| homology of the gene coding for outer membrane lipoprotein within various gram-negative bacteria. | the mrna for a major outer membrane lipoprotein from escherichia coli was found to hybridize specifically with one of the ecori and one of the hindiii restriction endonuclease-generated fragments of total dna from nine bacteria in the family enterobacteriaceae: e. coli, shigella dysenteriae, salmonella typhimurium, citrobacter freundii, klebsiella aerogenes, enterobacter aerogenes, edwardsiella tarda, serratia marcescens, and erwinia amylovora. however, among the enterobacteriaceae, dna from two ... | 1979 | 104972 |
| transfer of episome f'lac+ and chromosomal trp+ genes from erwinia amylovora to salmonella typhimurium. | the f'lac+ episome of escherichia coli origin was transferred by conjugation with frequencies of 10(-7) to 10(-5) from erwinia amylovora to 14 out of 15 salmonella typhimurium trp female parents. the chromosomal trp+ genes were transferred with frequencies of 10(-7) to 10(-6) only to one trpb and 2 trpd female parents, which have a point mutation in the 2nd and fourth structural genes, respectively, of the tryptophan operon. the transferred male trp+ genes became integrated at the selected sites ... | 1977 | 330120 |
| enzymatic degradation of polygalacturonic acid by yersinia and klebsiella species in relation to clinical laboratory procedures. | as scored by several specified plating procedures, clinical and environmental strains of yersinia enterocolitica, yersinia pseudotuberculosis, and klebsiella pneumoniae "oxytocum" showed detectable, albeit generally weak, ability to digest polygalacturonic (pectic) acid. none of these bacterial strains had the vigorous and rapid pectolytic activity on these polygalacturonic acid-containing media that is typical of soft-rot erwinia species, although some of the oxytocum strains came fairly close. ... | 1977 | 334794 |
| isolation and characterization of hfr strains of erwinia amylovora. | hfr strains (hfr 159 and its derivatives, hfr 160 and hfr 161) were constructed from erwinia amylovora icpb ea178 by introducing an escherichia coli f'his+ plasmid and then selecting for integration of f'his+ after treatment with acridine orange. the hfr strains were relatively stable upon repeated transfers on nonselective media. interrupted mating experiments and analyses of inheritance of unselected markers showed that his+ is transferred by hfr 159 as the proximal marker at a relatively high ... | 1978 | 638897 |
| unusual susceptibility of erwinia amylovora to antibacterial agents in relation to the barrier function of its cell envelope. | wild-type strains of the bacterial phytopathogen erwinia amylovora (the cause of fire blight disease of apples and pears) are markedly susceptible to novobiocin, deoxycholate, and sodium dodecyl (= lauryl) sulfate. the inhibitory concentration, expressed as the concentration causing a 99% inhibition of growth, of these three antibacterial agents were 15 to 100, 40 to 800, and 50 to 800 mug/ml, respectively, depending on the e. amylovora strain. growth of strains of other erwinia spp. and salmone ... | 1977 | 879740 |
| zeatin ribonucleosides in the transfer ribonucleic acid of rhizobium leguminosarum, agrobacterium tumefaciens, corynebacterium fascians, and erwinia amylovora. | until recently, the presence in transfer ribonucleic acid (trna) of the hydroxylated cytokinin ribosylzeatin [n6-(4-hydroxy-3-methylbut-2-enyl)adenosine]was thought to be unique to higher plants. this extension of work from several laboratories indicates the presence of 2-methylthioribosylzeatin in the trna of the plant-associated bacteria rhizobium leguminosarum, agrobacterium tumefaciens, and corynebacterium fascians, but not in that of erwinia amylovora. this cytokinin has the cis configurati ... | 1977 | 893341 |
| in vitro and in vivo interactions between erwinia amylovora and related saprophytic bacteria. | under carefully controlled laboratory conditions, a highly virulent strain of erwinia amylovora coinhabited susceptible host tissues with a yellow saprophytic bacterium, which was invariably isolated from fire blight infected trees, with or without producing symptoms of the disease depending on the status of a number of environmental factors, both climatic and physiological. in particular, variation of temperature and sucrose concentration determined, independently, the equilibrium of a readily ... | 1975 | 1116037 |
| variation in the activity levels of selected enzymes of erwinia amylovora 595 in response to changes in dissolved oxygen tension and growth rate of d-glucose-limited chemostat cultures. | chemostat cultures of erwinia amylovora 595, grown in mineral salts-nicotinic acid medium at 30 degrees c, and limited by d-glucose concentrations in the presence of dissolved oxygen tensions (d.o.t.) greater than about 6mm hg, became limited by oxygen availability below about 4 mm hg. this latter limitation was accompanied by a marked increase in acid production as the d.o.t. was depressed. the transition between d-glucose- and oxygen-limitation was also characterized by a maximum in succinate ... | 1975 | 1116045 |
