| identification of a membrane protein associated with expression of the surface exclusion region of the f transfer operon. | membrane preparations from radioactively labeled male and female strains of escherichia coli k-12 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. an intensely labeled band corresponding to a protein of molecular weight of 24,000 was readily apparent in preparations from hfr and f-prime strains but not in those from female strains. when preparations from a series of hfr strains containing transfer operon deletions were examined, presence of the band ... | 1977 | 321436 |
| suppression of an escherichia coli dnaa mutation by the integrated r factor r100.1: generation of small plasmids after integration. | we have observed that integration of the r plasmid r100.1 into the chromosome of escherichia coli is associated with the formation of small, covalently closed circular elements. contour length measurements, partial denaturation mapping, and analysis of the deoxyribonucleic acid fragments produced by digestion of one of these, plc1, with the restriction endonuclease ecori indicate that it is the r-determinant element of r100.1. | 1977 | 323231 |
| suppression of an escherichia coli dnaa mutation by the integrated r factor r100.1: origin of chromosome replication during exponential growth. | we have investigated the behavior, during exponential growth, of strains of escherichia coli carrying a dnaa(ts) mutation that has been suppressed by the integration of the f-like r plasmid r100.1. we present evidence showing that replication in these strains proceeds largely from the normal chromosome origin at 30 degrees c, a permissive temperature for the dnaa(ts) gene product, whereas, at 42 degrees c, replication proceeds largely from the integrated plasmid. these conclusions are based on m ... | 1977 | 328481 |
| origin and direction of replication of the drug resistance plasmid r100.1 and of a resistance transfer factor derivative in synchronized cultures. | the origin and direction of replication of the resistance plasmid r100.1 and its resistance transfer factor derivative, par132, were studied by electron microscopy autoradiography of partially denatured molecules and partial denaturation mapping of replicative intermediates. results of these studies indicate the existence of an origin of replication at 8.8 kilobases on the r100 map. replication from this origin in cultures synchronized for initiation of replication is predominantly unidirectiona ... | 1977 | 330504 |
| involvement of is1 in the dissociation of the r-determinant and rtf components of the plasmid r100.1. | the formation of the r-determinant plc1 and of the rtf par132 from the composite plasmid r100.1 was investigated. the general location of is1 sequences on the three plasmids was established by hybridization of lambdar14 cii::is1 dna to ecori generated fragments of the various plasmids separated by agarose gel electrophoresis and transferred directly to nitrocellulose filters. the position of is1 sequences on these fragments and the homologies between fragments were analyzed by electron microscop ... | 1977 | 331072 |
| effects of antibiotic resistance plasmids on the bactericidal activity of normal rabbit serum. | the ability of normal rabbit serum to kill escherichia coli j6-2 was measured. with the concentration of serum adjusted so that approximately 2% of the cells survived after 2 h of incubation, there was no killing of the same strain bearing the f-like plasmid r100. other f-like plasmids also provided the host strain with resistance to serum bactericidal activity, whereas none of the i-like plasmids used provided the host strain with resistance. when e. coli j6-2 bore both r100 and an i-like plasm ... | 1978 | 346487 |
| properties of lambda transducing bacteriophages carrying r100 plasmid dna: mercury resistance genes. | three lambdamer (resistance to hg2+ and mercurials) transducing phages were prepared from three independent cointegrate isolates of bacteriophage lambda and plasmid r100. dna heteroduplex and restriction nuclease analyses of the lambdamer dna showed that all three phages had resulted from lambda insertion at kilobase coordinate 8.6 of plasmid r100, followed by loss of different lengths of lambda dna and replacement with different lengths of r100 dna. two of the lambdamer phages were defective, c ... | 1978 | 363687 |
| the contruction and replication properties of hybrid plasmids composed of the r-determinant of r100.1 and the plasmids pcri and psc201. | we have cloned the entire r-determinant of the antibiotic resistance plasmid r100.1 on the plasmic vectors pcr1 and psc201. we find that the hybrid plasmids segregate from cultures in which replication of the vector is blocked. this suggests that the r-det is not capable of autonomous replication. | 1979 | 374994 |
| tn10 mediated integration of the plasmid r100.1 into the bacterial chromosome: inverse transposition. | upon integration into the bacterial chromosome the drug resistance plasmid r100.1 often loses its tetracycline resistance character. we have analyzed an hfr strain formed by such an integration and an r-prime plasmid derived from it. we find that integration took place within the tn10 transposon, that the two is10 sequences were retained, but that at least 80% of the transposon segment located between them, and carrying the tetracycline resistance genes, had been lost. we suggest that integratio ... | 1979 | 381840 |
| transposon a-generated mutations in the mercuric resistance genes of plasmid r100-1. | a series of 23 transposon 801(tn801)-induced mutations of plasmid r100-1 from mercuric salts resistance to sensitivity was studied. although tn801 transposed frequently into the mer region of the plasmid, fine structural analysis showed that the site of insertion within mer varied. about one-half of the tn801 insertion events also caused a deletion of greater than 1 megadalton. genetic and restriction endonuclease ecori and bamhi analysis of the mutant plasmid deoxyribonucleic acid elucidated th ... | 1979 | 387721 |
| deletions in the r-determinant mer region of plasmid r100-1 selected for loss of mercury hypersensitivy. | a mutant of plasmid r100-1, which conferred cellular hypersensitivity to hg2+ because of the insertion of tn801 (tna) into the gene determining synthesis of mercuric reductase enzyme, allowed further mutational events to be selected which resulted in either reversion to hg2+ resistance (characteristic plasmid r100-1) or sensitivity at a level characteristic of plasmidless strains. restriction endonuclease ecori and bamhi analysis showed that reversion to resistance resulted from loss of tna from ... | 1979 | 387727 |
| direction of deoxyribonucleic acid transfer and replication in a derivative of plasmid r100-1. | the site of integration and the molecular orientation of a prophage mu integrated within the resistance transfer factor component of plasmid r100-1 have been determined on the physical map of the plasmid. this allowed us (i) to determine the direction of deoxyribonucleic acid transfer from orit during conjugation and (ii) to demonstrate the unidirectionality of replication in conditions of exponential growth (by determining the strand preference of mu-specific okazaki fragments). | 1979 | 391800 |
