Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| the rsma- mutants of erwinia carotovora subsp. carotovora strain ecc71 overexpress hrpnecc and elicit a hypersensitive reaction-like response in tobacco leaves. | erwinia carotovora subsp. carotovora wild-type strain ecc71 does not elicit the hypersensitive reaction (hr) in tobacco leaves. by mini-tn5-km and chemical mutagenesis we have isolated rsma- mutants of ecc71 that produce high basal levels of pectate lyases, polygalacturonase, cellulase, and protease; they also are hypervirulent. the rsma- mutants, but not their parent strains, elicit an hr-like response in tobacco leaves. this reaction is characterized by the rapid appearance of water soaking fo ... | 1996 | 8810071 |
| characterization of pectin methylesterase b, an outer membrane lipoprotein of erwinia chrysanthemi 3937. | the secretion of extracellular pectinases, among which there are least six isoenzymes of pectate lyase and one pectin methylesterase, allows the phytopathogenic bacterium erwinia chrysanthemi to degrade pectin. a gene coding for a novel pectin methylesterase has been cloned from an e. chrysanthemi strain 3937 gene library. this gene, pemb, codes for a 433-amino-acid protein. the pemb n-terminal region has the characteristics of lipoprotein signal sequences. we have shown that the pemb precursor ... | 1996 | 8830237 |
| complementation of deletion mutations in a cloned functional cluster of erwinia chrysanthemi out genes with erwinia carotovora out homologues reveals outc and outd as candidate gatekeepers of species-specific secretion of proteins via the type ii pathway. | the type ii or sec-dependent secretion system is used by diverse gram-negative bacteria for secretion of extracellular proteins. of the 12-15 proteins involved in secretion, the requirement for many has not been demonstrated and little is known about their functions in the secretion process. the plant pathogens erwinia chrysanthemi and erwinia carotovora secrete extra-cellular pectate lyases (pels) using the type ii or out pathway. however, these two bacteria cannot secrete pels encoded by heter ... | 1996 | 8861215 |
| global regulation in erwinia species by erwinia carotovora rsma, a homologue of escherichia coli csra: repression of secondary metabolites, pathogenicity and hypersensitive reaction. | our previous studies revealed that rsma of erwinia carotovora subsp. carotovora strain 71 suppressed the synthesis of the cell density (quorum) sensing signal n-(3-oxohexanoyl)-l-homoserine lactone, the production of extracellular enzymes and tissue macerating ability in soft-rotting erwinia species and that homologues of this negative regulator gene were present in other erwinia species. northern blot data presented here demonstrate that rsma and rsma-like genes are also expressed in soft-rotti ... | 1996 | 8932714 |
| analysis of bacterial carbapenem antibiotic production genes reveals a novel beta-lactam biosynthesis pathway. | carbapenems are beta-lactam antibiotics which have an increasing utility in chemotherapy, particularly for nosocomial, multidrug-resistant infections. strain gs101 of the bacterial phytopathogen, erwinia carotovora, makes the simple beta-lactam antibiotic, 1-carbapen-2-em-3-carboxylic acid. we have mapped and sequenced the erwinia genes encoding carbapenem production and have cloned these genes into escherichia coli where we have reconstituted, for the first time, functional expression of the be ... | 1996 | 8939426 |
| regulation of pelz, a gene of the pelb-pelc cluster encoding a new pectate lyase of erwinia chrysanthemi 3937. | the phytopathogenic enterobacterium erwinia chrysanthemi 3937 produces five major and several secondary endo-pectate lyases encoded by the pel genes. most of these genes are arranged in clusters on the bacterial chromosome. the genomic region surrounding the pelb-pelc cluster was supposed to be involved in the regulation of pelb and pelc synthesis. we demonstrated that the variation of pelb expression resulted from the titration of a regulatory protein by the gene adjacent to pelc. this gene was ... | 1996 | 8955401 |
| reca relieves negative autoregulation of rdga, which specifies a component of the reca-rdg regulatory circuit controlling pectin lyase production in erwinia carotovora ssp. carotovora. | the production of pectin lyase (pnl) in erwinia carotovora ssp. carotovora strain 71 is induced by dna-damaging agents such as mitomycin c (mc). this induction requires functions of reca, rdga and rdgb genes. based upon sequence homology, rdga was predicted to encode a repressor and rdgb was presumed to specify a transcriptional activator. to elucidate the function of rdga, the gene has been over-expressed in escherichia coli, and the 30 kda product purified by ammonium-sulphate precipitation, h ... | 1996 | 8971712 |
| genetic organization of a dna-processing region required for mobilization of a non-self-transmissible plasmid, pec3, isolated from erwinia carotovora subsp. carotovora. | a non-self-transmissible multiple-copy plasmid, pec3, isolated from the phytopathogenic bacterium, erwinia carotovora subsp. carotovora, can be mobilized by an incp-type plasmid. the hybrid plasmid vector, petc3, constructed from pec3 by fusion to markers conferring tcr and cmr, was transferred by conjugation from escherichia coli (ec) to various genera of enterobacteriaceae and to other genera of gram(-) bacteria which included xanthomonas, agrobacterium and rhizobium. deletion analysis and suc ... | 1996 | 8621089 |
| expression of an erwinia pectate lyase in three species of aspergillus. | transgenic filamentous fungi of the species aspergillus niger, a. nidulans and a. awamori expressing and secreting erwinia carotovora subsp. atroseptica pectate lyase 3 (pl3) were generated. correct processing of the pre-enzyme was achieved using the a. niger pectin lyase a (pel a) signal peptide. with the prepro-peptide of a. niger polygalacturonase ii, secreted enzymes still possessed the 6- aa pro-sequence, indicating the importance of the conformation of the precursor protein for correct cle ... | 1996 | 8625428 |
| characterization of engf, a gene for a non-cellulosomal clostridium cellulovorans endoglucanase. | a new clostridium cellulovorans (strain atcc 35296) endoglucanase gene engf has been isolated and sequenced. the gene contains 1671 bp and codes for a protein containing 557 amino acids and a mass of 60.1 kda. a putative signal peptide of 29 amino acids is present and the mature protein has a mass of 57.1 kda. engf does not have amino acid sequence homology to previously isolated engb and engd, but does show sequence homology to family 5 glycosyl hydrolases from bacillus, erwinia carotovora, and ... | 1996 | 8982083 |
| immunomagnetic separation of erwinia carotovora subsp. atroseptica from potato peel extracts to improve detection sensitivity on a crystal violet pectate medium or by pcr. | immunomagnetic separation (ims) procedures for the selective separation of erwinia carotovora subsp. atroseptica from potato peel extract were optimized for the recovery of target and removal of non-target bacteria. a streptomycin-resistant strain of erw. carotovora subsp. atroseptica was used in combination with a crystal violet pectate (cvp) medium supplemented with 100 micrograms ml-1 of streptomycin to determine the recovery level of the target bacterium. recovery obtained with a polyclonal ... | 1996 | 9072520 |
| bacteriocin small of rhizobium leguminosarum belongs to the class of n-acyl-l-homoserine lactone molecules, known as autoinducers and as quorum sensing co-transcription factors. | small bacteriocin was isolated from the culture broth of the gram-negative bacterium rhizobium leguminosarum, which forms symbiotic nitrogen-fixing root nodules on a number of leguminous plants. the structure of the molecule was elucidated by spectroscopic methods and identified as n-(3r-hydroxy-7-cis-tetradecanoyl)-l-homoserine lactone. the absolute configuration of both asymmetric carbon atoms in the molecule was determined by the use of the chiral solvating agents s-(+)- and r-(-)-2,2,2-trifl ... | 1996 | 8550454 |