| conjugational transfer of genes determining plant virulence in erwinia amylovora. | a stable virulent donor strain (ea 178r1-99) of erwinia amylovora can transfer, by conjugation during a 3-h mating period, the gene or genes which determine(s) plant virulence to avirulent recipient strains (ea178-m64s1 and ea178-m173s1) of escherichia amylovora. the virulence of over 200 recombinant clones was tested; they all were as virulent on immature bartlett pear fruits (and, in the smaller series of strains tested, also, on pyracantha twigs) as was the parent donor strain. although the a ... | 1975 | 1126916 |
| development and properties of streptomycin resistant cultures of erwinia amylovora dervied from english isolates. | | 1975 | 1206023 |
| role of antibiotic production by erwinia herbicola eh252 in biological control of erwinia amylovora. | erwinia herbicola eh252 is a nonpathogenic epiphytic bacterium that reduces fire blight incidence when sprayed onto apple blossoms before inoculation with erwinia amylovora, the causal agent of fire blight. eh252 was found to produce on minimal medium an antibiotic that inhibited the growth of e. amylovora. this antibiotic was inactivated by histidine but not by fe(ii), was sensitive to proteolytic enzymes, and showed a narrow host range of activity. to determine the role of this antibiotic in t ... | 1992 | 1314801 |
| site-directed and transposon-mediated mutagenesis with pfd-plasmids by electroporation of erwinia amylovora and escherichia coli cells. | the suicide plasmid pfda31-tn5 was constructed to mutagenize erwinia amylovora and escherichia coli strains by electorporation. this vector carries the bacteriophage fd replication origin, a beta-lactamase gene and the transposon tn5. for propagation the plasmid depends on host cells producing fd gene-2 protein. electroporation of e.amylovora or e.coli cells with plasmid pfda31-tn5 yielded more than 10(4) transposition events per micrograms dna. we have produced and characterized transposon muta ... | 1992 | 1317549 |
| localization of transposon insertions in pathogenicity mutants of erwinia amylovora and their biochemical characterization. | transposon tn5, on a mobilizable cole1 plasmid, on a ti plasmid derepressed for bacterial transfer, and on the bacteriophage fd genome, was used to construct pathogenicity mutants of the fire blight pathogen erwinia amylovora. eleven nonpathogenic mutants were isolated from 1600 independent mutants screened. these mutants were divided into three types: auxotrophs, exopolysaccharide (eps)-deficient mutants and a mutant of the dsp phenotype. according to their insertion sites the tn5 mutants were ... | 1992 | 1322951 |
| expression of erwinia amylovora hrp genes in response to environmental stimuli. | seven hrp loci that are essential for the hypersensitive reaction elicited by erwinia amylovora were transcriptionally fused with a derivative of transposon tn5, containing the promoterless escherichia coli beta-glucuronidase reporter gene. the seven hrp fusions were used to monitor expression of the hrp loci in vitro and in planta. no significant expression was detected in rich medium for any of the fusions. however, five of them were expressed highly in planta and in inducing medium that conta ... | 1992 | 1372313 |
| hrp genes of pseudomonas solanacearum are homologous to pathogenicity determinants of animal pathogenic bacteria and are conserved among plant pathogenic bacteria. | the majority of bacterial plant diseases are caused by members of three bacterial genera, pseudomonas, xanthomonas, and erwinia. the identification and characterization of mutants that have lost the abilities to provoke disease symptoms on a compatible host and to induce a defensive hypersensitive reaction (hr) on an incompatible host have led to the discovery of clusters of hrp genes (hypersensitive reaction and pathogenicity) in phytopathogenic bacteria from each of these genera. here, we repo ... | 1992 | 1472716 |
| sensitive and species-specific detection of erwinia amylovora by polymerase chain reaction analysis. | detection and identification of the fire blight pathogen, erwinia amylovora, can be accurately done by polymerase chain reaction (pcr) analysis in less than 6 h. two oligomers derived from a 29-kb plasmid which is common to all strains of e. amylovora were used to amplify a 0.9-kb fragment of the plasmid. by separation of the pcr products on agarose gel, this fragment wa specifically detected when e. amylovora dna was present in the amplification assay. it was not found when dna from other plant ... | 1992 | 1482178 |
| biolistic transformation of prokaryotes: factors that affect biolistic transformation of very small cells. | five bacterial species were transformed using particle gun-technology. no pretreatment of cells was necessary. physical conditions (helium pressure, target cell distance and gap distance) and biological conditions (cell growth phase, osmoticum concentration, and cell density) were optimized for biolistic transformation of escherichia coli and these conditions were then used to successfully transform agrobacterium tumefaciens, erwinia amylovora, erwinia stewartii and pseudomonas syringae pv. syri ... | 1992 | 1556553 |
| harpin, elicitor of the hypersensitive response produced by the plant pathogen erwinia amylovora. | a proteinaceous elicitor of the plant defense reaction known as the hypersensitive response was isolated from erwinia amylovora, the bacterium that causes fire blight of pear, apple, and other rosaceous plants. the elicitor, named harpin, is an acidic, heat-stable, cell-envelope-associated protein with an apparent molecular weight of 44 kilodaltons. harpin caused tobacco leaf lamina to collapse and caused an increase in the ph of bathing solutions of suspension-cultured tobacco cells. the gene e ... | 1992 | 1621099 |