| plasmid-mediated resistance to the bactericidal effects of normal rabbit serum. | an escherichia coli k-12 strain bearing the plasmids r1 or r100 was more resistant to the bactericidal activity of normal rabbit serum than was the same strain without a plasmid. when the plasmid r100 was transferred to several k-12 strains, the strains acquired resistance to serum bactericidal activity. | 1976 | 786896 |
| plasmid incompatibility and control of replication: copy mutants of the r-factor r1 in escherichia coli k-12. | plasmid incompatibility was studied in escherichia coli k-12. by double-antibiotic selection, clones were constructed that carried the two r-factors r1 and r100, both belonging to the compatibility group fii. after release of the selection pressure, each of the two plasmids was lost at the same rate (8% per generation). mutants of r-factor r1 showing an increased number of copies per chromosome (copy mutants) were tested for their incompatibility towards r-factor r100. the results indicate that ... | 1975 | 1102525 |
| transience of the donor state in an escherichia coli k12 strain carrying a repressed r factor. | de-repression of the plasmid r100 in escherichia coli is essentially a transient phenomenon resulting in the transfer of several r factors to different recipient cells from a single donor cell. | 1975 | 1102925 |
| genetic loci responsible for incompatibility on a co-integrate plasmid, r100-1. | an r plasmid, r100-1, was mapped previously (yoshikawa, 1974) by transduction from an integratively suppressed hfr strain to a recipient with a mutation in gene dnaa. by this method various types of transductants of plasmid r100-1 that exist autonomously or in the integrated state were obtained. seventy-one such transductants were used in the present study to map gene inc, which is responsible for incompatibility. the results obtained can be explained by either of the following: (i) r100-1 has o ... | 1975 | 1104570 |
| [incompatible gene (inc) of plasmid r100-1]. | | 1975 | 1240267 |
| synthesis and degradation of the mrna of the tn21 mer operon. | the mercury resistance locus encoded by tn21 on the monocopy incfii plasmid r100 (mertn21) consists of a metal-responsive activator/repressor, merr, which controls initiation of a polycistronic message that includes genes for the uptake (mertpc) and reduction (mera) of hg2+ and merd, which may also play a minor regulatory role. comparison of the relative abundance of the 5' and 3' ends of the mertpcad transcript revealed a strong transcriptional gradient in the operon, consistent with previous o ... | 1992 | 1317460 |
| the stable maintenance system pem of plasmid r100: degradation of pemi protein may allow pemk protein to inhibit cell growth. | we constructed plasmids carrying heat-inducible pemi and pemk genes, which were fused with the collagen-lacz sequence in frame. the pemk-collagen-lacz (pemk*) protein produced from the fusion gene upon heat induction inhibited the growth of cells and killed most of the cells in the absence of the pemi protein but did not do so in the presence of the pemi protein. this supports our previous assumption that the pemk protein inhibits cell division, leading to cell death, whereas the pemi protein su ... | 1992 | 1624414 |
| site- and strand-specific nicking in vitro at orit by the tray-trai endonuclease of plasmid r100. | we developed an in vitro system to reproduce a site- and strand-specific nicking at the orit region of plasmid r100. the nicking reaction was dependent on the purified tray protein and on the lysate, which was prepared from cells overproducing the trai protein. this supports the idea that the protein products of two genes, tray and trai, constitute an endonuclease that introduces a specific nick in vivo in the orit region of the conjugative plasmids related to r100. the products were the "comple ... | 1991 | 1645338 |
| [primary structure of two natural is1-flanking transposons tn9* and tn9' coding for stability to chloramphenicol]. | the dna nucleotide sequence from the central region of the composite transposons tn9* and tn9' at the junction with the right copy of is1 was determined. from the data obtained it follows that both transposons are members of the tn9 family, although they contain additional dna segments with regard to tn9 of the length about 320 and 290 b.p. respectively lying distal to the cat gene. it was proposed that all the transposons of the tn9 family have been formed as a result of is1-mediated deletions ... | 1991 | 1654520 |
| structural and functional similarities between the replication region of the yersinia virulence plasmid and the repfiia replicons. | we sequenced the minimum replication region of the virulence plasmid pyve439-80 from a serogroup o:9 yersinia enterocolitica. this sequence is 68% homologous on a 1,873-nucleotide stretch to the sequence of the repfiia replicon of the resistance plasmid r100. the sequence contains two open reading frames, repa and repb, encoding proteins of 33,478 and 9,568 daltons, respectively. the amino acid sequences of the two proteins are 77 and 55% identical, respectively, to proteins repa1 and repa2 of t ... | 1990 | 1694522 |
| effect of gene amplification on mercuric ion reduction activity of escherichia coli. | the mercury resistance (mer) operon of plasmid r100 was cloned onto various plasmid vectors to study the effect of mer gene amplification on the rate of hg2+ reduction by escherichia coli cells. the plasmids were maintained at copy numbers ranging from 3 to 140 copies per cell. the overall hg2+ reduction rate of intact cells increased only 2.4-fold for the 47-fold gene amplification. in contrast, the rate of the cytoplasmic reduction reaction, measured in permeabilized cells, increased linearly ... | 1991 | 1785930 |
| four types of is1 with differences in nucleotide sequence reside in the escherichia coli k-12 chromosome. | the escherichia coli k-12 chromosome contains six copies of insertion element is1 at loci is1a-is1f. we determined their nucleotide (nt) sequences and found that they were classified into four types. two copies of is1 which flank a chromosomal segment containing the argf gene (is1b and is1c) have identical nt sequences. another identical pair are is1a and is1e. comparison of their nt sequences with the is1 in plasmid r100 revealed seven nt mismatches for is1a (or is1e), two for is1b (or is1c), f ... | 1991 | 1849492 |
| plasmid co1ib contains an ssi signal close to the replication origin. | taking advantage of the plaque morphology method, we identified a single-strand initiation (ssi) signal in plasmid psm32, a mini-co1ib plasmid. this ssi signal was situated in the 350-nt haeiii segment of the 1.8-kb s7 fragment, and located nearly 400 nt downstream of the origin of dna replication. introduction of the ssi signal into a mutant of filamentous phage m13 lacking oric resulted in restoration of phage growth and rfi dna synthesis. interestingly, dna homology studies showed that the nu ... | 1991 | 1857752 |
