Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| genetic and biochemical characterization of an exopolygalacturonase and a pectate lyase from yersinia enterocolitica. | yersinia enterocolitica, an invasive foodborne human pathogen, degrades polypectate by producing two depolymerizing enzymes, pectate lyase (pl) and polygalacturonase (pg). the gene encoding the pg activity, designated pehy, was located in a 3-kb genomic fragment of y. enterocolitica atcc 49397. the complete nucleotide sequence of this 3-kb fragment was determined and an open reading frame consisting of 1803 bp was predicted to encode a pg protein with an estimated m(r) of 66 kda and pi of 6.3. t ... | 1999 | 10446714 |
| engineering endoglucanase-secreting strains of ethanologenic klebsiella oxytoca p2. | recombinant klebsiella oxytoca p2 was developed as a biocatalyst for the simultaneous saccharification and fermentation (ssf) of cellulose by chromosomally integrating zymomonas mobilis genes (pdc, adhb) encoding the ethanol pathway. this strain contains the native ability to transport and metabolize cellobiose, eliminating the need to supplement with beta-glucosidase during ssf. to increase the utility of this biocatalyst, we have now chromosomally integrated the celz gene encoding the primary ... | 1999 | 10455486 |
| isolation of an extracellular protease gene of erwinia carotovora subsp. carotovora strain scc3193 by transposon mutagenesis and the role of protease in phytopathogenicity. | using mini-tn5cmr::gusa, a transposon that allows transcriptional fusions to a promoterless beta-glucuronidase gene, a mutant of erwinia carotovora subsp. carotovora scc3193 deficient in extracellular protease production and soft-rot pathogenicity in plants was isolated. the mutant, designated scc6004, produced normal levels of pectate lyase, polygalacturonase and cellulase. the region of the transposon insertion was partially sequenced to permit the design of specific oligonucleotide primers to ... | 1999 | 10463162 |
| a new class of cobalamin transport mutants (btuf) provides genetic evidence for a periplasmic binding protein in salmonella typhimurium. | no periplasmic binding protein has been demonstrated for the atp-binding cassette (abc)-type cobalamin transporter btucd. new mutations (btuf) are described that affect inner-membrane transport. the btuf protein has a signal sequence and resembles the periplasmic binding proteins of several other abc transporters. | 1999 | 10464235 |
| purification and characterization of an extracellular protease from the fish pathogen yersinia ruckeri and effect of culture conditions on production. | a novel protease, hydrolyzing azocasein, was identified, purified, and characterized from the culture supernatant of the fish pathogen yersinia ruckeri. exoprotease production was detected at the end of the exponential growth phase and was temperature dependent. activity was detected in peptone but not in casamino acid medium. its synthesis appeared to be under catabolite repression and ammonium control. the protease was purified in a simple two-step procedure involving ammonium sulfate precipit ... | 1999 | 10473403 |
| characterization of an acetyl xylan esterase from the anaerobic fungus orpinomyces sp. strain pc-2. | a 1,067-bp cdna, designated axea, coding for an acetyl xylan esterase (axea) was cloned from the anaerobic rumen fungus orpinomyces sp. strain pc-2. the gene had an open reading frame of 939 bp encoding a polypeptide of 313 amino acid residues with a calculated mass of 34,845 da. an active esterase using the original start codon of the cdna was synthesized in escherichia coli. two active forms of the esterase were purified from recombinant e. coli cultures. the size difference of 8 amino acids w ... | 1999 | 10473406 |
| development and application of pathovar-specific monoclonal antibodies that recognize the lipopolysaccharide o antigen and the type iv fimbriae of xanthomonas hyacinthi. | the objective of this study was to develop a specific immunological diagnostic assay for yellow disease in hyacinths, using monoclonal antibodies (mabs). mice were immunized with a crude cell wall preparation (shear fraction) from xanthomonas hyacinthi and with purified type iv fimbriae. hybridomas were screened for a positive reaction with x. hyacinthi cells or fimbriae and for a negative reaction with x. translucens pv. graminis or erwinia carotovora subsp. carotovora. nine mabs recognized fim ... | 1999 | 10473431 |
| fungal resistance to plant antibiotics as a mechanism of pathogenesis. | many plants produce low-molecular-weight compounds which inhibit the growth of phytopathogenic fungi in vitro. these compounds may be preformed inhibitors that are present constitutively in healthy plants (also known as phytoanticipins), or they may be synthesized in response to pathogen attack (phytoalexins). successful pathogens must be able to circumvent or overcome these antifungal defenses, and this review focuses on the significance of fungal resistance to plant antibiotics as a mechanism ... | 1999 | 10477313 |
| differential protease-mediated turnover of h-ns and stpa revealed by a mutation altering protein stability and stationary-phase survival of escherichia coli. | the escherichia coli proteins h-ns is recognized as an important component among the major nucleoid-associated proteins. in studies of e. coli strains with defects in h-ns, we discovered a mutant that phenotypically restored stationary-phase viability (rsv) of such strains. the rsv phenotype was the result of a mutation that led to severalfold higher levels of the functionally and structurally related stpa protein. this mutation was a base pair change in the stpa structural gene, and the amino a ... | 1999 | 10485902 |
| regulation of peld and pele, encoding major alkaline pectate lyases in erwinia chrysanthemi: involvement of the main transcriptional factors. | the main virulence factors of the phytopathogenic bacterium erwinia chrysanthemi are pectinases which attack pectin, the major constituent of the plant cell wall. of these enzymes, the alkaline isoenzyme named peld in strain 3937 and pele in strain ec16 has been described as being particularly important, based on virulence studies of plants. expression of the peld and pele genes is tightly modulated by various regulators, including the kdgr repressor and the cyclic amp-cyclic amp receptor protei ... | 1999 | 10498706 |
| rsmc of the soft-rotting bacterium erwinia carotovora subsp. carotovora negatively controls extracellular enzyme and harpin(ecc) production and virulence by modulating levels of regulatory rna (rsmb) and rna-binding protein (rsma). | previous studies have shown that the production of extracellular enzymes (pectate lyase [pel], polygalacturonase [peh], cellulase [cel], and protease [prt]) and harpin(ecc) (the elicitor of hypersensitive reaction) in erwinia carotovora subsp. carotovora is regulated by rsma, an rna-binding protein, and rsmb, a regulatory rna (rsm stands for regulator of secondary metabolites) (y. liu et al., mol. microbiol. 29:219-234, 1998). we have cloned and characterized a novel regulatory gene, rsmc, that ... | 1999 | 10498717 |
| mutational analysis of the recj exonuclease of escherichia coli: identification of phosphoesterase motifs. | the recj gene, identified in escherichia coli, encodes a mg(+2)-dependent 5'-to-3' exonuclease with high specificity for single-strand dna. genetic and biochemical experiments implicate recj exonuclease in homologous recombination, base excision, and methyl-directed mismatch repair. genes encoding proteins with strong similarities to recj have been found in every eubacterial genome sequenced to date, with the exception of mycoplasma and mycobacterium tuberculosis. multiple genes encoding protein ... | 1999 | 10498723 |