| cloning of a large gene cluster involved in erwinia amylovora cfbp1430 virulence. | phage mudiipr13 insertional mutagenesis of erwinia amylovora cfbp1430 allowed us to isolate 6900 independent cmr mutants. the frequencies of different auxotrophs in this population indicated that mudiipr13 had inserted randomly in e. amylovora. screening of 3500 cmr mutants on (i) apple calli and (ii) pear and apple seedlings led to the isolation of 19 non-pathogenic prototrophic single mutants, four of which expressed a lacz+ hybrid protein. expression of the fusion proteins was temperature sen ... | 1990 | 2117695 |
| the rcsa gene from erwinia amylovora: identification, nucleotide sequence, and regulation of exopolysaccharide biosynthesis. | rcsa is a positive activator of extracellular polysaccharide synthesis in the enterobacteriaceae. a cosmid clone containing the rcsa gene from erwinia amylovora was identified by its ability to restore mucoidy to an e. stewartii rcsa mutant. the rcsa gene was subcloned on a 2.2-kilobase hindiii-psti fragment that hybridized with an e. stewartii rcsa probe and complemented e. stewartii and escherichia coli rcsa mutants. in addition, the cloned e. amylovora rcsa gene stimulated expression of cps:: ... | 1990 | 2131100 |
| bacteriophage mu as a genetic tool to study erwinia amylovora pathogenicity and hypersensitive reaction on tobacco. | erwinia amylovora 1430 was shown to be sensitive to mu g(-) particles. infection resulted either in lytic development or in lysogenic derivatives with insertion of the mu genome at many sites in the bacterial chromosome. we used the mu d1bx::tn9 (lac apr cmr) derivative, called mu dx, to identify mutants affected in pathogenicity and in their ability to induce a hypersensitive reaction (hr) on tobacco plants. inoculation of 1,400 lysogenic derivatives on apple root calli led to the identificatio ... | 1990 | 2137121 |
| characterization of a 56-kb plasmid of erwinia amylovora ea322: its noninvolvement in pathogenicity. | a plasmid from erwinia amylovora strain ea322, pcpp60, was studied for its involvement in the phytopathogenicity of this strain. eviction through incompatibility and curing with acridine orange did not affect the pathogenic capability of ea322. the plasmid was characterized as self-transmissible with a narrow host range. hybridization of its origin of replication with plasmids of different incompatibility groups revealed affiliation with incf. the exact subgroup was not determined, although it d ... | 1990 | 2270226 |
| molecular cloning, expression and nucleotide sequence of the rcsa gene of erwinia amylovora, encoding a positive regulator of capsule expression: evidence for a family of related capsule activator proteins. | a gene encoding a positive activator of the expression of extracellular polysaccharide (eps) synthesis in the phytopathogen erwinia amylovora has been isolated from a genomic library in escherichia coli. the presence of the cloned gene in e. coli stimulated transcription of the genes encoding colanic acid biosynthesis and could complement rcsa mutations. introduction of the gene on a multicopy plasmid into er. amylovora caused a threefold increase in eps expression. the nucleotide sequence of th ... | 1990 | 2283503 |
| immuno gold staining (igs) and immuno gold silver staining (igss) for the identification of the plant pathogenic bacterium erwinia amylovora (burrill) winslow et al. | for the identification of the plant pathogenic bacterium erwinia amylovora, the immuno gold staining (igs) and immuno gold silver staining (igss) techniques are tested. the igs and igss methods are at least as sensitive an indirect immunofluorescence and require less primary antiserum. moreover they have the advantage that the preparations can be conserved permanently and unchanged. the preparation of the igs can be observed with transmitted light or--with considerable better result--using epipo ... | 1985 | 2416717 |
| a translational enhancer derived from tobacco mosaic virus is functionally equivalent to a shine-dalgarno sequence. | when present at the 5' end of mrnas, the untranslated leader sequence (omega) of tobacco mosaic virus rna significantly enhances translation in eukaryotes and prokaryotes. we have tested a deletion derivative of the omega sequence, omega delta 3, for its enhancing ability on gene constructs in which the ribosomal binding site was either present or deleted, in several gram-negative bacterial species including escherichia coli, agrobacterium tumefaciens, xanthomonas campestris pv. vitians, erwinia ... | 1989 | 2643095 |
| pulb113, an rp4::mini-mu plasmid, mediates chromosomal mobilization and r-prime formation in erwinia amylovora, erwinia chrysanthemi, and subspecies of erwinia carotovora. | the rp4::mini-mu plasmid pulb113, transferred from escherichia coli strain mxr, was stable and transfer proficient in erwinia amylovora strain ea303, e. carotovora subsp. atroseptica strain eca12, e. carotovora subsp. carotovora strain ecc193, and e. chrysanthemi strain ec183. the plasmid mobilized an array of erwinia sp. chromosomal markers (e. amylovora: his+,ilv+,rbs+,ser+,thr+;e. chrysanthemi:arg+,his+,ilv+,leu+; e. carotovora subsp. atroseptica: arg+,gua+,leu+,lys+,pur+,trp+; e. carotovora ... | 1985 | 2992373 |