| specific dna binding of the tram protein to the orit region of plasmid r100. | the product of the tram gene of plasmid r100 was purified as the tram-collagen-beta-galactosidase fusion protein (tram*) by using a beta-galactosidase-specific affinity column, and the tram portion of tram* (tram') was separated by collagenolysis. both the tram* and tram' proteins were found to bind specifically to a broad region preceding the tram gene. this region (designated sbm) was located within the nonconserved region in orit among conjugative plasmids related to r100. the region seems to ... | 1991 | 1917866 |
| mobilization of the genetically engineered plasmid phsv106 from escherichia coli hb101(phsv106) to enterobacter cloacae in drinking water. | we have used triparental matings to demonstrate transfer (mobilization) of the nonconjugative genetically engineered plasmid phsv106, which contains the thymidine kinase gene of herpes simplex virus cloned into pbr322, from escherichia coli hb101 to an environmental isolate of enterobacter cloacae in sterile drinking water. this is the first demonstration of a two-step mobilization of a genetically engineered plasmid in any type of fresh water, including drinking water. transfer was mediated by ... | 1991 | 2036007 |
| structural and functional characterization of tnpi, a recombinase locus in tn21 and related beta-lactamase transposons. | a novel discrete mobile dna element from tn21 from the plasmid r100.1 is described, and its mobilization function was confirmed experimentally. in addition, the element behaves as a recombinase-active locus (tnpi) which facilitates insertions of antibiotic resistance genes as modules or cassettes at defined hot spots or integration sites. a similar tnpi sequence was detected by dna hybridization in a series of beta-lactamase transposons and plasmids and localized on their physical maps. the gene ... | 1990 | 2163386 |
| nucleotide sequence of the promoter-distal region of the tra operon of plasmid r100, including trai (dna helicase i) and trad genes. | the nucleotide sequence of the promoter-distal region of the tra operon of r100 was determined. there are five open reading frames in the region between trat and fino, and their protein products were identified. nucleotide sequences of plasmid f corresponding to the junction regions among the open reading frames seen in r100 were also determined. comparison of these nucleotide sequences revealed strong homology in the regions containing trad, trai and an open reading frame (named orfd). the trad ... | 1990 | 2164585 |
| specific binding of the tray protein to orit and the promoter region for the tray gene of plasmid r100. | the tray gene product of plasmid r100 was purified as a hybrid protein, tray-collagen-beta-galactosidase. the hybrid protein as well as the tray' protein, which was obtained by collagenolysis of the hybrid protein, specifically binds to an at-rich 36-base pair sequence (here called sbya) within the region including the origin of transfer, orit. the orit region consists of highly conserved and nonconserved regions among r100-related plasmids, and sbya was located within the nonconserved region im ... | 1990 | 2180949 |
| integration host factor affects expression of two genes at the conjugal transfer origin of plasmid r100. | integration host factor (ihf) binds to two sites near the origin of transfer of the conjugative antibiotic resistance plasmid, r100. dnase i footprinting shows that one site is immediately adjacent to orit and the gene x promoter, and another is adjacent to the tram promoter. a third site, known only from retardation gels, is near the traj promoter. the relative promoter activities of genes x, traj and tram are reduced in hima mutants (ihf-), as measured by chloramphenicol-resistance assays. tra ... | 1990 | 2215210 |
| derepression of conjugal transfer of the antibiotic resistance plasmid r100 by antisense rna. | conjugal transfer of the normally repressed antibiotic resistance plasmid r100 was derepressed by fragments of r100 that carried the traj promoter and the traj leader but lacked the finp promoter. | 1989 | 2468651 |
| sense and antisense transcripts of tram, a conjugal transfer gene of the antibiotic resistance plasmid r100. | the region of the antibiotic resistance plasmid r100 that encodes the plasmid-specific transfer gene tram has two tandemly aligned promoters separated by 145 nucleotides. the principal transcripts are 705 and 562 nucleotides long. minor transcripts are 1550 and 1700 nucleotides long. the 705-base transcript appears to encode an 11 kd tram protein. the 562-base transcript does not encode a detectable protein. when subcloned on short fragments, the promoter for the 562-base transcript initiates ef ... | 1989 | 2474740 |
| effect of the pem system on stable maintenance of plasmid r100 in various escherichia coli hosts. | we cloned the pem segment of plasmid r100 containing the two genes pemi and pemk, which are responsible for stable maintenance of r100 in dividing cells, into phs1, a temperature-sensitive replication mutant of plasmid psc101. we then examined the effect of the pem system on the maintenance of the resultant pem+ plasmid pdom17 in various escherichia coli host strains upon inhibition of replication of the plasmid at a high temperature. we show that the pem+ plasmid was maintained stably in the ce ... | 1989 | 2651892 |
| mercury operon regulation by the merr gene of the organomercurial resistance system of plasmid pdu1358. | the structural basis for induction of the mercury resistance operon with inorganic mercury and with the organomercurial compound phenylmercuric acetate was addressed by dna sequencing analysis and by lac fusion transcription experiments regulated by merr in trans from broad-spectrum-resistance plasmid pdu1358 (hg2+ and phenylmercury responding). the lac fusion results were compared with those from a narrow-spectrum-resistance (hg2+ responding but not phenylmercuric responding) operon and the pdu ... | 1989 | 2666393 |
| nucleotide sequence of the thiobacillus ferrooxidans chromosomal gene encoding mercuric reductase. | the nucleotide sequence of the thiobacillus ferrooxidans chromosomal mercuric-reductase-encoding gene (mera) has been determined. the mera gene contains 1635 bp, and shares 78.2% and 76.6% sequence homology with the transposon, tn501, and plasmid r100 mera genes, respectively. from the sequence, a 545-amino acid (aa) polypeptide was deduced, and comparison with those of tn501 and r100 revealed 80.6% and 80.0% homology, respectively, at the aa sequence level. divergence among the three mera aa se ... | 1989 | 2691338 |