| the three asparaginases. comparative pharmacology and optimal use in childhood leukemia. | asparaginase (asp) is a standard component of the antileukemia armamentarium. there are currently 3 preparations of asparaginase available: (1) e. coli (asp, elspar); (2) the enzyme derived from erwinia chrysanthemi (erw, erwinase); (3) pegaspargase (peg, oncaspar), the e. coli enzyme modified by covalent attachment of polyethylene glycol. this report describes the findings of 3 pharmacologic end points: asp enzyme activity in patients' sera, depletion of asparagine and the development of anti-a ... | 1999 | 10500842 |
| opening the iron box: transcriptional metalloregulation by the fur protein. | 1999 | 10515908 | |
| ferric enterochelin transport in yersinia enterocolitica: molecular and evolutionary aspects. | yersinia enterocolitica is well equipped for siderophore piracy, encompassing the utilization of siderophores such as ferrioxamine, ferrichrome, and ferrienterochelin. in this study, we report on the molecular and functional characterization of the yersinia fep-fes gene cluster orthologous to the escherichia coli ferrienterochelin transport genes (fepa, fepdgc, and fepb) and the esterase gene fes. in vitro transcription-translation analysis identified polypeptides of 30 and 35 kda encoded by fep ... | 1999 | 10515929 |
| effectors of a developmental mitogen-activated protein kinase cascade revealed by expression signatures of signaling mutants. | despite the importance of mitogen-activated protein kinase (mapk) signaling in eukaryotic biology, the mechanisms by which signaling yields phenotypic changes are poorly understood. we have combined transcriptional profiling with genetics to determine how the kss1 mapk signaling pathway controls dimorphic development in saccharomyces cerevisiae. this analysis identified dozens of transcripts that are regulated by the pathway, whereas previous work had identified only a single downstream target, ... | 1999 | 10535956 |
| reciprocal secretion of proteins by the bacterial type iii machines of plant and animal pathogens suggests universal recognition of mrna targeting signals. | bacterial pathogens of both animals and plants use type iii secretion machines to inject virulence proteins into host cells. although many components of the secretion machinery are conserved among different bacterial species, the substrates for their type iii pathways are not. the yersinia type iii machinery recognizes some secretion substrates via a signal that is encoded within the first 15 codons of yop mrna. these signals can be altered by frameshift mutations without affecting secretion of ... | 1999 | 10536009 |
| distribution of tetracycline resistance genes and transposons among phylloplane bacteria in michigan apple orchards. | the extent and nature of tetracycline resistance in bacterial populations of two apple orchards with no or a limited history of oxytetracycline usage were assessed. tetracycline-resistant (tc(r)) bacteria were mostly gram negative and represented from 0 to 47% of the total bacterial population on blossoms and leaves (versus 26 to 84% for streptomycin-resistant bacteria). a total of 87 isolates were screened for the presence of specific tc(r) determinants. tc(r) was determined to be due to the pr ... | 1999 | 10543801 |
| analysis of three clustered polygalacturonase genes in erwinia chrysanthemi 3937 revealed an anti-repressor function for the pecs regulator. | erwinia chrysanthemi 3937 secretes an arsenal of pectinolytic enzymes including several pectate lyases encoded by the pel genes. we characterized a novel cluster of pectinolytic genes consisting of the three adjacent genes pehv, pehw and pehx, whose products have polygalacturonase activity. the high similarity between the three genes suggests that they result from duplication of an ancestral gene. the transcription of pehv, pehw and pehx is dependent on several environmental conditions. they are ... | 1999 | 10564505 |
| genetic dissection of the outer membrane secretin puld: are there distinct domains for multimerization and secretion specificity? | linker and deletion mutagenesis and gene fusions were used to probe the possible domain structure of the dodecameric outer membrane secretin puld from the pullulanase secretion pathway of klebsiella oxytoca. insertions of 24 amino acids close to or within strongly predicted and highly conserved amphipathic beta strands in the c-terminal half of the polypeptide (the beta domain) abolished sodium dodecyl sulfate (sds)-resistant multimer formation that is characteristic of this protein, whereas ins ... | 1999 | 10572123 |
| a unique chitinase with dual active sites and triple substrate binding sites from the hyperthermophilic archaeon pyrococcus kodakaraensis kod1. | we have found that the hyperthermophilic archaeon pyrococcus kodakaraensis kod1 produces an extracellular chitinase. the gene encoding the chitinase (chia) was cloned and sequenced. the chia gene was found to be composed of 3,645 nucleotides, encoding a protein (1,215 amino acids) with a molecular mass of 134,259 da, which is the largest among known chitinases. sequence analysis indicates that chia is divided into two distinct regions with respective active sites. the n-terminal and c-terminal r ... | 1999 | 10583986 |
| requirement for phosphoglucose isomerase of xanthomonas campestris in pathogenesis of citrus canker. | a mutant (xt906) of xanthomonas campestris pv. citri, the causal agent of citrus canker, was induced by insertion of the transposon tn5tac1 and isolated. this mutant did not grow or elicit canker disease in citrus leaves but was still able to induce a hypersensitive response in a nonhost plant (the common bean). the mutant was also unable to grow on minimal medium containing fructose or glycerol as the sole carbon source. a 2.5-kb fragment of wild-type dna that complemented the mutant phenotype ... | 1999 | 10584018 |
| genetic analysis of a chromosomal region containing genes required for assimilation of allantoin nitrogen and linked glyoxylate metabolism in escherichia coli. | growth experiments with escherichia coli have shown that this organism is able to use allantoin as a sole nitrogen source but not as a sole carbon source. nitrogen assimilation from this compound was possible only under anaerobic conditions, in which all the enzyme activities involved in allantoin metabolism were detected. of the nine genes encoding proteins required for allantoin degradation, only the one encoding glyoxylate carboligase (gcl), the first enzyme of the pathway leading to glycerat ... | 1999 | 10601204 |
| cloning and characterization of the pseudomonas fluorescens atp-binding cassette exporter, hasdef, for the heme acquisition protein hasa. | two atp-binding cassette (abc) exporters are present in pseudomonas fluorescens no. 33; one is the recently reported aprdef system and the other is hasdef, which exports a heme acquisition protein, hasa. the hasdef genes were cloned by dna hybridization with a dna probe coding for the lipb protein, one of the components of the serratia marcescens abc exporter lip system. p. fluorescens hasa showed sequence identity of 40 to 49% with hasa proteins from pseudomonas aeruginosa and serratia marcesce ... | 1999 | 10601212 |
| a multifunctional atp-binding cassette transporter system from vibrio cholerae transports vibriobactin and enterobactin. | vibrio cholerae uses the catechol siderophore vibriobactin for iron transport under iron-limiting conditions. we have identified genes for vibriobactin transport and mapped them within the vibriobactin biosynthetic gene cluster. within this genetic region we have identified four genes, viup, viud, viug and viuc, whose protein products have homology to the periplasmic binding protein, the two integral cytoplasmic membrane proteins, and the atpase component, respectively, of other iron transport s ... | 1999 | 10601218 |