| transplanting two unique beta-glucanase catalytic activities into one multienzyme, which forms glucose. | endo cellulases of plant pathogenic erwinias degrade cellulose as well as the cellulosic domains of barley (1-3,1-4)-beta-glucan. depolymerization of the latter substrate is mainly caused by (1-3,1-4)-beta-glucanases, which hydrolyze (1-4)-beta glycosidic linkages adjacent to (1-3)-beta linkages. to construct an enzyme for efficient degradation of barley (1-3,1-4)-beta-glucan, the sequence encoding the catalytic domain and interdomain linker of the cellulase from erwinia carotovora subspecies at ... | 1996 | 9636315 |
| analysis of bacterial carbapenem antibiotic production genes reveals a novel β-lactam biosynthesis pathway. | carbapenems are β-lactam antibiotics which have an increasing utility in chemotherapy, particularly for nosocomial, multidrug-resistant infections. strain gs101 of the bacterial phytopathogen, erwinia carotovora, makes the simple β-lactam antibiotic, 1-carbapen-2-em-3-carboxylic acid. we have mapped and sequenced the erwinia genes encoding carbapenem production and have cloned these genes into escherichia coli where we have reconstituted, for the first time, functional expression of the β-lactam ... | 1996 | 28777504 |
| ecbi and ecbr: homologs of luxi and luxr affecting antibiotic and exoenzyme production by erwinia carotovora subsp. betavasculorum. | erwinia carotovora subsp. betavasculorum ecb168 causes vascular necrosis and root rot of sugar beet and produces an antibiotic(s) that is antagonistic against other erwinia spp. ecbi- mutants of ecb168, each containing a single transposon insertion in the ecbi gene (for erwinia carotovora subsp. betavasculorum inducer), do not produce detectable levels of extracellular protease or antibiotic(s), and express less pectate lyase activity and virulence than the wild-type strain. a plasmid containing ... | 1997 | 9476353 |
| isolation and identification of antimicrobial furocoumarins from parsley. | photoactive furocoumarins extracted from four varieties of fresh and freeze-dried parsley leaves inhibited a dna repair-deficient escherichia coli in a photobiological assay. using media-modified assays, the human pathogens e. coli o157:h7 and listeria monocytogenes, the spoilage microorganism erwinia carotovora, and listeria innocua were also inhibited. pseudomonas fragi was not inhibited. minimum concentrations of forest green parsley powder in agar which showed inhibition ranged from 0.12% to ... | 1997 | 10465045 |
| elucidation of the structure of the core region and the complete structure of the r-type lipopolysaccharide of erwinia carotovora ferm p-7576. | an r-type lipopolysaccharide (lps) from erwinia carotovora strain ferm p-7576 was studied after strong alkaline degradation and mild acid hydrolysis. the resulting products were analyzed by fast-atom bombardment mass spectrometry, one- and two-dimensional 1h and 13c nmr spectroscopy, dephosphorylation and methylation analysis. the following structure was proposed for the core region of the lps: [formula in text] where hep is l-glycero-d-manno-heptose and kdo is 3-deoxy-d-manno-octulosonic acid. ... | 1997 | 9431990 |
| characterization of erwinia carotovora subsp. carotovora ly34 endo-1,4-beta-glucanase genes and rapid identification of their gene products. | genomic dna of the phytopathogenic erwinia carotovora subsp. carotovora ly34 was partially digested with sau3ai, ligated into the bamhi site of pblue-script ii sk+, and introduced into e. coli. two clones that were able to hydrolyse carboxymethylcellulose were selected. 1.5 kb and 1.2 kb fragments containing the cela and celb genes, respectively, were subcloned and sequenced. the cela and celb genes had open reading frames of 1,161 bp and 792 bp encoding 487 and 264 amino acid residues with calc ... | 1997 | 9434760 |
| salicylic acid interferes with tobacco mosaic virus replication via a novel salicylhydroxamic acid-sensitive mechanism. | salicylic acid (sa) induces resistance to all plant pathogens, including bacteria, fungi, and viruses, but the mechanism by which sa engenders resistance to viruses is not known. pretreatment of tobacco mosaic virus (tmv)-susceptible (nn genotype) tobacco tissue with sa reduced the levels of viral rnas and viral coat protein accumulating after inoculation with tmv. viral rnas were not affected equally, suggesting that sa treatment interferes with tmv replication. salicylhydroxamic acid (sham), a ... | 1997 | 12237364 |
| activation of the erwinia carotovora subsp. carotovora pectin lyase structural gene pnla: a role for rdgb. | the activation of pectin lyase (pnl) production in erwinia carotovora subsp. carotovora strain 71 occurs upon dna damage via a unique regulatory circuit involving reca, rdga and rdgb. in a similar pnl-inducible system reconstituted in escherichia coli, the rdgb product was found to activate the expression of pnla, the structural gene for pectin lyase. the kinetic data presented here also show that transcription of pnla followed that of rdgb in er. carotovora subsp. carotovora, indicating a tempo ... | 1997 | 9084157 |
| the general secretion pathway of erwinia carotovora subsp. carotovora: analysis of the membrane topology of outc and outf. | the out gene cluster of erwinia carotovora subsp. carotovora (ecc) encodes the proteins of the type ii or general secretory pathway (gsp) apparatus which is required for secretion of pectinase and cellulase. in this study, fusions between ecc out genes and the topology probe blam were constructed. the ability of out protein domains to export blam across the cytoplasmic membrane in both escherichia coli and the cognate host was utilized to confirm the computer-predicted cytoplasmic membrane topol ... | 1997 | 9084158 |
| identification of a pathogenicity locus, rpfa, in erwinia carotovora subsp. carotovora subsp. carotovora that encodes a two-component sensor-regulator protein. | a mutant of erwinia carotovora subsp. carotovora, ah2552, created by a mud1 insertion was found to be reduced in plant pathogenicity and deficient in extracellular protease and cellulase activity, although it produced normal levels of pectate lyase and polygalacturonase. a cosmid clone, pec462, was isolated from a wild-type e. carotovora subsp. carotovora dna library that concomitantly restored pathogenicity and protease and cellulase activities of ah2552 to wild-type levels when present in tran ... | 1997 | 9100385 |
| molecular characterization and expression of the erwinia carotovora hrpnecc gene, which encodes an elicitor of the hypersensitive reaction. | the nucleotide sequence of hrpnecc dna, cloned from erwinia carotovora subsp. carotovora strain ecc71, reveals a coding region of 1,068 bp which matches the size of hrpnecc transcripts. hrpnecc is predicted to encode a glycine-rich protein of approximately 36 kda. like the elicitors of the hypersensitive reaction (hr) produced by e. chrysanthemi (harpinech) and e. amylovora (harpinea), the deduced 36-kda protein does not possess a typical signal sequence, but it contains a putative membrane-span ... | 1997 | 9150595 |
| pegaspargase: an alternative? | to review the chemistry, pharmacology, pharmacokinetics, clinical activity, adverse effects, dosage, and administration guidelines for pegaspargase. | 1997 | 9161659 |
| characterization of acquired resistance in lesion-mimic transgenic potato expressing bacterio-opsin. | the lesion-mimic mutants of certain plants display necrotic lesions resembling those of the hypersensitive response and activate local and systemic defense responses in the absence of pathogens. we have engineered a lesion-mimic phenotype in transgenic russet burbank potato plants through constitutive expression of a bacterio-opsin (bo) proton pump derived from halobacterium halobium. transgenic potato plants exhibiting a lesion-mimic phenotype had increased levels of salicylic acid and overexpr ... | 1997 | 9204568 |