| diversity of the phosphoenolpyruvate/glucose phosphotransferase system in the enterobacteriaceae. | the presence of the phosphoenolpyruvate glucose phosphotransferase entry routes was studied in 97 genospecies of enterobacteriaceae. phosphoenolpyruvate(pep)-dependent phosphorylation of alpha-methyl-d-glucoside and 2-deoxyglucose was evidenced in 72 species (group i organisms), suggesting the presence of both the iiglc (formerly ii-bglc/iiiglc) and iiman (formerly ii-b/ii-aman) entry routes. erwinia amylovora, budvicia aquatica and all species of leminorella and proteus (as defined by dna relat ... | 1987 | 3606872 |
| structure of the sidechain of lipopolysaccharide from erwinia amylovora t. | the sidechain of lipopolysaccharide from erwinia amylovora t was composed of d-fucose, d-galactose and d-glucose in equimolar proportions. using nmr spectroscopy, methylation analysis, mass spectrometry, smith degradation and optical rotation data, the repeat unit was shown to have the following most probable structure: (formula; see text) | 1987 | 3691526 |
| evolution of the lipoprotein gene in the enterobacteriaceae. cloning and dna sequence of the lpp gene from proteus mirabilis. | we cloned the lipoprotein gene from proteus mirabilis and determined its dna sequence. comparison with the lpp genes from escherichia coli, serratia marcescens, erwinia amylovora and morganella morganii revealed several unique features of the evolution of the lpp gene in the enterobacteriaceae and enabled us to establish phylogenetic relationships between these bacteria. | 1985 | 3903165 |
| bactericidal agents generated by the peroxidase-catalyzed oxidation of para-hydroquinones. | for the three gram-negative bacteria, pseudomonas fluorescens, escherichia coli, and erwinia amylovora, p-benzoquinone was the principal bactericidal agent formed in vitro during the oxidation of hydroquinone by horseradish peroxidase, whereas no toxicity could be associated with either phenolic or oxygen-free radicals. even the continuous generation of p-benzosemiquinone during the simultaneous reduction of p-benzoquinone by xanthine oxidase and reoxidation of hydroquinone by peroxidase was no ... | 1985 | 3932358 |
| ultrastructure of the cell wall of erwinia amylovora. | thin sectioned cells of erwinia amylovora revealed two electron-dense layers in their walls when fixed at 24 to 27 c and three when fixed at 4 c. | 1971 | 4105035 |
| ultrastructure of the cell wall and cytoplasmic membrane of gram-negative bacteria with different fixation techniques. | the ultrastructure of the cytoplasmic membrane and cell wall of two strains of escherichia coli, proteus morganii, p. vulgaris, acinetobacter anitratum, moraxella lacunata, erwinia amylovora, acinetobacter sp., and of a plant pathogen, unclassified gram-negative, fixed by the ryter-kellenberger procedure, was found to be significantly affected by the use or omission of the uranyl postfixation included in that procedure, and by the presence or absence of calcium in the oso(4) fixative. the omissi ... | 1973 | 4120570 |
| characteristics of erwinia amylovora bacteriophage and its possible role in the epidemology of fire blight. | | 1973 | 4125539 |
| association of virulence characteristics of erwinia amylovora with toxigenicity of its phage lysates to rabbit. | | 1973 | 4199439 |
| variation in the occurrence of extracellular diffusible antigens in temperature-induced variants of erwinia herbicola y46, and observations of their relationships with erwinia amylovora. | | 1974 | 4208906 |
| pyruvic acid metabolism and ethanol formation in erwinia amylovora. | | 1971 | 4400187 |
| the effect of temperature on the growth of the fireblight pathogen, erwinia amylovora. | | 1974 | 4436163 |
| transfer among erwinia spp. and other enterobacteria of antibiotic resistance carried on r factors. | antibiotic resistance carried on r factors was transferred by conjugation from escherichia coli b/r and shigella flexneri 1a to erwinia spp. tetracycline resistance (tetr) carried on r factor r100 drd-56 was transferred from e. coli b/r to strains of erwinia amylovora, e. aroideae, e. atroseptica, e. chrysanthemi, e. cytolytica, e. dissolvens, e. herbicola, e. nigrifluens, and e. nimipressuralis, but not to strains of erwinia carotovora, e. carnegieana, e. dieffenbachiae, e. oleraceae, and e. qu ... | 1972 | 4562410 |
| transmission of lac by the sex factor e in erwinia strains from human clinical sources. | lactose-utilizing (lac(+)) strains of erwinia spp. from human clinical material transfer lac by conjugation to plant strains of erwinia herbicola and erwinia amylovora, to other erwinia strains from human clinical sources, and also to escherichia coli, paracolobactrum arizonae, salmonella typhimurium, and shigella dysenteriae. the frequency of this transfer varies with the donor and recipient strains employed. the lac genes appear stable in these exconjugants, and they are not cured by acridine ... | 1973 | 4582635 |
| genetic transfer of episomic elements among erwinia species and other enterobacteria: f'lac+. | the episomic element f'lac(+) was transferred, probably by conjugation, from escherichia coli to lac(-) strains of erwinia herbicola, erwinia amylovora, and erwinia chrysanthemi (but not to several other erwinia spp. in preliminary trials). the lac genes in the exconjugants of the erwinia spp. showed varying degrees of stability depending on the strain (stable in e. herbicola strains y46 and y74 and e. amylovora strain ea178, but markedly unstable in e. chrysanthemi strain ec16). the lac genes a ... | 1972 | 4591473 |
