin, and kanamycin (km), but did not have any plasmids. the av319 and av324 (serotype 1) strains were resi ... | 1993 | 8317761 |
| site-directed mutations in the relaxase operon of rp4. | mutations were constructed by site-directed mutagenesis in the relaxase operon of the broad-host-range plasmid rp4. the mutations were constructed in smaller plasmids, recombined into the 60-kb rp4 plasmid, and tested for their ability to transfer. the relaxase operon contains the transfer genes traj, trah, and trai, which are involved in nicking at the transfer origin to generate the single strand destined to be transferred to the recipient cell. in the first mutant, the c terminus of trai was ... | 1993 | 8335645 |
| [some developmental features of escherichia coli mu phage in pseudomonas aeruginosa cells]. | in order to determine the replication-transposition (rt) efficiency of escherichia coli phage mu in pseudomonas aeruginosa cells, the change of mu dna copy number after transfer of p. aeruginosa (rp4::mu) from 42 (the condition of rp4::mu plasmid stability and low phage production level in p. aeruginosa) to 30 degrees c (the condition of rp4::mu plasmid instability and higher phage production level in p. aeruginosa) was analysed. it was shown that the temperature shift causes no increase in mu d ... | 1993 | 8370507 |
| relaxase (trai) of incp alpha plasmid rp4 catalyzes a site-specific cleaving-joining reaction of single-stranded dna. | conjugative dna transfer of the self-transmissible broad-host-range plasmid rp4 is initiated by strand- and site-specific cleavage at the nick site (nic) of the transfer origin (orit). cleavage results in covalent attachment of the plasmid-encoded relaxase (trai) to the 5'-terminal 2'-deoxycytidine residue at nic. we demonstrate that tyr22 is the center of the catalytic site of trai, mediating cleavage via formation of a phosphodiester between the dna 5' phosphoryl and the aromatic hydroxyl grou ... | 1993 | 8385350 |
| resistance to cefoperazone-sulbactam in klebsiella pneumoniae: evidence for enhanced resistance resulting from the coexistence of two different resistance mechanisms. | we investigated the in vitro activity and the in vivo efficacy of the beta-lactam-beta-lactamase inhibitor combination cefoperazone-sulbactam against an isogenic series of klebsiella pneumoniae strains. both cefoperazone and cefoperazone-sulbactam were active in vitro against a susceptible clinical strain, and the combination was highly effective in the treatment of rat intra-abdominal abscesses. loss of expression of a 39-kda outer membrane protein resulted in at least a fourfold increase in th ... | 1993 | 8390809 |
| [the effect of certain escherichia coli genes on the appearance of the tcs phenotype, conferred by plasmid rp4 with an integrated genome of the d3112 pseudomonas aeruginosa phage]. | the possibility of the sos system activation caused by introduction of a hybrid plasmid rp4::d3112 (where d3112 is a genome of the transposable phage of pseudomonas aeruginosa) into escherichia coli was examined. it has been shown previously that the presence of this plasmid confers to e. coli a so called tcs phenotype: e. coli (rp4::d3112) forms normal colonies and grows at 42 degrees c but does not divide and becomes filamentous at 30 degrees c, probably because of e. coli dna damages generate ... | 1993 | 8405972 |
| the mating pair formation system of plasmid rp4 defined by rsf1010 mobilization and donor-specific phage propagation. | transfer functions of the conjugative plasmid rp4 (incp alpha) are distributed among distinct regions of the genome, designated tra1 and tra2. by deletion analyses, we determined the limits of the tra1 region, essential for intraspecific escherichia coli matings. the tra1 core region encompasses approximately 5.8 kb, including the genes traf, -g, -h, -i, -j, and -k as well as the origin of transfer. the tram gene product, however, is not absolutely required for conjugation but significantly incr ... | 1993 | 8407818 |
| structure, function, and regulation of the kilb locus of promiscuous plasmid rk2. | the kil-kor regulon of the self-transmissible, broad-host-range plasmid rk2 is a unique network with eight coregulated operons. among the genes encoded by the kil-kor regulon are trfa, which encodes the replication initiator, and several kil loci (kila, kilb, kilc, and kile), each of which is lethal to the host cell in the absence of appropriate negative regulatory elements encoded by the kora, korb, korc, and kore determinants. we have proposed that the functions of the kil loci are related to ... | 1993 | 8468300 |
| versatile suicide vectors which allow direct selection for gene replacement in gram-negative bacteria. | a set of vector plasmids which greatly facilitate gene replacement and reverse genetics in many gram-negative bacteria was constructed. these vectors are based on the p15a origin of replication (ori) and incorporate sacb from bacillus subtilis, which is inducible by sucrose and is lethal when expressed in gram-negative bacteria. the vectors also have a convenient antibiotic-resistance marker (gentamicin resistance) and the lacz alpha system which allows blue/white selection of cloned fragments. ... | 1993 | 8486283 |
| the vird4 gene is required for virulence while vird3 and orf5 are not required for virulence of agrobacterium tumefaciens. | the vird operon of the resident ti plasmid of agrobacterium tumefaciens contains loci involved in t-dna processing and undefined virulence functions. nucleotide sequence of the entire vird operon of ptic58 revealed similarities to the vird operon of the root-inducing plasmid pria4b and to that of the octopine-type plasmid ptia6nc. however, comparative sequence data show that vird of ptic58 is more akin to that of the pria4b than to that of the ptia6nc. t7f10::vird gene fusions were used to gener ... | 1993 | 8231811 |
| site-specific cleavage and joining of single-stranded dna by vird2 protein of agrobacterium tumefaciens ti plasmids: analogy to bacterial conjugation. | as an early stage of plant transformation by agrobacterium tumefaciens, the ti plasmid is nicked at the border sequences that delimit the t-dna. cleavage results in covalent attachment of vird2 to the 5' terminal of the nicked strand by a process resembling initiation of dna transfer that occurs in the donor cell during bacterial conjugation. we demonstrate that this cleavage can be reproduced in vitro: vird2 protein, the border-cleaving enzyme, was overproduced and purified. cleavage assays wer ... | 1993 | 8265585 |
| transfer of plasmid rp4 from escherichia coli k-12 to indigenous bacteria of seawater. | transfer of plasmid rp4 from escherichia coli k-12 donor strain to bacteria isolated from seawater was shown to occur on filters and in sterile seawater incubated at 24 degrees c. ten of 12 seawater isolates tested were recipient active for rp4 when the plasmid transfers were assessed by filter matings. when matings were performed in sterile seawater, seven of the 12 isolates received rp4. in sterile seawater, the transfer of rp4 from e. coli to pseudomonads was more efficient than transfer betw ... | 1993 | 8111533 |