| performance of selected microbial pectinases on synthetic monomethyl-esterified di- and trigalacturonates. | two monomethyl esters of alpha-(1-4)-linked d-galacturonic dimers and three monomethyl esters of alpha-(1-4)-linked d-galacturonic acid trimers were synthesized chemically and further used as substrates in order to establish the substrate specificity of six different endopolygalacturonases from aspergillus niger, one exopolygalacturonase from aspergillus tubingensis, and four selected erwinia chrysanthemi pectinases; exopolygalacturonan hydrolase x (pehx), exopolygalacturonate lyase x (pelx), ex ... | 1999 | 10601263 |
| glycine betaine transport in lactococcus lactis is osmotically regulated at the level of expression and translocation activity. | microorganisms react upon hyperosmotic stress by accumulating compatible solutes. here we report that lactococcus lactis uses a transport system for glycine betaine that, contrary to earlier observations (d. molenaar et al., j. bacteriol. 175:5438-5444, 1993), is osmotically regulated at the levels of both expression and transport activity. | 2000 | 10613881 |
| expression of alcaligenes eutrophus flavohemoprotein and engineered vitreoscilla hemoglobin-reductase fusion protein for improved hypoxic growth of escherichia coli. | expression of the vhb gene encoding hemoglobin from vitreoscilla sp. (vhb) in several organisms has been shown to improve microaerobic cell growth and enhance oxygen-dependent product formation. the amino-terminal hemoglobin domain of the flavohemoprotein (fhp) of the gram-negative hydrogen-oxidizing bacterium alcaligenes eutrophus has 51% sequence homology with vhb. however, like other flavohemoglobins and unlike vhb, fhp possesses a second (carboxy-terminal) domain with nad(p)h and flavin aden ... | 2000 | 10618209 |
| alteration of the lipopolysaccharide structure affects the functioning of the xcp secretory system in pseudomonas aeruginosa. | pseudomonas aeruginosa secretes a wide range of hydrolytic enzymes into the external medium by the xcp secretion machinery. to better understand the role played by envelope constituents in the functioning of this type ii secretory system, we have studied the influence of lipopolysaccharide (lps) on the secretion of two extracellular enzymes, the elastase lasb and the lipase lipa. strains with defective lps decreased production of lasb and altered the secretion processes of both lasb and lipa wit ... | 2000 | 10633103 |
| two regions of epsl involved in species-specific protein-protein interactions with epse and epsm of the general secretion pathway in vibrio cholerae. | extracellular secretion of proteins via the type ii or general secretion pathway in gram-negative bacteria requires the assistance of at least 12 gene products that are thought to form a complex apparatus through which secreted proteins are translocated. although this apparatus is specifically required only for the outer membrane translocation step during transport across the bacterial cell envelope, it is believed to span both membranes. the epse, epsl, and epsm proteins of the type ii apparatu ... | 2000 | 10633109 |
| discovery of a nonclassical siderophore, legiobactin, produced by strains of legionella pneumophila. | the mechanisms by which legionella pneumophila, a facultative intracellular parasite and the agent of legionnaires' disease, acquires iron are largely unexplained. several earlier studies indicated that l. pneumophila does not elaborate siderophores. however, we now present evidence that supernatants from l. pneumophila cultures can contain a nonproteinaceous, high-affinity iron chelator. more specifically, when aerobically grown in a low-iron, chemically defined medium (cdm), l. pneumophila sec ... | 2000 | 10633110 |
| conversion of the vibrio fischeri transcriptional activator, luxr, to a repressor. | the vibrio fischeri luminescence (lux) operon is regulated by a quorum-sensing system that involves the transcriptional activator (luxr) and an acyl-homoserine lactone signal. transcriptional activation requires the presence of a 20-base inverted repeat termed the lux box at a position centered 42.5 bases upstream of the transcriptional start of the lux operon. luxr has proven difficult to study in vitro. a truncated form of luxr has been purified, and together with sigma(70) rna polymerase it c ... | 2000 | 10633117 |
| a gene encoding a novel multidomain beta-1,4-mannanase from caldibacillus cellulovorans and action of the recombinant enzyme on kraft pulp. | genomic walking pcr was used to obtained a 4,567-bp nucleotide sequence from caldibacillus cellulovorans. analysis of this sequence revealed that there were three open reading frames, designated orf1, orf2, and orf3. incomplete orf1 encoded a putative c-terminal cellulose-binding domain (cbd) homologous to members of cbd family iiib, while putative orf3 encoded a protein of unknown function. the putative mana protein encoded by complete mana orf2 was an enzyme with a novel multidomain structure ... | 2000 | 10653733 |
| an unusual pectate lyase from a bacillus sp. with high activity on pectin: cloning and characterization. | the gene pela encoding a pectate lyase from the strain bacillus sp. bp-23 was cloned and expressed in escherichia coli. the nucleotide sequence of a 1214 bp dna fragment containing pela gene was determined, revealing an orf of 666 nucleotides that encoded a protein of 23233 da. the deduced amino acid sequence of the encoded enzyme showed homology to pectate lyases a, b, c and d from fusarium solani, pel-3 and pelb from erwinia carotovora and pell from erwinia chrysanthemi. homology was also foun ... | 2000 | 10658655 |
| the cochliobolus carbonum snf1 gene is required for cell wall-degrading enzyme expression and virulence on maize. | the production of cell wall-degrading enzymes (wall depolymerases) by plant pathogenic fungi is under catabolite (glucose) repression. in saccharomyces cerevisiae, the snf1 gene is required for expression of catabolite-repressed genes when glucose is limiting. an ortholog of snf1, ccsnf1, was isolated from the maize pathogen cochliobolus carbonum, and ccsnf1 mutants of hc toxin-producing (tox2(+)) and hc toxin-nonproducing (tox2(-)) strains were created by targeted gene replacement. growth in vi ... | 2000 | 10662860 |
| characterization of sota and sotb, two erwinia chrysanthemi proteins which modify isopropyl-beta-d-thiogalactopyranoside and lactose induction of the escherichia coli lac promoter. | the expression, in escherichia coli, of variants of the erwinia chrysanthemi secretion genes outb and outs under the ptac promoter is toxic to the cells. during attempts to clone e. chrysanthemi genes able to suppress this toxicity, i identified two genes, sota and sotb, whose products are able to reduce the isopropyl-beta-d-thiogalactopyranoside (iptg) induction of the e. coli lac promoter. sota and sotb belong to two different families of the major facilitator superfamily. sota is a member of ... | 2000 | 10671456 |
| characterization of erwinia chrysanthemi py35 cel and pel gene existing in tandem and rapid identification of their gene products. | genomic dna of the phytopathogenic erwinia chrysanthemi py35 was partially digested with sau3ai, ligated into the bamhi site of pbluescript ii sk+, and introduced into e. coli. one clone that was able to hydrolyse carboxymethylcellulose and polygalacturonic acid was selected. a 2.9 kb fragment containing the pell1 gene (ppy300) and cel5z gene (ppy401) in tandem was subcloned and sequenced. the pell1 and cel5z genes had open reading frames of 1,278 bp and 1,281 bp encoding 425 and 426 amino acid ... | 2000 | 10679220 |