| gene transmission among strains of erwinia amylovora. | stable donor strains of erwinia amylovora were obtained from strain ea178r(1) (harboring an escherichia coli f'lac) by selection for clones resistant to curing by acridine orange. these donor strains (ea178r(1)-99 and ea178r(1)-111) transfer chromosomal markers (arg, cys, gua, ilv, met, pro, ser, trp); the frequency of the appearance of recombinants prototrophic for cys, gua, met, ser, and trp is highest (> 10(-5)), followed by recombinants prototrophic for arg, ilv, and pro (10(-7) to 10(-5)). ... | 1973 | 4752937 |
| morphology and ultrastructure of normal rod-shaped and filamentous forms of erwinia amylovora. | filamentous cells of erwinia amylovora were usually 3 to 35 times longer than the normal rod-shaped ones, and only the former produced minicells. | 1970 | 4914085 |
| importance of pear-tissue injury to infection by erwinia amylovora and control with streptomycin. | | 1972 | 5034224 |
| parasitic interaction of bdellovibrio bacteriovorus with other bacteria. | starr, mortimer p. (university of california, davis), and nancy l. baigent. parasitic interaction of bdellovibrio bacteriovorus with other bacteria. j. bacteriol. 91:2006-2017. 1966.-the interactions of the predatory parasite, bdellovibrio bacteriovorus, with erwinia amylovora, pseudomonas tabaci, and p. phaseolicola were examined by means of phase-contrast and electron microscopy. attachment of the bdellovibrio to the host cell is apparently initially reversible; detachment occurs infrequently ... | 1966 | 5327913 |
| [serological diagnostic method without isolation of erwinia amylovora culture from a diseased plant]. | | 1967 | 5611662 |
| a disc electrophoretic comparison of protein patterns of erwinia amylovora with other bacteria, including associated yellow forms. | | 1968 | 5729094 |
| some observations on the physiology of erwinia herbicola and its possible implication as a factor antagonistic to erwinia amylovora in the "fire-blight" syndrome. | | 1969 | 5798523 |
| filamentous forms of erwinia amylovora. | | 1965 | 5827066 |
| numerical survey of some bacterial taxa. | focht, d. d. (iowa state university, ames), and w. r. lockhart. numerical survey of some bacterial taxa. j. bacteriol. 90:1314-1319. 1965.-a numerical analysis was made of 77 properties of each of 43 bacterial strains, representing 25 genera from 8 families in the orders eubacteriales and pseudomonadales. four major groups were found, related to one another at approximately the same level of similarity: (1) a large cluster containing the subgroups (1a) athiorhodaceae-spirillaceae, (1b) xanthomon ... | 1965 | 5848329 |
| comparison of the lipoprotein gene among the enterobacteriaceae. dna sequence of erwinia amylovora lipoprotein gene. | a dna sequence of 816 base pairs encompassing the entire erwinia amylovora lipoprotein gene was determined. sequence comparison between e. amylovora, escherichia coli, and serratia marcescens suggests that the structure of the lipoprotein has been highly conserved under the constraint of efficient gene expression selecting promoter structure, mrna secondary structure, and codon usage in addition to the polypeptide function. the sequence also suggests that the lpp gene of the three bacteria diver ... | 1981 | 6257705 |
| comparison of the lipoprotein gene among the enterobacteriaceae. dna sequence of morganella morganii lipoprotein gene and its expression in escherichia coli. | a dna sequence of 532 base pairs encompassing the entire morganella morganii lipoprotein gene (lpp) was determined. sequence comparisons of the m. morganii lpp gene with the lpp genes from escherichia coli, serratia marcescens, and erwinia amylovora reveal that the m. morganii lpp gene is more distantly related to the e. coli lpp gene than any of the other lpp genes examined. between the e. coli and m. morganii lpp genes, the following homologies were found: 44% in the promoter region (bases, -4 ... | 1983 | 6305973 |
| acceptance by erwinia spp. of r plasmid r68.45 and its ability to mobilize the chromosome of erwinia chrysanthemi. | r plasmid r68.45 was transferred in broth matings from escherichia coli to strains of erwinia amylovora, e. carotovora subsp. atroseptica, e. chrysanthemi, and e. herbicola (enterobacter agglomerans); the frequency of transfer ranged from 2 x 10(-8) to 5 x 10(-4) per input donor cell depending on the bacterial species. the drug resistance markers tet(+), amp(+), and kan(+) were stable in these erwinia species. transconjugants of erwinia spp., but not of the wild-type parent erwinia strains, acqu ... | 1980 | 6989797 |
| gluco-oligosaccharide production by a strain of erwinia amylovora. | when grown in sorbitol-asparagine-salts medium, cells of erwinia amylovora isolate t83 released a mixture of oligosaccharides and lipopolysaccharide in place of extracellular polysaccharide. the oligosaccharide fraction was usually readily separable from lipopolysaccharide by gel permeation chromatography, but some samples required disaggregation by preliminary treatment with edta. by 1h- and 13c-nmr spectroscopy, methylation analysis and mass spectrometry, the oligosaccharide fraction was shown ... | 1995 | 7476566 |