| the rna molecule csrb binds to the global regulatory protein csra and antagonizes its activity in escherichia coli. | the rna-binding protein csra (carbon storage regulator) is a new kind of global regulator, which facilitates specific mrna decay. a recombinant csra protein containing a metal-binding affinity tag (csra-h6) was purified to homogeneity and authenticated by n-terminal sequencing, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and other studies. this protein was entirely contained within a globular complex of approximately 18 csra-h6 subunits and a single approximatel ... | 1997 | 9211896 |
| polysialylated asparaginase: preparation, activity and pharmacokinetics. | erwinia carotovora l-asparaginase was coupled covalently to colominic acid, a low molecular mass polysialic acid, by reductive amination. depending on the molar ratios of colominic acid-asparaginase (50:1, 100:1 and 250:1), polysialylated constructs contained 4.2-8.1 molecules of colominic acid per molecule of enzyme. such constructs retained most (82-86%) of the initial asparaginase activity and also maintained the km values of the native enzyme towards the substrate asparagine. on exposure to ... | 1997 | 9300806 |
| mobilization, cloning, and sequence determination of a plasmid-encoded polygalacturonase from a phytopathogenic burkholderia (pseudomonas) cepacia. | phytopathogenic strains of burkholderia cepacia (synonym pseudomonas cepacia) produce endopolygalacturonase, whereas strains of clinical and soil origin do not. growth of a phytopathogenic strain (atcc25416) at elevated temperatures resulted in nonpectolytic derivatives that were either cured of a resident plasmid or contained a plasmid of reduced mass. the resident 200-kb plasmid (ppec320) in strain atcc25416 was tagged with tn5-mob. the ppec320::tn5-mob (ppec321) plasmid was mobilized in b. ce ... | 1997 | 9304858 |
| avirulence gene d of pseudomonas syringae pv. tomato may have undergone horizontal gene transfer. | avirulence gene d (avrd) is carried on the b-plasmid of the plant pathogen pseudomonas syringae pv. tomato with plasmid-borne avrd homologs widely distributed among the pseudomonads. we now report sequences in the soft rot pathogen erwinia carotovora that cross-hybridize to avrd suggesting a conserved function beyond avirulence. alternatively, avrd may have been transferred horizontally among species: (i) dna linked to avrd shows evidence of class ii transpositions and contains a novel is3-relat ... | 1997 | 9326365 |
| phylogenetic analysis of erwinia species based on 16s rrna gene sequences. | the phylogenetic relationships of the type strains of 16 erwinia species were investigated by performing a comparative analysis of the sequences of the 16s rrna genes of these organisms. the sequence data were analyzed by the neighbor-joining method, and each branch was supported by moderate bootstrap values. the phylogenetic tree and sequence analyses confirmed that the genus erwinia is composed of species that exhibit considerable heterogeneity and form four clades that are intermixed with mem ... | 1997 | 9336906 |
| control of virulence gene expression by plant calcium in the phytopathogen erwinia carotovora. | plant calcium can modulate a particular plant-pathogen interaction and have a decisive role in disease development. enhanced resistance to the phytopathogenic enterobacterium erwinia carotovora, the causal agent of bacterial soft rot disease, is observed in high-calcium plants. one of the main virulence determinants of e. carotovora, the peha endopolygalacturonase, is specifically required in the early stages of the infection. production of peha was found to be dependent on the calcium concentra ... | 1997 | 9364909 |
| both dna gyrase and reverse gyrase are present in the hyperthermophilic bacterium thermotoga maritima. | like all hyperthermophiles yet tested, the bacterium thermotoga maritima contains a reverse gyrase. here we show that it contains also a dna gyrase. the genes top2a and top2b encoding the two subunits of a dna gyrase-like enzyme have been cloned and sequenced. the top2a (type ii dna topoisomerase a protein) is more similar to gyra (dna gyrase a protein) than to parc [topoisomerase iv (topo iv) c protein]. the difference is especially striking at the c-terminal domain, which differentiates dna gy ... | 1997 | 9380682 |
| pectate lyase peli of erwinia chrysanthemi 3937 belongs to a new family. | erwinia chrysanthemi 3937 secretes five major isoenzymes of pectate lyases encoded by the pel4, pelb, pelc, peld, and pele genes and a set of secondary pectate lyases, two of which, pell and pelz, have been already identified. we cloned the peli gene, encoding a ninth pectate lyase of e. chrysanthemi 3937. the peli reading frame is 1,035 bases long, corresponding to a protein of 344 amino acids including a typical amino-terminal signal sequence of 19 amino acids. the purified mature peli protein ... | 1997 | 9393696 |
| the rap and hor proteins of erwinia, serratia and yersinia: a novel subgroup in a growing superfamily of proteins regulating diverse physiological processes in bacterial pathogens. | the enteric bacterium serratia marcescens is an opportunistic human pathogen. the strain atcc39006 makes the red pigment, prodigiosin (pig), and the beta-lactam antibiotic carbapenem (car). mutants were isolated that were concomitantly defective for pig and car production. these mutants were found to have a mutation in the rap gene (regulation of antibiotic and pigment). sequence analysis of the rap gene revealed a predicted protein product showing strong homology to slya, originally thought to ... | 1997 | 9402023 |
| analysis of the carbapenem gene cluster of erwinia carotovora: definition of the antibiotic biosynthetic genes and evidence for a novel beta-lactam resistance mechanism. | members of two genera of gram-negative bacteria, serratia and erwinia, produce a beta-lactam antibiotic, 1-carbapen-2-em-3-carboxylic acid. we have reported previously the cloning and sequencing of the genes responsible for production of this carbapenem in erwinia carotovora. these genes are organized as an operon, cara--h, and are controlled by a luxr-type transcriptional activator, encoded by the linked carr gene. we report in this paper the genetic dissection of this putative operon to determ ... | 1997 | 9402024 |
| isolation and characterization of new c-terminal substitution mutations affecting secretion of polygalacturonase in erwinia carotovora ssp. carotovora. | an intact c-terminus was previously shown to be required for stability and secretion of the polygalacturonase (peha) in erwinia carotovora ssp. carotovora. here we have analyzed the effects of amino acid (aa) substitutions generated to five c-terminal positions of peha. conservation of two hydrophobic and one non-hydrophobic residue (v372, v374 and n371, respectively) was found to be essential for maintenance of the protein stability. as an exception, one of the mutants (v372g) did not show majo ... | 1997 | 9000526 |
| characterization of the agrobacterium vitis peha gene and comparison of the encoded polygalacturonase with the homologous enzymes from erwinia carotovora and ralstonia solanacearum. | dna sequencing of the agrobacterium vitis peha gene revealed a predicted protein with an m(r) of 58,000 and significant similarity to the polygalacturonases of two other plant pathogens, erwinia carotovora and ralstonia (= pseudomonas or burkholderia) solanacearum. sequencing of the n terminus of the peha protein demonstrated cleavage of a 34-amino-acid signal peptide from pre-peha. mature peha accumulated primarily in the periplasm of a. vitis and peha+ escherichia coli cells during exponential ... | 1997 | 8979363 |