| association of the cytoplasmic membrane protein xpsn with the outer membrane protein xpsd in the type ii protein secretion apparatus of xanthomonas campestris pv. campestris. | an xps gene cluster composed of 11 open reading frames is required for the type ii protein secretion in xanthomonas campestris pv. campestris. immediately upstream of the xpsd gene, which encodes an outer membrane protein that serves as the secretion channel by forming multimers, there exists an open reading frame (previously designated orf2) that could encode a protein of 261 amino acid residues. its n-terminal hydrophobic region is a likely membrane-anchoring sequence. antibody raised against ... | 2000 | 10692359 |
| ssra (tmrna) plays a role in salmonella enterica serovar typhimurium pathogenesis. | escherichia coli ssra encodes a small stable rna molecule, tmrna, that has many diverse functions, including tagging abnormal proteins for degradation, supporting phage growth, and modulating the activity of dna binding proteins. here we show that ssra plays a role in salmonella enterica serovar typhimurium pathogenesis and in the expression of several genes known to be induced during infection. moreover, the phage-like attachment site, attl, encoded within ssra, serves as the site of integratio ... | 2000 | 10692360 |
| ph regulation of pectate lyase secretion modulates the attack of colletotrichum gloeosporioides on avocado fruits. | growth of colletotrichum gloeosporioides in pectolytic enzyme-inducing medium (peim) increased the ph of the medium from 3. 8 to 6.5. pectate lyase (pl) secretion was detected when the ph reached 5.8, and the level of secretion increased up to ph 6.5. pl gene (pel) transcript production began at ph 5.0 and increased up to ph 5.7. pl secretion was never detected when the ph of the inducing medium was lower than 5.8 or when c. gloeosporioides hyphae were transferred from pl-secreting conditions at ... | 2000 | 10698767 |
| transformation of acinetobacter sp. strain bd413(pfg4deltanptii) with transgenic plant dna in soil microcosms and effects of kanamycin on selection of transformants. | here we show that horizontal transfer of dna, extracted from transgenic sugar beets, to bacteria, based on homologous recombination, can occur in soil. restoration of a 317-bp-deleted nptii gene in acinetobacter sp. strain bd413(pfg4) cells incubated in sterile soil microcosms was detected after addition of nutrients and transgenic plant dna encoding a functional nptii gene conferring bacterial kanamycin resistance. selective effects of the addition of kanamycin on the population dynamics of aci ... | 2000 | 10698801 |
| microbial relatives of the seed storage proteins of higher plants: conservation of structure and diversification of function during evolution of the cupin superfamily. | this review summarizes the recent discovery of the cupin superfamily (from the latin term "cupa," a small barrel) of functionally diverse proteins that initially were limited to several higher plant proteins such as seed storage proteins, germin (an oxalate oxidase), germin-like proteins, and auxin-binding protein. knowledge of the three-dimensional structure of two vicilins, seed proteins with a characteristic beta-barrel core, led to the identification of a small number of conserved residues a ... | 2000 | 10704478 |
| purification, crystallization and x-ray analysis of crystals of pectate lyase a from exwinia chrysanthemi. | pectate lyase a is secreted by erwinia chrysanthemi and is a virulence factor for soft rot diseases in plants. crystals of pectate lyase a were obtained by vapor-diffusion techniques in the presence of polyethylene glycol. the crystals belong to the monoclinic space group p2(1), with unit-cell parameters a = 48.96, b = 148.86, c = 78.61 a, beta = 97.32 degrees. the crystals contain two protein molecules of 38 kda per asymmetric unit and diffract to 2.4 a using cu kalpha radiation. | 2000 | 10713524 |
| aiia, an enzyme that inactivates the acylhomoserine lactone quorum-sensing signal and attenuates the virulence of erwinia carotovora. | n-acylhomoserine lactones, known as autoinducers (ais), are widely conserved signal molecules present in quorum-sensing systems of many gram-negative bacteria. ais are involved in the regulation of diverse biological functions, including expression of pathogenic genes in the plant pathogens pseudomonas solanacearum, several erwinia species, and the human pathogen pseudomonas aeruginosa. a bacterial isolate, bacillus sp. 240b1, is capable of enzymatic inactivation of ais. the gene (aiia) for ai i ... | 2000 | 10716724 |
| secreted enzymatic activities of wild-type and pild-deficient legionella pneumophila. | legionella pneumophila, the agent of legionnaires' disease, is an intracellular pathogen of protozoa and macrophages. previously, we had determined that the legionella pild gene is involved in type iv pilus biogenesis, type ii protein secretion, intracellular infection, and virulence. since the loss of pili and a protease do not account for the infection defect exhibited by a pild-deficient strain, we sought to define other secreted proteins absent in the mutant. based upon the release of p-nitr ... | 2000 | 10722574 |
| mutations in the extracellular protein secretion pathway genes (eps) interfere with rugose polysaccharide production in and motility of vibrio cholerae. | vibrio cholerae is the causal organism of the diarrheal disease cholera. the rugose variant of v. cholerae is associated with the secretion of an exopolysaccharide. the rugose polysaccharide has been shown to confer increased resistance to a variety of agents, such as chlorine, bioacids, and oxidative and osmotic stresses. it also promotes biofilm formation, thereby increasing the survival of the bacteria in the aquatic environments. here we show that the extracellular protein secretion system ( ... | 2000 | 10722590 |
| identification of regions of the escherichia coli chromosome specific for neonatal meningitis-associated strains. | specific virulence factors associated with the pathogenesis of escherichia coli strains causing neonatal meningitis (ecnm), such as the k1 capsular polysaccharide, the s fimbriae, and the ibe10 protein, have been previously identified. however, some other yet unidentified factors are likely to be involved in the pathogenesis of ecnm. to identify specialized unique dna regions associated with ecnm virulence, we used the representational difference analysis technique. the genomes of two strains be ... | 2000 | 10722606 |
| the phytopathogenic bacteria erwinia carotovora infects drosophila and activates an immune response. | although drosophila possesses potent immune responses, little is known about the microbial pathogens that infect drosophila. we have identified members of the bacterial genus erwinia that induce the systemic expression of genes encoding antimicrobial peptides in drosophila larvae after ingestion. these erwinia strains are phytopathogens and use flies as vectors; our data suggest that these strains have also evolved mechanisms for exploiting their insect vectors as hosts. erwinia infections induc ... | 2000 | 10725405 |
| multiple interactions between pullulanase secreton components involved in stabilization and cytoplasmic membrane association of pule. | we report attempts to analyze interactions between components of the pullulanase (pul) secreton (type ii secretion machinery) from klebsiella oxytoca encoded by a multiple-copy-number plasmid in escherichia coli. three of the 15 pul proteins (b, h, and n) were found to be dispensable for pullulanase secretion. the following evidence leads us to propose that pule, pull, and pulm form a subcomplex with which pulc and pulg interact. the integral cytoplasmic membrane protein pull prevented proteolys ... | 2000 | 10735856 |