| expression of the stra-strb streptomycin resistance genes in pseudomonas syringae and xanthomonas campestris and characterization of is6100 in x. campestris. | expression of the stra-strb streptomycin resistance (smr) genes was examined in pseudomonas syringae pv. syringae and xanthomonas campestris pv. vesicatoria. the stra-strb genes in p. syringae and x. campestris were encoded on elements closely related to tn5393 from erwinia amylovora and designated tn5393a and tn5393b, respectively. the putative recombination site (res) and resolvase-repressor (tnpr) genes of tn5393 from e. amylovora, p syringae, and x. campestris were identical; however, is6100 ... | 1995 | 7487022 |
| genetics of galactose metabolism of erwinia amylovora and its influence on polysaccharide synthesis and virulence of the fire blight pathogen. | galactose metabolism mutants of erwinia amylovora were created by transposon insertions and characterized for their growth properties and interaction with plant tissue. the nucleotide sequence of the gale gene was determined. the gene, which encodes udp-galactose 4-epimerase, shows homology to the gale genes of escherichia coli, neisseria gonorrhoeae, rhizobium meliloti, and other gram-negative bacteria. cloned dna with the gale and with the galt and galk genes did not share borders, as judged b ... | 1994 | 7507102 |
| visualization of capsule formation by erwinia amylovora and assays to determine amylovoran synthesis. | exopolysaccharide (eps) synthesis by erwinia amylovora depends on environmental and genetic predispositions. to measure the amount of the acidic eps amylovoran synthesized by e. amylovora cell cultures, a turbidity assay using cetylpyridinium salt was developed. the eps produced by bacteria grown on solid media was additionally characterized by its water content. the amylovoran capsules were visualized in situ by staining with fluorescein isothiocyanate (fitc)-labelled lectin from abrus precator ... | 1994 | 7537077 |
| synthetic antimicrobial peptide design. | to guide the design of potential plant pathogen-resistance genes, synthetic variants of naturally occurring antimicrobial gene products were evaluated. five 20-amino acid (esf1, esf4, esf5, esf6, esf13), one 18-amino acid (esf12), and one 17-amino acid (esf17) amphipathic peptide sequences were designed, synthesized, and tested with in vitro bioassays. positive charges on the hydrophilic side of the peptide were shown to be essential for antifungal activity, yet the number of positive charges co ... | 1995 | 7579625 |
| proferrioxamine synthesis in erwinia amylovora in response to precursor or hydroxylysine feeding: metabolic profiling with liquid chromatography-electrospray mass spectrometry. | metabolic profiling by capillary liquid chromatography-electrospray mass spectrometry was used to monitor shifts in the proferrioxamine profiles of erwinia amylovora in response to externally supplied potential proferrioxamine precursors, selected stable-isotope-labeled precursors and atypical precursors. based on the qualitative and quantitative shifts in the proferrioxamine profiles, lysine and arginine are unambiguous, and agmatine, ornithine, diaminobutyric acid and the corresponding c3-5 di ... | 1995 | 7580052 |
| hrpl activates erwinia amylovora hrp gene transcription and is a member of the ecf subfamily of sigma factors. | hrpl of erwinia amylovora ea321 encodes a 21.7-kda regulatory protein, similar to members of the ecf (extra cytoplasmic functions) subfamily of eubacterial rna polymerase sigma factors. hrpl is a single-gene operon in complementation group vi of the e. amylovora hrp gene cluster. its product is required by ea321 to elicit the hypersensitive response (hr) and to cause disease. hrpl controls the expression of five independent hrp loci, including hrpn, which encodes harpin, a proteinaceous elicitor ... | 1995 | 7592386 |
| molecular analysis of the ams operon required for exopolysaccharide synthesis of erwinia amylovora. | a 16 kb transcript of the ams region, which is essential for biosynthesis of amylovoran, the acidic exopolysaccharide of erwinia amylovora, was detected by northern hybridization analysis. the positive regulator rcsa enhanced transcription of the large mrna from the ams operon. the nucleotide sequence of this area revealed 12 open reading frames (orfs), which are all transcribed in the same direction. five orfs corresponded to the previously mapped genes amsa to amse. sequence analysis of the in ... | 1995 | 7596293 |
| identification of the fire blight pathogen, erwinia amylovora, by pcr assays with chromosomal dna. | erwinia amylovora, the causative agent of fire blight, was identified independently from the common plasmid pea29 by three different pcr assays with chromosomal dna. pcr with two primers was performed with isolated dna and with whole cells, which were directly added to the assay mixture. the oligonucleotide primers were derived from the ams region, and the pcr product comprised the amsb gene, which is involved in exopolysaccharide synthesis. the amplified fragment of 1.6 kb was analyzed, and the ... | 1995 | 7618876 |
| [antibiotic resistance--an ambivalence of attitudes. as of now, the bacteria are in advantage]. | the value of the precious medical asset that antibiotics constitute is contimualby being eroded by the spread of resistance. for some time that bacterial world has been adapting itself to contend with the toxic assault of man-made poisons, antibiotics, by developing resistance in a very rapid process of evolutionary changes occurring before our very eyes. this evolutionary adaptation is an example of natural genetic engineering entailing an interchange between bacteria of genes conferring antibi ... | 1995 | 7674727 |