| phylogenetical relationship based on groe genes among phenotypically related enterobacter, pantoea, klebsiella, serratia and erwinia species. | in an attempt to define the phylogenetical relationship among 17 phenotypically related species of genera enterobacter, pantoea, serratia, klebsiella and erwinia, we determined almost all of their groe operon sequences using the polymerase chain reaction direct sequencing method. the number of nucleotide substitutions per site was 0.12+/-0.030. the value was 3.6-fold higher than that of 16s rdna. as a result, we were successful in constructing molecular phylogenetic trees which had a finer resol ... | 1997 | 12501307 |
| drosophila host defense: differential induction of antimicrobial peptide genes after infection by various classes of microorganisms. | insects respond to microbial infection by the rapid and transient expression of several genes encoding potent antimicrobial peptides. herein we demonstrate that this antimicrobial response of drosophila is not aspecific but can discriminate between various classes of microorganisms. we first observe that the genes encoding antibacterial and antifungal peptides are differentially expressed after injection of distinct microorganisms. more strikingly, drosophila that are naturally infected by entom ... | 1997 | 9405661 |
| use of subtractive hybridization to design habitat-based oligonucleotide probes for investigation of natural bacterial communities. | we describe a rapid oligonucleotide probe design strategy based on subtractive hybridization which yields probes for 16s rrna or rrna genes of individual members of microbial communities that are specific within the context of those communities. this strategy circumvents the need to sequence many similar or identical clones of dominant members of a community. radioactively labeled subfragments of a cloned 16s rrna gene sequence for which a probe is required (target) were hybridized with biotinyl ... | 1998 | 9435075 |
| molecular and biotechnological aspects of microbial proteases. | proteases represent the class of enzymes which occupy a pivotal position with respect to their physiological roles as well as their commercial applications. they perform both degradative and synthetic functions. since they are physiologically necessary for living organisms, proteases occur ubiquitously in a wide diversity of sources such as plants, animals, and microorganisms. microbes are an attractive source of proteases owing to the limited space required for their cultivation and their ready ... | 1998 | 9729602 |
| analysis of biolog gn substrate utilization patterns by microbial communities. | biolog gn plates are increasingly used to characterize microbial communities by determining the ability of the communities to oxidize various carbon sources. studies were done to determine whether the biolog gn plate assay accurately reflects the catabolic potential of the inoculum used. to gain insight into which populations of microbial communities contribute to the biolog patterns, denaturing gradient gel electrophoresis and temperature gradient gel electrophoresis (tgge) were used to assess ... | 1998 | 16349535 |
| the pseudomonas aeruginosa quorum-sensing signal molecule n-(3-oxododecanoyl)-l-homoserine lactone has immunomodulatory activity. | diverse gram-negative bacterial cells communicate with each other by using diffusible n-acyl homoserine lactone (ahl) signal molecules to coordinate gene expression with cell population density. accumulation of ahls above a threshold concentration renders the population "quorate," and the appropriate target gene is activated. in pathogenic bacteria, such as pseudomonas aeruginosa, ahl-mediated quorum sensing is involved in the regulation of multiple virulence determinants. we therefore sought to ... | 1998 | 9423836 |
| complementation analysis of the dichelobacter nodosus fimn, fimo, and fimp genes in pseudomonas aeruginosa and transcriptional analysis of the fimnop gene region. | the causative agent of ovine footrot, the gram-negative anaerobe dichelobacter nodosus, produces polar type iv fimbriae, which are the major protective antigens. the d. nodosus genes fimn, fimo, and fimp are homologs of the pseudomonas aeruginosa fimbrial assembly genes, pilb, pilc, and pild, respectively. both the pild and fimp genes encode prepilin peptidases that are responsible for cleavage of the leader sequence from the immature fimbrial subunit. to investigate the functional similarity of ... | 1998 | 9423871 |
| cloning and nucleotide sequence of the dna gyrase gyra gene from serratia marcescens and characterization of mutations in gyra of quinolone-resistant clinical isolates. | the sequence of the dna gyrase gyra gene of serratia marcescens atcc 14756 was determined. an open reading frame of 2,640 nucleotides coding for a polypeptide with a calculated molecular mass of 97,460 was found, and its sequence complemented the sequence of an escherichia coli gyra temperature-sensitive mutation. analysis of the pcr products of the quinolone resistance-determining regions of gyra genes from six quinolone-resistant clinical isolates revealed a single amino acid substitution, ser ... | 1998 | 9449286 |
| intracellular immunization of prokaryotic cells against a bacteriotoxin. | intracellularly expressed antibodies have been designed to bind and inactivate target molecules inside eukaryotic cells. here we report that an antibody fragment can be used to probe the periplasmic localization of the colicin a n-terminal domain. colicins form voltage-gated ion channels in the inner membrane of escherichia coli. to reach their target, they bind to a receptor located on the outer membrane and then are translocated through the envelope. the n-terminal domain of colicins is involv ... | 1998 | 9457852 |
| molecular characterization and heterologous expression of the gene encoding a low-molecular-mass endoglucanase from trichoderma reesei qm9414. | we have isolated the genomic and cdna clones encoding eg iii (a low-molecular-mass endo-beta-1,4-glucanase) gene from trichoderma reesei qm9414. the nucleotide sequence of the cdna fragment was verified to contain a 702-bp open reading frame that encodes a 234-amino-acid propeptide. the deduced protein sequence has significant homologies with family h endo-beta-1,4-glucanases. the 16-amino-acid n-terminal sequence was shown to function as a leader peptide for possible secretion. northern blot an ... | 1998 | 9464393 |
| a pheromone-independent carr protein controls carbapenem antibiotic synthesis in the opportunistic human pathogen serratia marcescens. | strain atcc 39006 of serratia marcescens makes the same carbapenem, (5r)-carbapen-2-em-3-carboxylic acid (car), as the erwinia carotovora strain gs101. unlike e. carotovora, where the onset of production occurs in the late-exponential phase of growth in response to the accumulation of the small diffusible pheromone n-(3-oxohexanoyl)-l-homoserine lactone (ohhl), in s. marcescens carbapenem is produced throughout the growth phase and does not appear to involve any diffusible pheromone molecule. tw ... | 1998 | 9467912 |
| role of rpos in stress survival and virulence of vibrio cholerae. | vibrio cholerae is known to persist in aquatic environments under nutrient-limiting conditions. to analyze the possible involvement of the alternative sigma factor encoded by rpos, which is shown to be important for survival during nutrient deprivation in several other bacterial species, a v. cholerae rpos homolog was cloned by functional complementation of an escherichia coli mutant by using a wild-type genomic library. sequence analysis of the complementing clone revealed an 1.008-bp open read ... | 1998 | 9473029 |
| luxi- and luxr-homologous genes of rhizobium etli cnpaf512 contribute to synthesis of autoinducer molecules and nodulation of phaseolus vulgaris. | autoinduction plays an important role in intercellular communication among symbiotic and pathogenic gram-negative bacteria. we report here that a nitrogen-fixing symbiont of phaseolus vulgaris, rhizobium etli cnpaf512, produces at least seven different autoinducer molecules. one of them exhibits a growth-inhibitory effect like that of the bacteriocin small [n-(3r-hydroxy-7-cis-tetradecanoyl)-l-homoserine lactone]. at least two of the other autoinducers are synthesized by a luxi-homologous autoin ... | 1998 | 9473034 |