| identification of an operon required for ferrichrome iron utilization in vibrio cholerae. | mutagenesis of vibrio cholerae with tnphoa, followed by screening for fusions that were activated under low-iron conditions, led to the identification of seven independent fusion strains, each of which was deficient in the ability to utilize ferrichrome as a sole iron source for growth in a plate bioassay and had an insertion in genes encoding products homologous to escherichia coli fhua or fhud. expression of the gene fusions was independent of irgb but regulated by fur. we report here a map of ... | 2000 | 10735886 |
| production of pectate lyases and cellulases by chryseomonas luteola strain mfcl0 depends on the growth temperature and the nature of the culture medium: evidence for two critical temperatures. | several extracellular enzymes that are responsible for plant tissue maceration were detected in culture supernatant of the psychrotrophic bacterium chryseomonas luteola mfcl0. isoelectrofocusing experiments showed that pectate lyase (pl) activity resulted from the cumulative action of three major isoenzymes, designated pli, plii, and pliii. cellulolytic activity was also detected in culture supernatants. these enzymes exhibited different behaviors with respect to growth temperature. plii was not ... | 2000 | 10742239 |
| role of molybdate and other transition metals in the accumulation of protochelin by azotobacter vinelandii. | both molybdate and iron are metals that are required by the obligately aerobic organism azotobacter vinelandii to survive in the nutrient-limited conditions of its natural soil environment. previous studies have shown that a high concentration of molybdate (1 mm) affects the formation of a. vinelandii siderophores such that the tricatecholate protochelin is formed to the exclusion of the other catecholate siderophores, azotochelin and aminochelin. it has been shown previously that molybdate comb ... | 2000 | 10742245 |
| extracellular polysaccharide of erwinia chrysanthemi a350 and ribotyping of erwinia chrysanthemi spp. | erwinia chrysanthemi spp. are gram-negative bacterial phytopathogens causing soft rots in a number of plants. the structure of the extracellular polysaccharide (eps) produced by the e. chrysanthemi strain a350, which is a lacz- mutant of the wild type strain 3937, pathogenic to saintpaulia, has been determined using a combination of chemical and physical techniques including methylation analysis, low-pressure gel-filtration and anion-exchange chromatography, high-ph anion-exchange chromatography ... | 2000 | 10744334 |
| overproduction of the secretin outd suppresses the secretion defect of an erwinia chrysanthemi outb mutant. | outb is a component of the erwinia chrysanthemi out secretion machinery. homologues of outb have been described in two other bacteria, klebsiella oxytoca and aeromonas hydrophila, but their requirement in the secretion process seems to be different. study of outb topology with the blam topology probe suggests that it is an inner-membrane protein with a large periplasmic domain. however, fractionation experiments indicate that it could be associated with the outer membrane through its c-terminal ... | 2000 | 10746767 |
| quorum sensing in the plant pathogen erwinia carotovora subsp. carotovora: the role of expr(ecc). | the production of the main virulence determinants of the plant pathogen erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule n-(3-oxohexanoyl)-l-homoserine lactone (ohhl). ohhl is synthesized by the product of the expi/cari gene. linked to expi we found a gene encoding a putative transcriptional regulator of the luxr-family. this gene, expr(ecc), is transcribed convergently to the expi gene and the two open re ... | 2000 | 10755301 |
| evidence against a direct antimicrobial role of h2o2 in the infection of plants by erwinia chrysanthemi. | we have investigated the role of bacterial resistance to oxidative stress in pathogenesis. the oxyr gene from the pathogenic bacterium erwinia chrysanthemi has been characterized. it is closely related to that found in escherichia coli (88% overall amino acid identity). an e. chrysanthemi oxyr mutant strain was constructed by marker exchange. after induction with a sublethal dose of h2o2, this mutant was more sensitive to h2o2 and showed reduced levels of catalase and glutathione reductase activ ... | 2000 | 10755305 |
| protection from nitrosative stress by yeast flavohemoglobin. | yeast hemoglobin was discovered close to half a century ago, but its function has remained unknown. herein, we report that this flavohemoglobin protects saccharomyces cerevisiae from nitrosative stress. deletion of the flavohemoglobin gene (yhb1) abolished the nitric oxide (no)-consuming activity of yeast cells. levels of protein nitrosylation were more than 10-fold higher in yhb1 mutant yeast than in isogenic wild-type cells after incubation with no donors. growth of mutant cells was inhibited ... | 2000 | 10758168 |
| the pseudomonas syringae hrp pathogenicity island has a tripartite mosaic structure composed of a cluster of type iii secretion genes bounded by exchangeable effector and conserved effector loci that contribute to parasitic fitness and pathogenicity in plants. | the plant pathogenic bacterium pseudomonas syringae is divided into pathovars differing in host specificity, with p. syringae pv. syringae (psy) and p. syringae pv. tomato (pto) representing particularly divergent pathovars. p. syringae hrp/hrc genes encode a type iii protein secretion system that appears to translocate avr and hop effector proteins into plant cells. dna sequence analysis of the hrp/hrc regions in psy 61, psy b728a, and pto dc3000 has revealed a hrp pathogenicity island (pai) wi ... | 2000 | 10781092 |
| solution structure of the chitin-binding domain of bacillus circulans wl-12 chitinase a1. | the three-dimensional structure of the chitin-binding domain (chbd) of chitinase a1 (chia1) from a gram-positive bacterium, bacillus circulans wl-12, was determined by means of multidimensional heteronuclear nmr methods. chia1 is a glycosidase that hydrolyzes chitin and is composed of an n-terminal catalytic domain, two fibronectin type iii-like domains, and c-terminal chbd(chia1) (45 residues, ala(655)-gln(699)), which binds specifically to insoluble chitin. chbd(chia1) has a compact and globul ... | 2000 | 10788483 |
| a fluorometric assay for l-asparaginase activity and monitoring of l-asparaginase therapy. | the antineoplastic enzyme l-asparaginase is commonly used for the induction of remission in acute lymphoblastic leukemia (all). there is no simple method available for measuring the activity of this highly toxic drug. we incubated l-asparaginase from erwinia chrysanthemi with l-aspartic acid beta-(7-amido-4-methylcoumarin) and measured the release of 7-amino-4-methylcoumarin fluorometrically for 30-300 min. the rate of the hydrolysis of the substrate was linear over a 50-fold range of the concen ... | 2000 | 10805519 |
| differential regulation of plastidial and cytosolic isoforms of peptide methionine sulfoxide reductase in arabidopsis. | we report the characterization of two members of a gene family from arabidopsis that encode, respectively, cytosolic (cpmsr) and plastid-targeted (ppmsr) isoforms of the oxidative-stress-repair enzyme peptide methionine sulfoxide reductase. overexpression of these proteins in escherichia coli confirmed that each had pmsr enzyme activity with a synthetic substrate, n-acetyl-[(3)h]-methionine sulfoxide, or a biological substrate, alpha-1 proteinase inhibitor. the ppmsr was imported into intact chl ... | 2000 | 10806242 |