| genetic and physical characterization of trimethoprim resistance plasmids from shigella sonnei and shigella flexneri. | analysis of six shigella flexneri and four s. sonnei isolates with trimethoprim (tp) resistance from clinical cases in ontario has shown that, in all isolates, the tp resistance is mediated by gene(s) on conjugative, multiple antibiotic-resistance plasmids. the physical and genetic characterization of these plasmids revealed that there are three different tp resistance plasmids. one group, composed of all six s. flexneri plasmids, consists of plasmids which are about 70 megadaltons (mda) and inh ... | 1987 | 2825949 |
| two genes, pemk and pemi, responsible for stable maintenance of resistance plasmid r100. | plasmid r100 was found to have two genes, designated pemk and pemi, that were responsible for its stable inheritance during cell division. they are located near the region that is essential for autonomous replication. under conditions that inhibit replication of r100 derivatives, the plasmid containing these pem genes gave only a few segregants in viable cells and increased the number of nonviable cells in the population, suggesting that a product from the pem region stabilized the plasmid by ki ... | 1988 | 2832364 |
| identification and characterization of the products from the traj and tray genes of plasmid r100. | the nucleotide sequence of part of the tra region of r100 including traj and tray was determined, and the products of several tra genes were identified. the nucleotide sequence of traj, encoding a protein of 223 amino acids, showed poor homology with the corresponding segments of other plasmids related to r100, but the deduced amino acid sequences showed low but significant homology. the first four amino acids at the n-terminal region of the traj protein were not essential for positive regulatio ... | 1988 | 2836369 |
| nucleotide sequence of gene x of antibiotic resistance plasmid r100. | | 1988 | 2837741 |
| requirement of the escherichia coli dnaa gene function for integrative suppression of dnaa mutations by plasmid r 100-1. | the phenotype of escherichia coli dnaa missense and nonsense mutations was integratively suppressed by plasmid r100-1. the suppressed strains, however, could not survive when the dnaa function was totally inactivated. this was demonstrated by the inability of replacing the dnaa allele in the suppressed strain by a dnaa::tn10 insertion using phage p1-mediated transduction. when the intact dnaa+ allele was additionally supplied by a specialized transducing phage, lambda imm21 dnaa+, which integrat ... | 1988 | 2851703 |
| restriction pattern and polypeptide homology among plasmid-borne mercury resistance determinants. | the structural and functional properties of mercury resistance determinants cloned from a series of independently isolated conjugative plasmids were compared with those of the prototype hgr determinants from tn501 and plasmid r100 (containing tn21). restriction endonuclease mapping classified the hgr determinants into at least three different but related structural groups which are distantly related to those from tn501 and r100. these relationships were confirmed by the functional analysis of su ... | 1988 | 2853390 |
| pin32: a cointegrate plasmid with inchi2 and incfii components. | an enterobacter cloacae strain isolated from the faeces of a child with diarrhoea in indonesia contained a transferable 216 mda plasmid, pin32, exhibiting inchi2 phenotypic characters, including temperature sensitivity of transfer and the expression of h serotype pili at a repressed level. a derivative plasmid (pin32-1), which had lost the inchi2 phenotype, and contained only 60 mda of the original replicon, was obtained after mating at 37 degrees c. it was incfii, showed regions of homology wit ... | 1986 | 2877047 |
| fertility inhibition gene of plasmid r100. | the fin0 gene of r100 was isolated from the fin0+ transducing phage va lambda 57. the limits of the gene were determined by bal31 digestions and by analysis of deletion mutations derived from an internal restriction site. the dna sequence contained an open reading frame of 558 nucleotides that would encode a protein of 21,268 daltons. synthesis of such a protein was observed only when the fragment was cloned in front of the tac promoter. deletions entering the large open reading frame from eithe ... | 1987 | 2951652 |
| mercuric reductase structural genes from plasmid r100 and transposon tn501: functional domains of the enzyme. | the nucleotide sequence for the 2240 bp of plasmid r100 following the merc gene of the mercuric resistance operon has been determined and compared with the homologous sequence of transposon tn501. the sequences following merc and preceding the next structural gene mera are unrelated between r100 and tn501 and differ in length, with 72 bp in tn501 and 509 bp in r100. the r100 sequence has a potential open reading frame (orf) for a 140 amino acid polypeptide with a reasonable translational start s ... | 1985 | 2989109 |
| identification of the merr gene of r100 by using mer-lac gene and operon fusions. | transcriptional (operon) and translational (gene) fusions between the r100 merr gene and lacz were constructed in vitro in a pbr322 plasmid carrying the mer genes derived from plasmid r100. the translational fusions were oriented in the opposite direction to and divergently from the mertcad genes. this shows that the reading frame previously thought to be merr was incorrect. expression of the gene fusion was repressed in trans by a compatible plasmid carrying the r100 merr+ gene, as was a simila ... | 1985 | 2993235 |
| the nucleotide sequence of the mercuric resistance operons of plasmid r100 and transposon tn501: further evidence for mer genes which enhance the activity of the mercuric ion detoxification system. | the dna sequences of the mercuric resistance determinants of plasmid r100 and transposon tn501 distal to the gene (mera) coding for mercuric reductase have been determined. these 1.4 kilobase (kb) regions show 79% identity in their nucleotide sequence, and in both sequences two common potential coding sequences have been identified. in r100, the end of the homologous sequence is disrupted by an 11.2 kb segment of dna which encodes the sulfonamide and streptomycin resistance determinants of tn21. ... | 1986 | 3007931 |
| polypeptides specified by the mercuric resistance (mer) operon of plasmid r100. | overlapping deletion mutations were constructed in chimaeric plasmids carrying the mer operon of plasmid r100. polypeptides specified by the mutant plasmids in escherichia coli minicells correlated with the mer genes as follows: mert, 17- and 16-kda polypeptides; merp, 9.8- and 9.5-kda polypeptides; merc, a 14-kda polypeptide; mera, 65- and 62-kda polypeptides. the products of the merr and merd genes were not identified. the revised nomenclature of the mer genes is explained. | 1986 | 3015742 |
| dna replication of the resistance plasmid r100 and its control. | | 1986 | 3019092 |
| characterization of the gene products produced in minicells by psm1, a derivative of r100. | at least ten polypeptides larger than 6 kilodaltons (k) are produced in minicells from the miniplasmid psm1 in vivo. psm1 (5804 bp) is a small derivative of the drug resistance plasmid r100 (ca. 90 kb) and carries the r100 essential replication region as well as some non-essential functions. cloned restriction fragments of psm1 and plasmids with deletions within psm1 sequences were used to assign eight of the ten observed polypeptides to specific coding regions of psm1. two of these polypeptides ... | 1986 | 3025559 |