| 4-coumarate:coenzyme a ligase in hybrid poplar. properties of native enzymes, cdna cloning, and analysis of recombinant enzymes. | the enzyme 4-coumarate:coenzyme a ligase (4cl) is important in providing activated thioester substrates for phenylpropanoid natural product biosynthesis. we tested different hybrid poplar (populus trichocarpa x populus deltoides) tissues for the presence of 4cl isoforms by fast-protein liquid chromatography and detected a minimum of three 4cl isoforms. these isoforms shared similar hydroxycinnamic acid substrate-utilization profiles and were all inactive against sinapic acid, but instability of ... | 1998 | 9489021 |
| salmonella typhimurium encodes an sdia homolog, a putative quorum sensor of the luxr family, that regulates genes on the virulence plasmid. | quorum sensing is a phenomenon in which bacteria sense and respond to their own population density by releasing and sensing pheromones. in gram-negative bacteria, quorum sensing is often performed by the luxr family of transcriptional regulators, which affect phenotypes as diverse as conjugation, bioluminescence, and virulence gene expression. the gene encoding one luxr family member, named sdia (suppressor of cell division inhibition), is present in the escherichia coli genome. in this report, ... | 1998 | 9495757 |
| the rpos gene of erwinia carotovora: gene organization and functional expression in e. coli. | rpos homologues were identified in several erwinia species using escherichia coli rpos sequences as probes. the rpos gene from erwinia carotovora was cloned and the deduced amino acid sequence had 91% identity to e. coli rpos. the latter sigma factor regulates the stationary phase inducible hpii catalase activity of e. coli. in an e. coli rpos mutant, the e. carotovora rpos gene was also able to regulate synthesis of this catalase. the presence of a similar catalase in e. carotovora suggests tha ... | 1998 | 9503622 |
| external loops at the c terminus of erwinia chrysanthemi pectate lyase c are required for species-specific secretion through the out type ii pathway. | the type ii secretion system (main terminal branch of the general secretion pathway) is used by diverse gram-negative bacteria to secrete extracellular proteins. proteins secreted by this pathway are synthesized with an n-terminal signal peptide which is removed upon translocation across the inner membrane, but the signals which target the mature proteins for secretion across the outer membrane are unknown. the plant pathogens erwinia chrysanthemi and erwinia carotovora secrete several isozymes ... | 1998 | 9515910 |
| differential patterns of acquired virulence genes distinguish salmonella strains. | analysis of several salmonella typhimurium in vivo-induced genes located in regions of atypical base composition has uncovered acquired genetic elements that cumulatively engender pathogenicity. many of these regions are associated with mobile elements, encode predicted adhesin and invasin-like functions, and are required for full virulence. some of these regions distinguish broad host range from host-adapted salmonella serovars and may contribute to inherent differences in host specificity, tis ... | 1998 | 9539791 |
| development of pcr assays for species- and type-specific identification of pasteurella multocida isolates. | genomic subtractive hybridization of closely related pasteurella multocida isolates has generated clones useful in distinguishing hemorrhagic septicemia-causing type b strains from other p. multocida serotypes. oligonucleotide primers designed during the sequencing of these clones have proved valuable in the development of pcr assays for rapid species- and type-specific detection of p. multocida and of type b:2 in particular. this study demonstrated that the primer pair designed from the sequenc ... | 1998 | 9542944 |
| nuclease overexpression mutants of serratia marcescens. | a family of mutants overexpressing the serratia marcescens extracellular nuclease has been known for decades. a number of these alleles are characterized here at the molecular level, and the mutant genes are identified, yielding a likely model for their phenotype. the known mutations exert their effect indirectly on nuca expression by elevating the basal sos response of the cell. mutations have been found in xerc and uvrd, both of which result in partial sos induction. a classic nucsu allele, th ... | 1998 | 9555916 |
| cloning and sequencing of the cela gene encoding cmcase of erwinia carotovora subsp. carotovora ly34. | the phytopathogenic erwinia carotovora subsp. carotovora ly34 secretes multiple isozymes of the plant cell wall-disintegrating enzyme, endoglucanases. genomic dna from ecc ly34 was digested with sau3ai and ligated into the bamhi site of pbluescript ii sk+. one of the e. coli clones containing a sau3ai fragment of ecc genomic dna hydrolyzed carboxymethyl cellulose and was shown to contain the 2.2 kb bamhi restriction fragment, which was subcloned to generate plyca100 named as cela. the structural ... | 1998 | 9571628 |
| antibiotic production by erwinia herbicola eh1087: its role in inhibition of erwinia amylovora and partial characterization of antibiotic biosynthesis genes. | mutants of erwinia herbicola eh1087 (ant-), which did not produce antibiotic activity against erwinia amylovora, the fire blight pathogen, were selected after tnphoa mutagenesis. in immature pear fruit ant- mutants grew at the same rate as wild-type strain eh1087 but did not suppress development of the disease caused by e. amylovora. these results indicated that antibiosis plays an important role in the suppression of disease by strain eh1087. all of the ant- mutations obtained were located in a ... | 1998 | 9572960 |
| endopolygalacturonase pg1 in different formae speciales of fusarium oxysporum | pg1, the major endopolygalacturonase of the vascular wilt pathogen fusarium oxysporum, was secreted during growth on pectin by 10 of 12 isolates belonging to seven formae speciales, as determined with isoelectric focusing zymograms and sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. a southern analysis of genomic dna and pcr performed with gene-specific primers revealed that the pg1 locus was highly conserved structurally in most isolates. two pg1-deficient isolates were identifi ... | 1998 | 9572983 |
| pseudomonas aeruginosa lasr transcription correlates with the transcription of lasa, lasb, and toxa in chronic lung infections associated with cystic fibrosis. | the role of pseudomonas aeruginosa quorum-sensing systems in the lung infections associated with cystic fibrosis (cf) has not been examined. the purpose of this study was to determine if genes regulated by the lasr-lasi quorum-sensing system were coordinately regulated by the p. aeruginosa populations during the lung infections associated with cf. we also wanted to ascertain if there was a relationship between the expression of lasr, a transcriptional regulator, and some p. aeruginosa virulence ... | 1998 | 9596711 |
| isolation, characterization, molecular gene cloning, and sequencing of a novel phytase from bacillus subtilis. | the bacillus subtilis strain vtt e-68013 was chosen for purification and characterization of its excreted phytase. purified enzyme had maximal phytase activity at ph 7 and 55 degrees c. isolated enzyme required calcium for its activity and/or stability and was readily inhibited by edta. the enzyme proved to be highly specific since, of the substrates tested, only phytate, adp, and atp were hydrolyzed (100, 75, and 50% of the relative activity, respectively). the phytase gene (phyc) was cloned fr ... | 1998 | 9603817 |