| purification and characterization of an extracellular levansucrase from pseudomonas syringae pv. phaseolicola. | levansucrase (ec 2.4.1.10), an exoenzyme of pseudomonas syringae pv. phaseolicola, was purified to homogeneity from the cell supernatant by chromatography on tmae-fraktogel and butyl-fraktogel. the enzyme has molecular masses of 45 kda under denaturing conditions and 68 kda during gel filtration of the native form. in isoelectric focusing, active bands appeared at ph 3.55 and 3.6. maximum sucrose cleaving activities were measured at ph 5.8 to 6.6 and 60 degrees c. the enzyme was highly tolerant ... | 1995 | 7751294 |
| molecular cloning and characterization of the extracellular sucrase gene (sacc) of zymomonas mobilis. | the zymomonas mobilis gene sacc that encodes the extracellular sucrase (protein b46) was cloned and expressed in escherichia coli. the gene was found to be present downstream to the already described levansucrase gene sacb in the cloned chromosomal fragment of z. mobilis. the expression product was different from sacb and exhibited sucrase but not levansucrase activity; therefore, sacc behaves like a true sucrase. expression of sacc in e. coli jm109 and xl1 was very low; overexpression was obser ... | 1995 | 7778976 |
| expression and identification of the stra-strb gene pair from streptomycin-resistant erwinia amylovora. | deletions in either of the genes in the stra-strb gene pair of erwinia amylovora plasmid pea34 resulted in a dramatic decrease in streptomycin resistance (smr), but smr was restored to high levels by complementation. when stra and strb were cloned separately on a laciq/ptac-based expression vector in escherichia coli, only the protein encoded by stra was produced. when a strong shine-dalgarno sequence was introduced and the start codon was located outside the double-stranded region of the stable ... | 1995 | 7828927 |
| profiling of basic amino acids and polyamines in microbial culture supernatants by electrospray mass spectrometry. | as part of our efforts to investigate the biosynthesis of proferrioxamines in erwinia amylovora, it was of interest to develop a methodology with which a large number of basic amino acids, di- and polyamines, and c- and n-hydroxy derivatives thereof could be monitored simultaneously. towards this end, the on-line coupling of electrospray mass spectrometry with ion chromatography or reversed-phase chromatography was explored. tandem mass spectrometry was found to be an excellent method for obtain ... | 1994 | 7841213 |
| metabolism of polyamines and basic amino acids in erwinia amylovora: application of liquid chromatography/electrospray mass spectrometry to proferrioxamine precursor feeding and inhibition studies. | erwinia amylovora, the etiological agent of fire blight, produces a family of proferrioxamine siderophores, which may be essential for the pathogen to establish itself in its hosts. if so, then control of fire blight may perhaps be possible via interference with proferrioxamine biosynthesis. proof of this hypothesis requires prior knowledge of the corresponding biosynthetic pathways in e. amylovora. as a first step towards understanding proferrioxamine biosynthesis, it was of interest to investi ... | 1994 | 7841214 |
| cloning, expression, and characterization of the lon gene of erwinia amylovora: evidence for a heat shock response. | the gene encoding the lon protease of erwinia amylovora has been cloned by complementation of an escherichia coli lon mutant. analysis of the determined nucleotide sequence of the lon gene revealed extensive homology to the nucleotide sequences of cloned lon genes from e. coli, myxococcus xanthus, and bacillus brevis. the predicted amino acid sequence of the e. amylovora lon protease was 94, 59, and 54% identical to the predicted amino acid sequences of the lon proteases of e. coli, m. xanthus, ... | 1995 | 7860603 |
| [the antagonistic activity of spore bacteria in relation to representatives of the genus erwinia]. | strains of 26 species of genus bacillus were examined for an antagonistic effect relative to erwiniosis agents: erwinia amylovora, erwinia carotovora, erwinia chryzanthemi, erwinia herbicola, erwinia rhapontici. the erwinia strain growth seized in the process of combined cultivation with microbes-antagonists. practically all the studied strains of bacteria of genus erwinia were sensitive to these or those bacillus cultures. a considerable number of erwinia strains studied were sensitive simultan ... | 1994 | 8087253 |
| hrpi of erwinia amylovora functions in secretion of harpin and is a member of a new protein family. | hrpi, a 78-kda protein, functions in the secretion of harpin, a proteinaceous elicitor of the hypersensitive response from erwinia amylovora. the predicted amino acid sequence of hrpi is remarkably similar to that of lcrd of yersinia species, the first member of a recently described protein family. other proteins of the family are mixa from shigella flexneri, inva from salmonella typhimurium, flha from caulobacter crescentus, hrpi from pseudomonas syringae pv. syringae, hrpo from pseudomonas sol ... | 1993 | 8253684 |