| expression and characterization of the chitin-binding domain of chitinase a1 from bacillus circulans wl-12. | chitinase a1 from bacillus circulans wl-12 comprises an n-terminal catalytic domain, two fibronectin type iii-like domains, and a c-terminal chitin-binding domain (chbd). in order to study the biochemical properties and structure of the chbd, chbd(chia1) was produced in escherichia coli using a pet expression system and purified by chitin affinity column chromatography. purified chbd(chia1) specifically bound to various forms of insoluble chitin but not to other polysaccharides, including chitos ... | 2000 | 10809681 |
| secretion of the caulobacter crescentus s-layer protein: further localization of the c-terminal secretion signal and its use for secretion of recombinant proteins. | the secretion signal of the caulobacter crescentus s-layer protein (rsaa) was localized to the c-terminal 82 amino acids of the molecule. protein yield studies showed that 336 or 242 c-terminal residues of rsaa mediated secretion of >50 mg of a cellulase passenger protein per liter to the culture fluids. | 2000 | 10809716 |
| elisa to evaluate plasma anti-asparaginase igg concentrations in patients with acute lymphoblastic leukemia. | the development of antibodies to asparaginase may attenuate the pharmacologic effect of asparaginase treatment, may be associated with hypersensitivity reactions, and may necessitate switching to a different commercial asparaginase preparation for current or future therapy. thus, development of an elisa for measurement of anti-asparaginase antibody levels is important in the clinical setting. an anti-asparaginase antibody reference was established by screening 65 plasma samples from six patients ... | 2000 | 10821949 |
| detection of pseudomonas savastanoi pv. savastanoi in olive plants by enrichment and pcr. | the sequence of the gene iaal of pseudomonas savastanoi ew2009 was used to design primers for pcr amplification. the iaal-derived primers directed the amplification of a 454-bp fragment from genomic dna isolated from 70 strains of p. savastanoi, whereas genomic dna from 93 non-p. savastanoi isolates did not yield this amplified product. a previous bacterial enrichment in the semiselective liquid medium pvf-1 improved the pcr sensitivity level, allowing detection of 10 to 100 cfu/ml of plant extr ... | 2000 | 10831456 |
| a functional-phylogenetic classification system for transmembrane solute transporters. | a comprehensive classification system for transmembrane molecular transporters has been developed and recently approved by the transport panel of the nomenclature committee of the international union of biochemistry and molecular biology. this system is based on (i) transporter class and subclass (mode of transport and energy coupling mechanism), (ii) protein phylogenetic family and subfamily, and (iii) substrate specificity. almost all of the more than 250 identified families of transporters in ... | 2000 | 10839820 |
| thiol-disulfide exchange is involved in the catalytic mechanism of peptide methionine sulfoxide reductase. | peptide methionine sulfoxide reductase (msra; ec ) reverses the inactivation of many proteins due to the oxidation of critical methionine residues by reducing methionine sulfoxide, met(o), to methionine. msra activity is independent of bound metal and cofactors but does require reducing equivalents from either dtt or a thioredoxin-regenerating system. in an effort to understand these observations, the four cysteine residues of bovine msra were mutated to serine in a series of permutations. an an ... | 2000 | 10841552 |
| fermentations of pectin-rich biomass with recombinant bacteria to produce fuel ethanol. | pectin-rich residues from sugar beet processing contain significant carbohydrates and insignificant amounts of lignin. beet pulp was evaluated for conversion to ethanol using recombinant bacteria as biocatalysts. hydrolysis of pectin-rich residues followed by ethanolic fermentations by yeasts has not been productive because galacturonic acid and arabinose are not fermentable to ethanol by these organisms. the three recombinant bacteria evaluated in this study, escherichia coli strain ko11, klebs ... | 2000 | 10849785 |
| secretion of nucleoside diphosphate kinase by mucoid pseudomonas aeruginosa 8821: involvement of a carboxy-terminal motif in secretion. | nucleoside diphosphate kinase (ndk) is a ubiquitous enzyme which functions in balancing the nucleotide pool of the cell. we have recently reported that in addition to being intracellular in both mucoid and nonmucoid pseudomonas aeruginosa, ndk is also secreted into the extracellular environment by mucoid p. aeruginosa cells. this secreted ndk has biochemical activity similar to the intracellular ndk and is 16 kda in size. to demonstrate that ndk is indeed secreted and to localize the secretion m ... | 2000 | 10851000 |
| a regulatory rna (prrb rna) modulates expression of secondary metabolite genes in pseudomonas fluorescens f113. | the gacs-gaca two-component signal transduction system, which is highly conserved in gram-negative bacteria, is required for the production of exoenzymes and secondary metabolites in pseudomonas spp. screening of a pseudomonas fluorescens f113 gene bank led to the isolation of a previously undefined locus which could restore secondary metabolite production to both gacs and gaca mutants of f113. sequence analysis of this locus demonstrated that it did not contain any obvious pseudomonas protein-c ... | 2000 | 10869066 |
| influence of deletions within domain ii of exotoxin a on its extracellular secretion from pseudomonas aeruginosa. | pseudomonas aeruginosa is a gram-negative bacterium that secretes many proteins into the extracellular medium via the xcp machinery. this pathway, conserved in gram-negative bacteria, is called the type ii pathway. the exoproteins contain information in their amino acid sequence to allow targeting to their secretion machinery. this information may be present within a conformational motif. the nature of this signal has been examined for p. aeruginosa exotoxin a (pe). previous studies failed to id ... | 2000 | 10869085 |
| overproduction in escherichia coli of the pectin methylesterase a from erwinia chrysanthemi 3937: one-step purification, biochemical characterization, and production of polyclonal antibodies. | pectin methylesterase a (ec 3.1.1.11), one of the pathogenicity factors of erwinia chrysanthemi strain 3937, was purified to homogeneity using one-step chromatography on cross-linked pectate. the purified protein showed maximum activity at ph 8-9, 50 degrees c, 50-100 mm monovalent cations or 5-10 mm divalent cations, and on a 50% esterified pectin. a particular effect of ca2+ and zn2+ on pmea activity, due to the formation of a pectin gel, was observed. a km value of 0.03% and 0.051% was determ ... | 2000 | 10872083 |
| a novel beta-glucoside-specific pts locus from streptococcus mutans that is not inhibited by glucose. | a regulon from streptococcus mutans that plays a role in the utilization of beta-glucosides has been isolated, sequenced and subjected to sequence analysis. this regulon encodes a beta-glucoside-specific enzyme ii (eii) component (bglp) of the phosphoenolpyruvate-dependent phosphotransferase system (pts) and a phospho-beta-glucosidase (bgla) which is responsible for the breakdown of the phospho-beta-glucosides within the cell. both the bglp and bgla gene products have significant similarity with ... | 2000 | 10878120 |
| cloning and sequencing of pel gene responsible for cmcase activity from erwinia chrysanthemi py35. | the phytopathogenic bacterium erwinia chrysanthemi secretes multiple isozymes of plant cell wall disrupting enzymes such as pectate lyase and endoglucanase. we cloned genomic dna from erwinia chrysanthemi py35. one of the e. coli xl1-blue clones contained a 5.1-kb bamhi fragment and hydrolyzed carboxymethyl cellulose and polygalacturonic acid. by subsequent subcloning, we obtained a 2.9-kb fragment (ppy100) that contained the pel gene responsible for cmcase and pectate lyase activities. the pel ... | 2000 | 10879460 |