| cloning and dna sequence of the mercuric- and organomercurial-resistance determinants of plasmid pdu1358. | the broad-spectrum mercurial-resistance plasmid pdu1358 was analyzed by cloning the resistance determinants and preparing a physical and genetic map of a 45-kilobase (kb) region of the plasmid that contains two separate mercurial-resistance operons that mapped about 20 kb apart. one encoded narrow-spectrum mercurial resistance to hg2+ and a few organomercurials; the other specified broad-spectrum resistance to phenylmercury and additional organomercurials. each determinant governed mercurial tra ... | 1987 | 3033633 |
| base substitutions in transposable element is1 cause dna duplication of variable length at the target site for plasmid co-integration. | we demonstrate that base substitutions in the is1 sequence affect the length of the nucleotide sequence which is duplicated during is1-mediated co-integration. is1k, an is1 variant present in the escherichia coli chromosome, has seven base substitutions in its sequence as compared with that of is1r derived from the plasmid r100. all substitutions are located in the internal region of is1k. we have constructed plasmids containing is1r, is1k and hybrids between them: one contains four base substit ... | 1987 | 3038535 |
| unidirectional replication of plasmid r100. | we isolated a 284 base-pair bamhi fragment of plasmid r100 that supports initiation of replication of a plasmid regardless of the orientation of the fragment. analysis of the specific radioactivity of restriction fragments from 32p-labeled replication intermediates synthesized in vitro shows that replication of the plasmid carrying the 284 base-pair fragment is unidirectional. the direction of replication depends on the orientation of the fragment present in the plasmid. the 5' ends of the leadi ... | 1988 | 3065512 |
| integration host factor and conjugative transfer of the antibiotic resistance plasmid r100. | transfer of plasmid r100-1 was reduced 100-fold in the absence of integration host factor. | 1987 | 3305485 |
| transcript analysis of the plasmid r100 traj and finp genes. | single-stranded rna probes were used to study the regulation of plasmid transfer in the infectious antibiotic resistance plasmid r100. transcription of the positive transfer control gene traj of r100 appears to be initiated continuously. in the presence of fino, the traj transcript is 235 bases long, and in the absence of fino it is 1050. these sizes are strain specific. fino increases four-to tenfold the amount of the transcript from the finp gene that is detectable in cells containing r100, r1 ... | 1987 | 3323829 |
| cloning, mapping, and sequencing of plasmid r100 tram and finp genes. | the fertility control gene finp, the transfer gene tram, and the transfer origin, orit, of plasmid r100 were isolated on a single 1.2-kilobase ecorv fragment and were then subcloned as haeiii fragments. the sequence of the 754-base-pair finp-containing fragment is reported here. in addition to the finp gene, the sequence includes all but two bases of the r100 tram open reading frame and apparently all of the leader mrna sequence and amino end of the traj gene of r100. the sequence contains two o ... | 1986 | 3522549 |
| orit sequence of the antibiotic resistance plasmid r100. | we present the nucleotide sequence of the orit region from plasmid r100. comparison to other incf plasmids revealed homology around the proposed nick sites as well as conservation of inverted repeated sequences in the nonhomologous region. three areas showed strong homology (eight of nine nucleotides) to the consensus sequence for binding of integration host factor, suggesting a role for this dna-binding protein in nicking at orit. | 1987 | 3611030 |
| some mercurial resistance plasmids from different incompatibility groups specify merr regulatory functions that both repress and induce the mer operon of plasmid r100. | transcription of the mer genes of plasmid r100 is regulated by the product of the merr gene. the merr gene negatively regulates its own expression and also controls the transcription of the mertca operon both negatively (in the absence of inducer) and positively (in the presence of inducer). we used transcriptional mer-lac fusions of r100-1 in complementation tests to measure the ability of the merr products of different mercury-resistant transposons and plasmids to functionally interact with r1 ... | 1985 | 3886634 |
| transfer of plasmids pbr322 and pbr325 in wastewater from laboratory strains of escherichia coli to bacteria indigenous to the waste disposal system. | laboratory strains of escherichia coli containing plasmid pbr325 (or pbr322) were coincubated with a mobilizer strain of e. coli (containing the conjugative plasmid r100-1) and a recipient strain of bacteria. bacterial strains isolated from raw wastewater or a plasmid-free e. coli laboratory strain served as recipients. transfer of the pbr plasmid into the recipient strain occurred during a 25-h coincubation in either l broth or sterilized wastewater; transfer frequencies were several orders of ... | 1985 | 3890739 |
| characterization and properties of very large inversions of the e. coli chromosome along the origin-to-terminus axis. | suppression of a dnaa46 mutation by integration of plasmid r100.1 derivatives in the termination region of chromosome replication in e. coli results in medium dependence, the suppressed bacteria being sensitive to rich medium at 42 degrees c. derivatives of such bacteria have been selected for growth at 42 degrees c in rich medium and we have analyzed representatives of the most frequently observed type: bacteria displaying, once cured of the suppressor plasmid, both rich-medium sensitivity and ... | 1985 | 3911026 |
| inhibition of flac transfer by the fin+ i-like plasmid r62. | flac mutants have been isolated in escherichia coli k-12 which carry dominant mutations resulting in insensitivity to transfer inhibition by the fin(+) i-like plasmid r62. these mutants were still sensitive to transfer inhibition by the fin(+) f-like plasmid r100 and, conversely, flactrao(-) and trap(-) mutants, which are insensitive to r100 inhibition, were still sensitive to r62. the sites of action of the two inhibition systems are therefore different. furthermore, inhibition by r62, unlike r ... | 1974 | 4370730 |
| mercuric ion-resistance operons of plasmid r100 and transposon tn501: the beginning of the operon including the regulatory region and the first two structural genes. | the mercuric ion-resistance operons of plasmid r100 (originally from shigella) and transposon tn501 (originally from a plasmid isolated in pseudomonas) have been compared by dna sequence analysis. the sequences for the first 1340 base pairs of tn501 are given with the best alignment with the comparable 1319 base pairs of r100. the homology between the two sequences starts at base 58 after the end of the insertion sequence is-1 of r100. the sequences include the transcriptional regulatory region, ... | 1984 | 6091128 |