| multidomain structure and cellulosomal localization of the clostridium thermocellum cellobiohydrolase cbha. | the nucleotide sequence of the clostridium thermocellum f7 cbha gene, coding for the cellobiohydrolase cbha, has been determined. an open reading frame encoding a protein of 1,230 amino acids was identified. removal of a putative signal peptide yields a mature protein of 1,203 amino acids with a molecular weight of 135,139. sequence analysis of cbha reveals a multidomain structure of unusual complexity consisting of an n-terminal cellulose binding domain (cbd) homologous to cbd family iv, an imm ... | 1998 | 9620957 |
| an autonomously replicating transforming vector for sulfolobus solfataricus. | a plasmid able to transform and to be stably maintained both in sulfolobus solfataricus and in escherichia coli was constructed by insertion into an e. coli plasmid of the autonomously replicating sequence of the virus particle ssv1 and a suitable mutant of the hph (hygromycin phosphotransferase) gene as the transformation marker. the vector suffered no rearrangement and/or chromosome integration, and its copy number in sulfolobus was increased by exposure of the cells to mitomycin c. | 1998 | 9620978 |
| a negative regulator mediates quorum-sensing control of exopolysaccharide production in pantoea stewartii subsp. stewartii. | classical quorum-sensing (autoinduction) regulation, as exemplified by the lux system of vibrio fischeri, requires n-acyl homoserine lactone (ahl) signals to stimulate cognate transcriptional activators for the cell density-dependent expression of specific target gene systems. for pantoea stewartii subsp. stewartii, a bacterial pathogen of sweet corn and maize, the extracellular polysaccharide (eps) stewartan is a major virulence factor, and its production is controlled by quorum sensing in a po ... | 1998 | 9636211 |
| unsaturated oligogalacturonic acids are generated by in vitro treatment of pectin with human faecal flora. | pectins with a degree of esterification (de) of 95, 66, 34 and 0%, respectively, were incubated in vitro with human faecal flora (ph 7.8). the concentration and composition of oligogalacturonic acids (oligogala) generated were determined using high-performance thin-layer chromatography (hptlc) with uv and colorimetric detection. in the first period of the anaerobic degradation, the pectin macromolecules were fragmented into unsaturated oligogala as intermediate products by the action of bacteria ... | 1998 | 10335591 |
| cryptic carbapenem antibiotic production genes are widespread in erwinia carotovora: facile trans activation by the carr transcriptional regulator. | few strains of erwinia carotovora subsp. carotovora (ecc) make carbapenem antibiotics. strain gs101 makes the basic carbapenem molecule, 1-carbapen-2-em-3-carboxylic acid (car). the production of this antibiotic has been shown to be cell density dependent, requiring the accumulation of the small diffusible molecule n-(3-oxohexanoyl)-l-homoserine lactone (ohhl) in the growth medium. when the concentration of this inducer rises above a threshold level, ohhl is proposed to interact with the transcr ... | 1998 | 9639920 |
| the hexa gene of erwinia carotovora encodes a lysr homologue and regulates motility and the expression of multiple virulence determinants. | we have identified a gene important for the regulation of exoenzyme virulence factor synthesis in the plant pathogen erwinia carotovora ssp. carotovora (ecc) and virulence and motility in erwinia carotovora ssp. atroseptica (eca). this gene, hexa (hyperproduction of exoenzymes), is a close relative of the erwinia chrysanthemi (echr) gene pect and encodes a member of the lysr family of transcriptional regulators. hexa mutants in both ecc and eca produce abnormally high levels of the exoenzyme vir ... | 1998 | 9643539 |
| effect of insertion site and metabolic load on the environmental fitness of a genetically modified pseudomonas fluorescens isolate. | an isolate of pseudomonas fluorescens (sbw25) was modified with different marker genes (laczy, aph-1, and xyle). these marker genes were inserted singly or in combination into two separate (1 mbp apart) and presumably nonessential sites (-6- and ee) on the chromosome of sbw25. this allowed the production of a range of genetically modified sbw25 variants that differed with respect to insertion site of the marker genes and metabolic burden. the environmental fitness of the different sbw25 variants ... | 1998 | 9647841 |
| rpos (sigma-s) controls expression of rsma, a global regulator of secondary metabolites, harpin, and extracellular proteins in erwinia carotovora. | rpos (sigma-s or sigma-38) controls a large array of genes that are expressed during stationary phase and under various stress conditions in escherichia coli and other bacteria. we document here that plant pathogenic and epiphytic erwinia species, such as e. amylovora; e. carotovora subsp. atroseptica, betavasculorum, and carotovora; e. chrysanthemi; e. herbicola; e. rhapontici; and e. stewartii, possess rpos genes and produce the alternate sigma factor. we show that rpos transcription in e. car ... | 1998 | 9658007 |
| cloning and characterization of a cmcase gene, celb, of erwinia carotovora subsp. carotovora ly34 and its comparison to cela. | the phytopathogenic erwinia carotovora subsp. carotovora (ecc) ly34 secretes multiple isozymes of the plant cell wall-disintegrating enzyme endoglucanase. we isolated a second cel gene encoding cmcase in ecc ly34. a 3.7 kb fragment was subcloned to generate plycb100 (celb). the structural organization of the celb gene consists of an open reading frame (orf) of 792 bp encoding 264 264 amino acid residues with a calculated molecular weight of 29,890 da the predicted amino acid sequence of celb is ... | 1998 | 9666464 |
| two-component regulators involved in the global control of virulence in erwinia carotovora subsp. carotovora. | production of extracellular, plant cell wall degrading enzymes, the main virulence determinants of the plant pathogen erwinia carotovora subsp. carotovora, is coordinately controlled by a complex regulatory network. insertion mutants in the exp (extracellular enzyme production) loci exhibit pleiotropic defects in virulence and the growth-phase-dependent transcriptional activation of genes encoding extracellular enzymes. two new exp mutations, designated expa and exps, were characterized. introdu ... | 1998 | 9675890 |
| evidence against the double-arginine motif as the only determinant for protein translocation by a novel sec-independent pathway in escherichia coli. | proteins which are synthesized with a signal peptide containing a 'double-arginine' motif may be translocated across the bacterial cytoplasmic membrane by a mechanism that is different from the known sec and signal recognition particle pathways. the function of the double-arginine motif as a determinant for this novel pathway was studied by expressions of gene constructs coding for the high potential iron-sulfur protein (hipip) from chromatium vinosum d in escherichia coli. when the protein was ... | 1998 | 9682482 |
| premature polyadenylation at multiple sites within a bacillus thuringiensis toxin gene-coding region. | some foreign genes introduced into plants are poorly expressed, even when transcription is controlled by a strong promoter. perhaps the best examples of this problem are the cry genes of bacillus thuringiensis (b.t.), which encode the insecticidal proteins commonly referred to as b.t. toxins. as a step toward overcoming such problems most effectively, we sought to elucidate the mechanisms limiting the expression of a typical b.t.-toxin gene, cryia(c), which accumulates very little mrna in tobacc ... | 1998 | 9701599 |
| characterization of a novel rna regulator of erwinia carotovora ssp. carotovora that controls production of extracellular enzymes and secondary metabolites. | the enterobacterium erwinia carotovora ssp. carotovora strain 71 (hereafter ecc71) produces extracellular enzymes such as pectate lyase isozymes (pels), cellulase (cel), polygalacturonase (peh) and protease (prt). these enzymes degrade plant cell wall components and are largely responsible for the elicitation of soft-rot diseases in plants and plant products. ecc71 also produces harpinecc, the elicitor of hypersensitive reaction (hr) and the quorum-sensing signal, n-(3-oxohexanoyl)-l-homoserine ... | 1998 | 9701816 |