| cloning and sequencing of cel5z gene from erwinia chrysanthemi py35. | the phytopathogenic bacterium erwinia chrysanthemi (ech) secretes multiple isozymes of plant cell wall disrupting enzymes such as pectate lyase and endoglucanases. we cloned genomic dna from ech py35 digested with sau3ai and ligated into pbluescript ii sk+. one of the e. coli xl1-blue clones had the ability to hydrolyze carboxymethyl cellulose and polygalacturonic acid. by subsequent subcloning from this 2.9 kb fragment, we obtained a 2.0 kb (ppy401), designated cel5z, which had the activity of ... | 2000 | 10901164 |
| crystal structure of escherichia coli cyay protein reveals a previously unidentified fold for the evolutionarily conserved frataxin family. | friedreich ataxia is an autosomal recessive neurodegenerative disease caused by defects in the frda gene, which encodes a mitochondrial protein called frataxin. frataxin is evolutionarily conserved, with homologs identified in mammals, worms, yeast, and bacteria. the cyay proteins of gamma-purple bacteria are believed to be closely related to the ancestor of frataxin. in this study, we have determined the crystal structure of the cyay protein from escherichia coli at 1.4-a resolution. it reveals ... | 2000 | 10908679 |
| identification and characterization of a membrane permease involved in iron-hydroxamate transport in staphylococcus aureus. | staphylococcus aureus was shown to transport iron complexed to a variety of hydroxamate type siderophores, including ferrichrome, aerobactin, and desferrioxamine. an s. aureus mutant defective in the ability to transport ferric hydroxamate complexes was isolated from a tn917-ltv1 transposon insertion library after selection on iron-limited media containing aerobactin and streptonigrin. chromosomal dna flanking the tn917-ltv1 insertion was identified by sequencing of chromosomal dna isolated from ... | 2000 | 10913070 |
| functional characterization of the hasa(pf) hemophore and its truncated and chimeric variants: determination of a region involved in binding to the hemophore receptor. | hemophores are secreted by several gram-negative bacteria (serratia marcescens, pseudomonas aeruginosa, pseudomonas fluorescens, and yersinia pestis) and form a family of homologous proteins. unlike the s. marcescens hemophore (hasa(sm)), the p. fluorescens hemophore hasa(pf) has an additional region of 12 residues located immediately upstream from the c-terminal secretion signal. we show that hasa(pf) undergoes a c-terminal cleavage which removes the last 21 residues when secreted from p. fluor ... | 2000 | 10913071 |
| regulation of expression of the yiaklmnopqrs operon for carbohydrate utilization in escherichia coli: involvement of the main transcriptional factors. | the yiaklmnopqrs (yiak-s) gene cluster of escherichia coli is believed to be involved in the utilization of a hitherto unknown carbohydrate which generates the intermediate l-xylulose. transcription of yiak-s as a single message from the unique promoter found upstream of yiak is proven in this study. the 5' end has been located at 60 bp upstream from the atg. expression of the yiak-s operon is controlled in the wild-type strain by a repressor encoded by yiaj. no inducer molecule of the yiak-s op ... | 2000 | 10913096 |
| a genomic sample sequence of the entomopathogenic bacterium photorhabdus luminescens w14: potential implications for virulence. | photorhabdus luminescens is a pathogenic bacterium that lives in the guts of insect-pathogenic nematodes. after invasion of an insect host by a nematode, bacteria are released from the nematode gut and help kill the insect, in which both the bacteria and the nematodes subsequently replicate. however, the bacterial virulence factors associated with this "symbiosis of pathogens" remain largely obscure. in order to identify genes encoding potential virulence factors, we performed approximately 2,00 ... | 2000 | 10919786 |
| structure and function of pectic enzymes: virulence factors of plant pathogens. | the structure and function of erwinia chrysanthemi pectate lysase c, a plant virulence factor, is reviewed to illustrate one mechanism of pathogenesis at the molecular level. current investigative topics are discussed in this paper. | 2000 | 10922032 |
| pseudomonas syringae hrp type iii secretion system and effector proteins. | pseudomonas syringae is a member of an important group of gram-negative bacterial pathogens of plants and animals that depend on a type iii secretion system to inject virulence effector proteins into host cells. in p. syringae, hrp/hrc genes encode the hrp (type iii secretion) system, and avirulence (avr) and hrp-dependent outer protein (hop) genes encode effector proteins. the hrp/hrc genes of p. syringae pv syringae 61, p. syringae pv syringae b728a, and p. syringae pv tomato dc3000 are flanke ... | 2000 | 10922033 |
| plants and animals share functionally common bacterial virulence factors. | by exploiting the ability of pseudomonas aeruginosa to infect a variety of vertebrate and nonvertebrate hosts, we have developed model systems that use plants and nematodes as adjuncts to mammalian models to help elucidate the molecular basis of p. aeruginosa pathogenesis. our studies reveal a remarkable degree of conservation in the virulence mechanisms used by p. aeruginosa to infect hosts of divergent evolutionary origins. | 2000 | 10922040 |
| a new high-alkaline and high-molecular-weight pectate lyase from a bacillus isolate: enzymatic properties and cloning of the gene for the enzyme. | a pectate lyase (pel; pectate transeliminase: ec4.2.2.2.), designated pel-15h, was found in an alkaline culture of bacillus sp. strain ksm-p15 and purified to homogeneity by sequential column chromatographies. the molecular weight of the enzyme determined by sds-polyacrylamide gel electrophoresis was approximately 70,000 and the pi was around ph 4.6. pel-15h randomly trans-eliminated polygalacturonate in the presence of ca2+ ions, and the maximum activity was observed at ph 11.5 and at 55 degree ... | 2000 | 10923781 |
| achromobactin, a new citrate siderophore of erwinia chrysanthemi. | the structure of a citrate siderophore named achromobactin isolated from the culture medium of erwinia chrysanthemi was elucidated by spectroscopic methods and chemical degradation. | 2000 | 10928541 |
| characterization of a tonb mutation in erwinia chrysanthemi 3937: tonb(ech) is a member of the enterobacterial tonb family. | the pectinolytic enterobacterium erwinia chrysanthemi 3937 causes a systemic disease in its natural host, the african violet (saintpaulia: ionantha). it produces two structurally unrelated siderophores, chrysobactin and achromobactin. chrysobactin makes a large contribution to invasive growth of the bacterium in its host. insertion mutants of a chrysobactin-defective strain were constructed and screened on the universal cas-agar medium used for siderophore detection. a set of mutants affected in ... | 2000 | 10931909 |
| external ph: an environmental signal that helps to rationalize pel gene duplication in erwinia chrysanthemi. | the phytopathogenic bacterium erwinia chrysanthemi produces five major pectate lyases that are key virulence factors in soft-rot disease development. using transcriptional fusions, we studied the regulation of pela, peld, and pele gene expression as a function of variation of the external ph. pela and peld were expressed when bacteria were grown in an acidic medium while pele was transcribed only in basic medium. using phenol red, we observed that, in chicory leaves, ph value of infected tissue ... | 2000 | 10939260 |
| bacterial quorum sensing in pathogenic relationships. | 2000 | 10948095 | |