| physical and genetic map of the organomercury resistance (omr) and inorganic mercury resistance (hgr) loci of the incm plasmid r831b. | tn7 insertion mutagenesis has been used to facilitate the generation of a physical (restriction endonuclease) and genetic map of the incm plasmid, r831b. the only selectable phenotypes carried by this 90-kb conjugative plasmid are resistances to inorganic mercury [hg(ii)] and to organomercury compounds. mutants in the hgr locus of r831b complemented previously described mutants in the mer operon of the incfii plasmid r100, indicating functional homology of the locus in each of these different pl ... | 1984 | 6099319 |
| a cointegrate of the bacteriophage p1 genome and the conjugative r plasmid r100. | | 1980 | 6100897 |
| variant pili produced by mutants of the flac plasmid. | transfer-proficient flac mutants with reduced abilities to plate various f-specific phages were isolated, either by selection after mutagenesis, or as revertants of flac traa mutants. in many of the mutants pilus-related properties were altered, including physical adsorption of r17 phage, the number of pili per cell and the outgrowth/retraction equilibrium. complementation studies showed that the mutations were in traa, suggesting that specific alterations in the amino-acid sequence of the pilin ... | 1980 | 6106661 |
| expression of plasmids coding for colonization factor antigen ii (cfa/ii) and enterotoxin production in escherichia coli. | two plasmids transferred from enterotoxigenic escherichia coli (etec) of serotype o6. h16 and biotypes a and c coded for mannose-resistant haemagglutination (mrha) and production of heat-stable enterotoxin (st) and heat-labile enterotoxin (lt). both plasmids were nonautotransferring being mobilized most efficiently by the r plasmid r100-1. they were similar in their genetic properties being incompatible with each other and plasmids of the inc group fi. the wild-type strains produced the coloniza ... | 1983 | 6142082 |
| biochemical characterization of hgcl2-inducible polypeptides encoded by the mer operon of plasmid r100. | minicells carrying the subcloned mer operon from plasmid r100 were pulse-labeled with [35s]methionine, and the labeled polypeptides were analyzed at various subsequent times by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the hg(ii) reductase monomer encoded by plasmid r100 occurred as two proteins of 69 and 66 kilodaltons (kd). the minor 66-kd protein is a modified form of the 69-kd protein. this modification occurs in vivo. both of these mer proteins are found in the soluble frac ... | 1982 | 6212579 |
| the fino gene of antibiotic resistance plasmid r100. | lambda phages carrying the r100 fino gene have been isolated from an r100:: lambda cointegrate in which lambda was inserted into the r100 trad gene at kb coordinate 72.1. physical analyses of these phages place the fino gene within r100 sali fragment d, near kb coordinate 82.0. analysis of proteins synthesized by the phages did not identify the fino gene product, although a constitutive protein of m.w. 30,100 was encoded by r100 dna between kb coordinates 78.7 and 81.2. | 1983 | 6224070 |
| dissection of the r-determinant of the plasmid r100.1: the sequence at the extremities of tn21. | we have sequenced the extremities of the transposon tn21, isolated from the r-determinant of the multiple antibiotic resistance plasmid r100.1, and show that it is a member of the tn3 family of elements. | 1981 | 6275355 |
| cloning a promoter that puts the expression of tetracycline resistance under the control of the regulatory elements of the mer operon. | we have sub-cloned from the eco ri-h fragments of the incfii plasmid r100 a 260-bp ecori fragment, using the promoter-cloning vehicle, pbrh4, (the inc fii plasmid codes for the mer operon, and pbrh4 expresses tetracycline resistance only when the deleted tet promoter has been replaced by another sequence that can serve as a promotor). with the 260-bp fragment inserted, the derivative plasmid, pfb4, directs the expression of tetracycline resistance only if there is a second plasmid in the strain ... | 1981 | 6277740 |
| recombination between two is/s flanking the r-determinant of r100-1: involvement of dor and reca gene functions in salmonella typhimurium. | drug resistance genes of the r-determinant component of a composite r plasmid r100-1 were frequently lost in salmonella typhimurium. various deletion mutants were analyzed by restriction endonuclease cleavage, southern blotting, and hybridization techniques. the loss of the r-determinant was found to be the result of a reciprocal recombination between the two is/s flanking the r-determinant. this recombination depended upon both dor and reca gene functions. | 1982 | 6277859 |
| promoter-distal region of the tra operon of f-like sex factor r100 in escherichia coli k-12. | the distal region of the tra (transfer) operon of f-like plasmid r100 was investigated, using small plasmids derived from r100, primarily the plasmid psm6. the transposon tn5 (which confers kanamycin resistance) was inserted at different positions into psm6, and the transposition derivatives were tested for ability to complement defined tra mutants of the f sex factor. thus, the tra genes trah, g, t, and d were localized on the plasmid r100. a restriction map of psm6 was constructed, and the loc ... | 1982 | 6277874 |
| nucleotide sequence analysis of the complement resistance gene from plasmid r100. | the multiple antibiotic resistance plasmid r100 renders escherichia coli resistant to the bactericidal action of serum complement. we constructed a plasmid (pow3) consisting of a 1,900-base-pair-long restriction fragment from r100 joined to a 2,900-base-pair-long fragment of pbr322 carrying ampicillin resistance. e. coli strains carrying pow3 or r100 were up to 10,000-fold less sensitive to killing by serum complement than were plasmid-free bacteria or bacteria carrying pbr322. nucleotide sequen ... | 1982 | 6284713 |
| a mutant of the plasmid r100.1 capable of producing autonomous circular forms of its resistance determinant. | | 1982 | 6285398 |
| analysis of plasmid genome evolution based on nucleotide-sequence comparison of two related plasmids of escherichia coli. | plasmid rsc13, a small derivative of the plasmid r1, contains a region necessary for replication as well as a complete copy (4957 bp) of the ampicillin resistance transposon, tn3. we determined the nucleotide sequence of the replication region of rsc13 to be 2937 bp and then compared this region (designated the 2.9-kb region) to the analogous region of psm1, a small derivative of the plasmid r100 which has common ancestry with r1. rsc13 and psm1 were 96% homologous in this 2.9-kb region except f ... | 1982 | 6286411 |