| development of rrna-targeted pcr and in situ hybridization with fluorescently labelled oligonucleotides for detection of yersinia species. | in this report, we present details of two rapid molecular detection techniques based on 16s and 23s rrna sequence data to identify and differentiate yersinia species from clinical and environmental sources. near-full-length 16s rrna gene (rdna) sequences for three different yersinia species and partial 23s rdna sequences for three y. pestis and three y. pseudotuberculosis strains were determined. while 16s rdna sequences of y. pestis and y. pseudotuberculosis were found to be identical, one base ... | 1998 | 9705392 |
| conditional mutations in oute and outl block exoenzyme secretion across the erwinia carotovora outer membrane. | the phytopathogen erwinia carotovora subspecies carotovora secretes pectinases and cellulase via the general secretory pathway, a process requiring at least 13 proteins encoded by the out gene cluster. by exploiting delta::tn5, a generalised transducing phage (psi kp) and localised mutagenesis of the out gene cluster, we have produced a histidine auxotroph and 19 new secretory mutants, including two (hjn1003 and hjn1004) which were conditional (temperature sensitive) for secretion. all of the mu ... | 1998 | 9711844 |
| chitinolytic activity in chromobacterium violaceum: substrate analysis and regulation by quorum sensing. | quorum sensing control mediated by n-acyl homoserine lactone (ahl) signaling molecules has been established as a key feature of the regulation of exoenzyme production in many gram-negative bacteria. in chromobacterium violaceum atcc 31532 a number of phenotypic characteristics, including production of the purple pigment violacein, hydrogen cyanide, antibiotics, and exoproteases are known to be regulated by the endogenous ahl n-hexanoyl-l-homoserine lactone (hhl). in this study we show that c. vi ... | 1998 | 9721280 |
| cloning and identification of conjugative transfer origins in the rhizobium meliloti genome. | a simple approach was used to identify rhizobium meliloti dna regions with the ability to convert a nontransmissible vector into a mobilizable plasmid, i.e., to contain origins of conjugative transfer (orit, mob). reca-defective r. meliloti merodiploid populations, where each individual contained a hybrid cosmid from an r. meliloti gr4 gene library, were used as donors en masse in conjugation with another r. meliloti recipient strain, selecting transconjugants for vector-encoded antibiotic resis ... | 1998 | 9721299 |
| crystal structure of polygalacturonase from erwinia carotovora ssp. carotovora. | the crystal structure of the 40-kda endo-polygalacturonase from erwinia carotovora ssp. carotovora was solved by multiple isomorphous replacement and refined at 1.9 a to a conventional crystallographic r-factor of 0.198 and rfree of 0.239. this is the first structure of a polygalacturonase and comprises a 10 turn right-handed parallel beta-helix domain with two loop regions forming a "tunnel like" substrate-binding cleft. sequence conservation indicates that the active site of polygalacturonase ... | 1998 | 9733763 |
| characterization of pucd5000 involved in pink disease color formation by pantoea citrea. | pantoea citrea, the causal agent of pink disease of pineapple, harbors a cryptic plasmid of 5229 bp. designated pucd5000. on the basis of nucleotide and amino acid sequence analyses, pucd5000 contains both replication and mobilization loci (bom and mobcabd) that are similar to those in plasmids psw100 and psw200 in pantoea stewartii and pec3 in erwinia carotovora subsp. carotovora. the survival of p. citrea on pineapple does not depend on pucd5000. however, full pink coloration development, whic ... | 1998 | 9735319 |
| hrpw of erwinia amylovora, a new harpin that contains a domain homologous to pectate lyases of a distinct class. | harpins, such as hrpn of erwinia amylovora, are extracellular glycine-rich proteins that elicit the hypersensitive reaction (hr). we identified hrpw of e. amylovora, which encodes a protein similar to known harpins in that it is acidic, rich in glycine and serine, and lacks cysteine. a putative hrpl-dependent promoter was identified upstream of hrpw, and western blot analysis of hrpl mutants indicated that the production of hrpw is regulated by hrpl. hrpw is secreted via the hrp (type iii) pathw ... | 1998 | 9748455 |
| the pseudomonas syringae pv. tomato hrpw protein has domains similar to harpins and pectate lyases and can elicit the plant hypersensitive response and bind to pectate. | the host-specific plant pathogen pseudomonas syringae elicits the hypersensitive response (hr) in nonhost plants and secretes the hrpz harpin in culture via the hrp (type iii) secretion system. previous genetic evidence suggested the existence of another harpin gene in the p. syringae genome. hrpw was found in a region adjacent to the hrp cluster in p. syringae pv. tomato dc3000. hrpw encodes a 42. 9-kda protein with domains resembling harpins and pectate lyases (pels), respectively. hrpw has ke ... | 1998 | 9748456 |
| pcr-based detection of the causal agent of watermark disease in willows (salix spp.) | the watermark disease, caused by brenneria salicis (formerly erwinia salicis), is of significant concern wherever tree-forming willows are grown or occur naturally. the movement of infected, asymptomatic cuttings is a major cause of pathogen dispersal. a reliable and sensitive diagnostic procedure is necessary for the safe movement of willow planting material. we derived primers from the nucleotide sequence of the 16s rrna gene of b. salicis for the development of a pcr to detect this pathogen. ... | 1998 | 9758827 |
| analogs of the autoinducer 3-oxooctanoyl-homoserine lactone strongly inhibit activity of the trar protein of agrobacterium tumefaciens. | the trar and trai proteins of agrobacterium tumefaciens mediate cell-density-dependent expression of the ti plasmid tra regulon. trai synthesizes the autoinducer pheromone n-(3-oxooctanoyl)-l-homoserine lactone (3-oxo-c8-hsl), while trar is an 3-oxo-c8-hsl-responsive transcriptional activator. we have compared the abilities of 3-oxo-c8-hsl and 32 related compounds to activate expression of a trar-regulated promoter. in a strain that expresses wild-type levels of trar, only 3-oxo-c8-hsl was stron ... | 1998 | 9765571 |
| global regulation by the small rna-binding protein csra and the non-coding rna molecule csrb. | csr (carbon storage regulator) is a recently discovered global regulatory system that controls bacterial gene expression post-transcriptionally. its effector is a small rna-binding protein referred to as csra or, in phytopathogenic erwinia species, rsma (repressor of stationary phase metabolites). numerous genes whose expression occurs in the stationary phase of growth are repressed by csra/rsma, and csra activates certain exponential-phase metabolic pathways. glycogen synthesis and catabolism, ... | 1998 | 9781871 |
| characterization of the erwinia chrysanthemi expi-expr locus directing the synthesis of two n-acyl-homoserine lactone signal molecules. | the plant pathogen erwinia chrysanthemi produces three acyl-homoserine lactones (acyl-hsls). one has been identified as n-(3-oxohexanoyl)-homoserine lactone (ohhl), and the two others were supposed to be n (hexanoyl)-homoserine lactone (hhl) and n-(decanoyl)-homoserine lactone (dhl). the genes for a quorum-sensing signal generator (expi) and a response regulator (expr) were cloned. these genes are convergently transcribed and display high similarity to the expi-expr genes of erwinia carotovora. ... | 1998 | 9781877 |