| up-regulation of both intimin and eae-independent adherence of shiga toxigenic escherichia coli o157 by ler and phenotypic impact of a naturally occurring ler mutation. | shiga toxigenic escherichia coli (stec) strains are important human pathogens which are capable of causing diarrhea, hemorrhagic colitis, and the potentially fatal hemolytic-uremic syndrome (hus). an important virulence trait of certain stec strains, such as those belonging to serogroup o157, is the capacity to produce attaching and effacing (a/e) lesions on enterocytes, a property encoded by the locus for enterocyte effacement (lee). lee contains the eae gene, which encodes intimin, an outer me ... | 2000 | 10948164 |
| the redox-sensitive transcriptional activator oxyr regulates the peroxide response regulon in the obligate anaerobe bacteroides fragilis. | the peroxide response-inducible genes ahpcf, dps, and katb in the obligate anaerobe bacteroides fragilis are controlled by the redox-sensitive transcriptional activator oxyr. this is the first functional oxidative stress regulator identified and characterized in anaerobic bacteria. oxyr and dps were found to be divergently transcribed, with an overlap in their respective promoter regulatory regions. b. fragilis oxyr and dps proteins showed high identity to homologues from a closely related anaer ... | 2000 | 10960088 |
| plant genome complexity may be a factor limiting in situ the transfer of transgenic plant genes to the phytopathogen ralstonia solanacearum. | the development of natural competence by bacteria in situ is considered one of the main factors limiting transformation-mediated gene exchanges in the environment. ralstonia solanacearum is a plant pathogen that is also a naturally transformable bacterium that can develop the competence state during infection of its host. we have attempted to determine whether this bacterium could become the recipient of plant genes. we initially demonstrated that plant dna was released close to the infecting ba ... | 2000 | 10966449 |
| erwinia chrysanthemi strains cause death of human gastrointestinal cells in culture and express an intimin-like protein. | the bacterium erwinia chrysanthemi is a model plant pathogen, responsible for causing cell death in plant tissue. cell-wall depolymerizing enzymes and avirulence proteins essential for parasitism by this bacterium utilize dedicated type ii and type iii secretion systems, respectively. although e. chrysanthemi is not recognized as a mammalian pathogen, we have observed that the bacterium can adhere to, cause an oxidative stress response in and kill cultured human adenocarcinoma cells. these bacte ... | 2000 | 10981694 |
| gene conservation and loss in the muts-rpos genomic region of pathogenic escherichia coli. | the extent and nature of dna polymorphism in the muts-rpos region of the escherichia coli genome were assessed in 21 strains of enteropathogenic e. coli (epec) and enterohemorrhagic e. coli (ehec) and in 6 strains originally isolated from natural populations. the intervening region between muts and rpos was amplified by long-range pcr, and the resulting amplicons varied substantially in length (7.8 to 14.2 kb) among pathogenic groups. restriction maps based on five enzymes and sequence analysis ... | 2000 | 10986240 |
| synergistic hydrolysis of carboxymethyl cellulose and acid-swollen cellulose by two endoglucanases (celz and cely) from erwinia chrysanthemi. | erwinia chrysanthemi produces a battery of hydrolases and lyases which are very effective in the maceration of plant cell walls. although two endoglucanases (celz and cely; formerly egz and egy) are produced, celz represents approximately 95% of the total carboxymethyl cellulase activity. in this study, we have examined the effectiveness of cely and celz alone and of combinations of both enzymes using carboxymethyl cellulose (cmc) and amorphous cellulose (acid-swollen cellulose) as substrates. s ... | 2000 | 11004164 |
| alteration of a single tryptophan residue of the cellulose-binding domain blocks secretion of the erwinia chrysanthemi cel5 cellulase (ex-egz) via the type ii system. | cel5 (formerly known as endoglucanase z) of erwinia chrysanthemi is secreted by the out type ii pathway. previous studies have shown that the catalytic domain (cd), linker region (lr) and cellulose-binding domain (cbd) each contain information needed for secretion. the aim of this work was to further investigate the secretion-related information present in the cbd(cel5). firstly(, )deleting a surface-exposed flexible loop had no effect on secretion. this indicated that some structural freedom is ... | 2000 | 11023779 |
| pseudobactin biogenesis in the plant growth-promoting rhizobacterium pseudomonas strain b10: identification and functional analysis of the l-ornithine n(5)-oxygenase (psba) gene. | pseudobactin(b10), the fluorescent siderophore produced by the rhizobacterium pseudomonas strain b10, contains the hydroxamate ligand d-n(5)-hydroxyornithine (d-n(5)-oh-orn). we cloned the l-orn n(5)-oxygenase (psba) gene from a genomic library of pseudomonas strain b10 and demonstrated that psba is involved in the conversion of l-orn to its n(5)-oh derivative. psba shows significant similarity to microbial omega-amino acid hydroxylases containing flavin adenine dinucleotide and nadp cofactor-bi ... | 2000 | 11029447 |
| functional implications of the beta-helical protein fold: differences in chemical and thermal stabilities of erwinia chrysanthemi ec16 pectate lyases b, c, and e. | colonization of plant tissue by the phytopathogen erwinia chrysanthemi ec16 is aided by the activities of the pectate lyase isozymes (pls), which depolymerize the polygalacturonic acid component (pga) of plant cell walls. the bacterium secretes four pectate lyases (pla, plb, plc, and ple), two of which, plc and ple, have been shown to fold into a similar domain motif, the beta-helix. to understand the rationale behind the evolution and retention of these isoforms, the susceptibilities of pectate ... | 2000 | 11032414 |
| molecular cloning and analysis of a putative siderophore abc transporter from staphylococcus aureus. | from a mass-excised staphylococcus aureus lambdazapii expression library, we cloned an operon encoding a novel abc transporter with significant homology to bacterial siderophore transporter systems. the operon encodes four genes designated ssta, -b, -c, and -d encoding two putative cytoplasmic membrane proteins (ssta and sstb), an atpase (sstc), and a membrane-bound 38-kda lipoprotein (sstd). the sst operon is preceded by two putative fur boxes, which indicated that expression of the sst operon ... | 2000 | 11035736 |
| complete nucleotide sequence of ubiquitous plasmid pea29 from erwinia amylovora strain ea88: gene organization and intraspecies variation. | the complete sequence of plasmid pea29 from erwinia amylovora strain ea88 consists of 28,185 bp with a 50.2% g+c content. as deletions and insertions were detected in other derivatives of pea29, its size actually varied from 27.6 to 34.9 kb. thirteen open reading frames that encoded predicted proteins with similarities to known proteins from other bacteria were identified along with two open reading frames related to hypothetical proteins found in genbank and six open reading frames with no simi ... | 2000 | 11055941 |
| purification and properties of an enzyme capable of degrading the sheath of sphaerotilus natans. | microorganisms which can degrade and grow on the purified sheath of a sheathed bacterium sphaerotilus natans were collected from soil and river water. two bacterial strains were isolated from the soil and designated strains tb and tk. both strains are rod shaped, negatively stained by gram staining, facultatively anaerobic, and formed ellipsoidal endospores. these characteristics suggested that the isolates belong to the genus paenibacillus, according to ash et al. (c. ash, f. g. priest, and m. ... | 2000 | 11055955 |