| mercuric reductase enzyme from a mercury-volatilizing strain of thiobacillus ferrooxidans. | cell-free mercury volatilization activity (mercuric reductase) was obtained from a mercury-volatilizing thiobacillus ferrooxidans strain, and the properties of intact-cell and cell-free activities were compared with those determined by plasmid r100 in escherichia coli. intact cells of t. ferrooxidans volatilized mercury at ph 2.5, whereas cells of e. coli did not. cell-free enzyme preparations from both bacteria functioned best at or above neutral ph and not at all at ph 2.5. the t. ferrooxidans ... | 1982 | 6286594 |
| distribution of insertion element is1 in natural isolates of escherichia coli. | total dnas from twelve natural isolates of escherichia coli from animals and humans were examined by hybridization with a probe for is1. considerable variation in copy number was found. in the case of two strains isolated from the same individual, one strain contained no copies of is1 and the other, much greater than 30. evidence was also obtained for the existence of is1-like elements (iso-is1s) of greater than 15% sequence divergence relative to the is1 from antibiotic resistance plasmid r100. | 1983 | 6306398 |
| tn5 insertion mutations in the mercuric ion resistance genes derived from plasmid r100. | the mercuric resistance (mer) genes of plasmid r100 were cloned into plasmid pbr322. a series of transposon tn5 insertion mutations in the mer genes were isolated and mapped. the mutants were characterized phenotypically by their sensitivity to hg2+ and by binding and volatilization of 203hg2+. dominance and complementation tests were also performed. mutations affecting the previously described mer genes merr (regulation), mert (transport), and mera (reductase) were characterized. evidence was o ... | 1983 | 6307976 |
| phenotypic reversion of an is1-mediated deletion mutation: a combined role for point mutations and deletions in transposon evolution. | we have physically characterised a deletion mutant of the r plasmid r100 which has lost all of the antibiotic resistances, including chloramphenicol resistance (cmr), coded by its is1-flanked r-determinant. the deletion was mediated by one of the flanking is1 elements and terminates within the carboxyl terminus of the cmr gene. dna sequence analysis showed that the mutated gene would produce a protein 20 amino acids longer than the wild-type due to fusion with an open reading frame in the is ele ... | 1982 | 6329702 |
| dnab analog function associated with plasmid r100drd-1. | plasmid r100 and a number of its derivatives were able to suppress the temperature sensitivity of strains carrying different alleles of the dnab gene of escherichia coli k-12. r100drd-l and par132 were able to rescue a strain carrying the dnab266(am) mutation in the absence of any known amber suppressors. this was taken as evidence for the existence of an r100drd-l dnab analog function. the r100drd-l dnab analog was different from those of bacteriophages p1 and p7 in that it was able to support ... | 1983 | 6337995 |
| the repa2 gene of the plasmid r100.1 encodes a repressor of plasmid replication. | we have constructed two miniplasmids, derived from the resistance plasmid r100.1. in one of these plasmids 400 bp of r100.1 dna have been replaced by dna from the transposon tn1000 (gamma-delta). this substitution removes the amino-terminal end of the repa2 coding sequence of r100.1 and results in an increased copy number of the plasmid carrying the substitution. the copy number of the substituted plasmid is reduced to normal levels in the presence of r100.1. the repa2 gene thus encodes a trans- ... | 1983 | 6356188 |
| suppression of induction of sos functions in an escherichia coli tif-1 mutant by plasmid r100.1. | the tif-1 mutation in the reca gene of escherichia coli caused, at 40 degrees c, lethal cell filamentation, induction of the reca protein, mutagenesis, and, in lambda lysogens, prophage induction. the presence of plasmid r100.1 in tif-1 strains suppressed tif-mediated cell filamentation and killing, reca protein induction, and prophage induction in lysogens. it also reduced mutagenesis in a tif-1 sfia11(r100.1) strain. plasmids f'lac, p1, and pmb9, in contrast, had little or no effect on tif-med ... | 1980 | 6444942 |
| lambda transducing phages carrying plasmid r100 replication genes. | | 1981 | 6457768 |
| characterization of complement resistance in escherichia coli conferred by the antibiotic resistance plasmid r100. | we have examined the effect of the antibiotic resistance plasmid, r100, on the complement (c) mediated killing of escherichia coli k-12 strains. the viabilities, in dilute normal rabbit serum (nrs), of 5 such strains were compared with the viabilities of the same strains harboring r100. for 1 strain, j6-2, we also measured the effect of r100 on viability in normal human serum (nhs) and in guinea pig serum (gps); in nrs, nhs,and gps devoid of classical c pathway activity; and in nhs devoid of alt ... | 1980 | 6997381 |
| [examinations about the segregation of r-plasmids in e. coli and klebsiella pneumoniae during nutrient broth passages (author's transl)]. | plasmid rp1 (= carbrneorkanartetrarampr) or plasmid r100 (= tetrarstreptrsulfr) were transferred on 5 different strains of e. coli and on 3 strains of kl. pneumoniae. plasmid rk1 (= carbrtetrstreptrampr) was transferred on 3 strains of kl. pneumoniae also. the resulting strains were cultured in 7 passages of standard-i-nutrient-broth (merck) and mueller-hinton-broth (becton-dickinson); 48 colonies were examined for resistance to antibiotics of the different r-plasmids. in e. coli and in kl. pneu ... | 1980 | 6999787 |
| production of extrachromosomal r-determinant circles from integrated r100.1: involvement of the e. coli recombination system. | the drug resistance plasmid r100.1 can integrate into the e. coli chromosome at several sites on the plasmid. many of the resulting hfr strains continuously produce extrachromosomal circular forms of the r-determinant. these r-det 'plasmids' seem incapable of stable autonomous replication. we show that their presence in the cell requires the continuous activity of functional reca and recc genes but does not require the lexa function. the production of r-det circular forms is correlated with an i ... | 1980 | 7003302 |
| suppression of escherichia coli dnaa46 mutations by integration of plasmid r100.1. derivatives: constraints imposed by the replication terminus. | we have studies the phenotypic suppression of a dnaa46 mutation by plasmid integration at preselected chromosomal sites after introducing homologous sequences (mu prophages) onto both the chromosomes and the suppressive plasmid. the plasmids used were all derived from plasmid r100.1. we found that the conditions required to get viable suppressive integration varied as the plasmid integration site moved from the origin to the terminus of chromosome replication. two constraints were observed. both ... | 1982 | 7047494 |