| endochitinase is transported to the extracellular milieu by the eps-encoded general secretory pathway of vibrio cholerae. | the chia gene of vibrio cholerae encodes a polypeptide which degrades chitin, a homopolymer of n-acetylglucosamine (glcnac) found in cell walls of fungi and in the integuments of insects and crustaceans. chia has a coding capacity corresponding to a polypeptide of 846 amino acids having a predicted molecular mass of 88.7 kda. a 52-bp region with promoter activity was found immediately upstream of the chia open reading frame. insertional inactivation of the chromosomal copy of the gene confirmed ... | 1998 | 9791107 |
| detection of ralstonia solanacearum, which causes brown rot of potato, by fluorescent in situ hybridization with 23s rrna-targeted probes. | during the past few years, ralstonia (pseudomonas) solanacearum race 3, biovar 2, was repeatedly found in potatoes in western europe. to detect this bacterium in potato tissue samples, we developed a method based on fluorescent in situ hybridization (fish). the nearly complete genes encoding 23s rrna of five r. solanacearum strains and one ralstonia pickettii strain were pcr amplified, sequenced, and analyzed by sequence alignment. this resulted in the construction of an unrooted tree and suppor ... | 1998 | 9797321 |
| engineering of a single-chain variable-fragment (scfv) antibody specific for the stolbur phytoplasma (mollicute) and its expression in escherichia coli and tobacco plants | from a hybridoma cell line (2a10) producing an immunoglobulin g1 directed against the major membrane protein of the stolbur phytoplasma, we have engineered scfv (single-chain variable-fragment) antibodies from the variable heavy (vh) and light (vl) domains of the immunoglobulin. the scfv gene was cloned and expressed in escherichia coli. the expressed protein of 30 kda could be recovered from the periplasmic fraction of the bacterial cells and was shown to be fully functional toward its phytopla ... | 1998 | 9797323 |
| the oxyr gene from erwinia carotovora: cloning, sequence analysis and expression in escherichia coli. | homologs of the escherichia coli oxyr gene were identified in several erwinia species, using a combination of pcr and southern hybridization analysis. the oxyr gene from erwinia carotovora was isolated on a cosmid clone and characterized. the gene and deduced gene product shared high level sequence identity with their e. coli counterparts (78 and 89% identity, respectively). in e. coli, the oxyr gene is a transcriptional activator that, under oxidizing conditions, induces expression of a set of ... | 1998 | 9809430 |
| adherence of the gram-positive bacterium ruminococcus albus to cellulose and identification of a novel form of cellulose-binding protein which belongs to the pil family of proteins. | the adherence of ruminococcus albus 8 to crystalline cellulose was studied, and an affinity-based assay was also used to identify candidate cellulose-binding protein(s). bacterial adherence in cellulose-binding assays was significantly increased by the inclusion of either ruminal fluid or micromolar concentrations of both phenylacetic and phenylpropionic acids in the growth medium, and the addition of carboxymethylcellulose (cmc) to assays decreased the adherence of the bacterium to cellulose. a ... | 1998 | 9811650 |
| identification and characterization of the fis operon in enteric bacteria. | the small dna binding protein fis is involved in several different biological processes in escherichia coli. it has been shown to stimulate dna inversion reactions mediated by the hin family of recombinases, stimulate integration and excision of phage lambda genome, regulate the transcription of several different genes including those of stable rna operons, and regulate the initiation of dna replication at oric. fis has also been isolated from salmonella typhimurium, and the genomic sequence of ... | 1998 | 9811652 |
| the bacillus subtilis nucleotidyltransferase is a trna cca-adding enzyme. | there has been increased interest in bacterial polyadenylation with the recent demonstration that 3' poly(a) tails are involved in rna degradation. poly(a) polymerase i (pap i) of escherichia coli is a member of the nucleotidyltransferase (ntr) family that includes the functionally related trna cca-adding enzymes. thirty members of the ntr family were detected in a search of the current database of eubacterial genomic sequences. gram-negative organisms from the beta and gamma subdivisions of the ... | 1998 | 9829937 |
| mutational analysis of the rhizobium etli reca operator. | based upon our earlier studies (a. tapias, a. r. fernández de henestrosa, and j. barbé, j. bacteriol. 179:1573-1579, 1997) we hypothesized that the regulatory sequence of the rhizobium etli reca gene was ttgn11caa. however, further detailed analysis of the r. etli reca operator described in the present work suggests that it may in fact be gaacn7gtac. this new conclusion is based upon pcr mutagenesis analysis carried out in the r. etli reca operator, which indicates that the gaac and gtac submoti ... | 1998 | 9829943 |
| bacillus subtilis bs 107 as an antagonist of potato blackleg and soft rot bacteria. | antimicrobial substances were produced by bacillus subtilis bs 107 in a defined medium and isolated from culture filtrate by precipitation at ph 2.5. active fractions were extracted in ethyl acetate, acetone, and 80% ethanol and purified by thin-layer chromatography (tlc) on silica gel plates developed with an ethanol-water mixture (2:1, v/v). in each case, a band with a rf of 0.75 formed an inhibitory zone when the tlc plates were placed in contact with agar seeded with test cultures of the erw ... | 1998 | 9830107 |
| purification, characterization, and molecular analysis of thermostable cellulases cela and celb from thermotoga neapolitana. | two thermostable endocellulases, cela and celb, were purified from thermotoga neapolitana. cela (molecular mass, 29 kda; pi 4.6) is optimally active at ph 6.0 at 95 degreesc, while celb (molecular mass, 30 kda; pi 4.1) has a broader optimal ph range (ph 6.0 to 6.6) at 106 degreesc. both enzymes are characterized by a high level of activity (high vmax value and low apparent km value) with carboxymethyl cellulose; the specific activities of cela and celb are 1,219 and 1,536 u/mg, respectively. wit ... | 1998 | 9835561 |
| identification and characterization of the erwinia amylovora rpos gene: rpos is not involved in induction of fireblight disease symptoms. | the erwinia amylovora rpos gene, encoding the alternative sigma factor rpos, has been cloned and characterized. though highly sensitive to a number of environmental stresses, an e. amylovora rpos mutant was not compromised in its ability to grow or cause disease symptoms within apple seedlings or in an overwintering model. | 1998 | 9852034 |
| an endoglucanase, egla, from the hyperthermophilic archaeon pyrococcus furiosus hydrolyzes beta-1,4 bonds in mixed-linkage (1-->3),(1-->4)-beta-d-glucans and cellulose. | the egla gene, encoding a thermostable endoglucanase from the hyperthermophilic archaeon pyrococcus furiosus, was cloned and expressed in escherichia coli. the nucleotide sequence of the gene predicts a 319-amino-acid protein with a calculated molecular mass of 35.9 kda. the endoglucanase has a 19-amino-acid signal peptide but not cellulose-binding domain. the p. furiosus endoglucanase has significant amino acid sequence similarities, including the conserved catalytic nucleophile and proton dono ... | 1999 | 9864341 |
| thermal gradient gel electrophoresis analysis of bioprotection from pollutant shocks in the activated sludge microbial community. | we used a culture-independent approach, namely, thermal gradient gel electrophoresis (tgge) analysis of ribosomal sequences amplified directly from community dna, to determine changes in the structure of the microbial community following phenol shocks in the highly complex activated sludge ecosystem. parallel experimental model sewage plants were given shock loads of chlorinated and methylated phenols and simultaneously were inoculated (i) with a genetically engineered microorganism (gem) able t ... | 1999 | 9872766 |