| characterization of the functional sites in the orit region involved in dna transfer promoted by sex factor plasmid r100. | we have previously identified three sites, named sbi, ihfa, and sbya, specifically recognized or bound by the trai, ihf, and tray proteins, respectively; these sites are involved in nicking at the origin of transfer, orit, of plasmid r100. in the region next to these sites, there exists the sbm region, which consists of four sites, sbma, sbmb, sbmc, and sbmd; this region is specifically bound by the tram protein, which is required for dna transfer. between sbmb and sbmc in this region, there exi ... | 1995 | 7635820 |
| large scale purification and characterization of trai endonuclease encoded by sex factor plasmid r100. | the trai protein encoded by plasmid r100 was purified in a large scale by monitoring the strand- and site-specific nicking activity at the origin of transfer, orit. the n-terminal amino acid sequence of the purified protein was identical to that deduced from the dna sequence of an open reading frame encoding trai. the trai protein is a dna helicase which is highly processive and unwinds dna in the 5' to 3' direction. the stokes radius and the sedimentation coefficient for the trai protein in 200 ... | 1995 | 7673168 |
| site- and strand-specific nicking at orit of plasmid r100 in a purified system: enhancement of the nicking activity of trai (helicase i) with tray and ihf. | we developed a purified system for reproducing the nicking reaction at the site 59 base pairs upstream of the tray protein binding site, sbya, in the orit region of plasmid r100. nicking at orit occurred efficiently in the presence of the plasmid-encoded proteins, trai and tray, integration host factor (ihf), and mg2+, but inefficiently in the presence of the trai protein and mg2+. the products were complex dna molecules with a protein covalently linked with the 5' end of the nick in the strand, ... | 1994 | 7883759 |
| mapping and disruption of the chpb locus in escherichia coli. | the chpb locus is a chromosomal homolog of the pem locus, which is responsible for stable maintenance of plasmid r100 within the host cells. like pem, chpb codes for two genes, chpbk and chpbi, encoding a growth inhibitor and a suppressor for the killing action of the chpbk protein, respectively. here, we determined the precise location of the chpb locus, which is linked to iler and ppa in the order iler-chpb-ppa, at 95.7 min on the map of escherichia coli. we then constructed mutants with an in ... | 1994 | 8083180 |
| comparative analysis of functional and structural features in the primase-dependent priming signals, g sites, from phages and plasmids. | the primase-dependent priming signals, g sites, are directly recognized by the escherichia coli primase (dnag gene product) and conduct the synthesis of primer rnas. in nucleotide sequence and secondary structure, there is no striking resemblance between the phage- and plasmid-derived g sites, except for the limited sequence homology near the start position of primer rna synthesis. in this study, we analyzed the structure and function of a g site of plasmid r100, g site (r100), and discovered th ... | 1994 | 8206839 |
| chpa and chpb, escherichia coli chromosomal homologs of the pem locus responsible for stable maintenance of plasmid r100. | the pem locus is responsible for stable maintenance of plasmid r100 and consists of two genes, pemi and pemk. the pemk gene product is a growth inhibitor, while the pemi gene product is a suppressor of this inhibitory function. we found that the pemi amino acid sequence is homologous to two open reading frames from escherichia coli called maze and orf-83, which are located at 60 and 100 min on the chromosome, respectively. we cloned and sequenced these loci and found additional open reading fram ... | 1993 | 8226627 |
| repression of the tram gene of plasmid r100 by its own product and integration host factor at one of the two promoters. | plasmid r100 codes for the tram gene, which is required for dna transfer and whose product has been shown to bind to the four sites, called sbma to sbmd, upstream of tram. to determine whether the tram protein regulates the expression of tram, we constructed the plasmids carrying various portions of the region upstream of the initiation codon atg for tram, which was fused with lacz in frame, and introduced them into the cells, which did or did not harbor another compatible plasmid carrying tram. ... | 1993 | 8331074 |
| autoregulation by cooperative binding of the pemi and pemk proteins to the promoter region of the pem operon. | the low copy number plasmid r100 carries the pem region, consisting of two genes, pemi and pemk, which are required for stable maintenance of the plasmid. here, to understand the regulation of the expression of the pem region, we constructed plasmids carrying either the pemi or the pemk gene, whose initiation codons were fused in frame with the lacz gene, and examined their expression by assaying beta-galactosidase (lacz) activity. the synthesis of both pemi and pemk proteins was found to be rep ... | 1993 | 8455570 |
| isolation of temperature-sensitive aminoacyl-trna synthetase mutants from an escherichia coli strain harboring the pemk plasmid. | the pem locus, which is responsible for the stable maintenance of the low copy number plasmid r100, contains the pemk gene, whose product has been shown to be a growth inhibitor. here, we attempted to isolate mutants which became tolerant to transient induction of the pemk protein. we obtained 20 mutants (here called pkt for pemk tolerance), of which 9 were temperature sensitive for growth. we analyzed the nine mutants genetically and found that they could be classified into three complementatio ... | 1993 | 8479423 |
| [killer genes from the leader region of conjugated plasmid r100 (incfii)]. | | 1996 | 8754005 |
| a new member of the hha/ymoa class of bacterial regulators in plasmid r100 of escherichia coli? | | 1996 | 8825785 |
| an m. tuberculosis dna fragment contains genes encoding cell division proteins ftsx and ftse, a basic protein and homologues of pemk and small protein b. | a 4-kb fragment of the m. tuberculosis chromosome was identified which contains several genes including those involved in cell division and possibly macrophage survival. dna sequence analysis revealed open reading frames (orfs) encoding putative proteins bearing significant homology with proteins ftsx and ftse associated with cell division in e. coli, with pemk protein which inhibits cell division in e. coli harboring plasmid r100 and with smpb protein of salmonella typhimurium implicated in its ... | 1996 | 8921846 |
| the finm promoter and the tram promoter are the principal promoters of the tram gene of the antibiotic resistance plasmid r100. | finp multicopy repression and traj multicopy derepression indicate that the ratio of sense to antisense transcripts is important in the regulation of r100 conjugation. the extension of r100 tram transcripts into traj shows that promoters in tram can affect this ratio, making the regulation of tram transcription important in the regulation of r100 conjugation. since r100 tram, tray and tral proteins bind to the tram promoter region, we examined tram transcription in r100-1 tram, tray and tral mut ... | 1997 | 9402017 |