| nucleotide sequence and properties of the hrma locus associated with the pseudomonas syringae pv. syringae 61 hrp gene cluster. | the hrma locus, isolated from pseudomonas syringae pv. syringae 61, is essential for phenotypic expression of the p. s. pv. syringae 61 hrp cluster in escherichia coli strains and enables bacteria carrying the hrp/hrm gene cluster to elicit the hypersensitive response (hr) associated with plant disease resistance. the phenotype of p. s. pv syringae 61 hrma mutants (pathogenicity+, delayed hr) was distinct from that of hrp mutants. the locus was localized to a 3.6-kb bamh1-ecor1 fragment whose nu ... | 1993 | 8274770 |
| nucleotide sequence analysis of a transposon (tn5393) carrying streptomycin resistance genes in erwinia amylovora and other gram-negative bacteria. | a class ii tn3-type transposable element, designated tn5393 and located on plasmid pea34 from streptomycin-resistant strain ca11 of erwinia amylovora, was identified by its ability to move from pea34 to different sites in plasmids pgem3zf(+) and pucd800. nucleotide sequence analysis reveals that tn5393 consists of 6,705 bp with 81-bp terminal inverted repeats and generates 5-bp duplications of the target dna following insertion. tn5393 contains open reading frames that encode a putative transpos ... | 1993 | 8380801 |
| a gene cluster for amylovoran synthesis in erwinia amylovora: characterization and relationship to cps genes in erwinia stewartii. | a large ams gene cluster required for production of the acidic extracellular polysaccharide (eps) amylovoran by the fire blight pathogen erwinia amylovora was cloned. tn5 mutagenesis and gene replacement were used to construct chromosomal ams mutants. five complementation groups, essential for amylovoran synthesis and virulence in e. amylovora, were identified and designated ams a-e. the ams gene cluster is about 7 kb in size and functionally equivalent to the cps gene cluster involved in eps sy ... | 1993 | 8389975 |
| penicillin-binding proteins from erwinia amylovora: mutants lacking pbp2 are avirulent. | radiolabelled penicillin g was used to examine penicillin-binding proteins (pbps) from erwinia amylovora (ot1). this procedure identified seven pbps with molecular masses ranging from 22 to 83 kda. e. amylovora pbps were compared with those from escherichia coli (jm101) and from two spherical, avirulent tnphoa mutants derived from ot1. radiolabelled penicillin g bound to only six proteins from the spherical mutants which lacked a 69-kda pbp. the spherical mutants could be complemented by the clo ... | 1993 | 8407779 |
| erwinia chrysanthemi harpinech: an elicitor of the hypersensitive response that contributes to soft-rot pathogenesis. | mutants of the soft-rot pathogen erwinia chrysanthemi ec16 that are deficient in the production of the pectate lyase isozymes pelabce can elicit the hypersensitive response (hr) in tobacco leaves. the hrpnech gene was identified in a collection of cosmids carrying e. chrysanthemi hrp genes by its hybridization with the erwinia amylovora hrpnea gene. hrpnech appears to be in a monocistronic operon, and it encodes a predicted protein of 340 amino acids that is glycine-rich, lacking in cysteine, an ... | 1995 | 8589405 |
| erwinia amylovora secretes harpin via a type iii pathway and contains a homolog of yopn of yersinia spp. | type iii secretion functions in flagellar biosynthesis and in export of virulence factors from several animal pathogens, and for plant pathogens, it has been shown to be involved in the export of elicitors of the hypersensitive reaction. typified by the yop delivery system of yersinia spp., type iii secretion is sec independent and requires multiple components. sequence analysis of an 11.5-kb region of the hrp gene cluster of erwinia amylovora containing hrpi, a previously characterized type iii ... | 1996 | 8626302 |
| molecular characterization of the levansucrase gene from the endophytic sugarcane bacterium acetobacter diazotrophicus srt4. | the acetobacter diazotrophicus srt4 gene encoding levansucrase (ec 2.4.1.10) (isda) was isolated from a genomic library. the nucleotide sequence of a 2.3 kb dna fragment sufficient for complementation of a levansucrase-deficient mutant (obtained by ems treatment) was determined. the isda gene (1751 bp) coded for a polypeptide of molecular mass 64.9 kda with an isoelectric point of 5.2. the n-terminal amino acid sequence of the extracellular levansucrase indicated the presence of a precursor prot ... | 1996 | 8704949 |
| genetic transfer of amylovoran and stewartan synthesis between erwinia amylovora and erwinia stewartii. | dna fragments with ams genes of erwinia amylovora and cps genes of erwinia stewartii were transferred to exopolysaccharide (eps)-deficient mutants of the other species. the resulting epss were characterized by sensitivity to eps-dependent bacteriophages, staining with amylovoran-specific fluorescein-isothiocyanate-labelled lectin and chemical techniques, such as determination of the sugar composition and methylation analysis in order to distinguish between amylovoran and stewartan. degradation b ... | 1996 | 8704950 |
| desferrioxamine-dependent iron transport in erwinia amylovora cfbp1430: cloning of the gene encoding the ferrioxamine receptor foxr. | iron deprivation of erwinia amylovora cfbp1430, a species causing fire blight on pomoïdeae, was shown to induce the production of siderophores of the desferrioxamine (dfo) family and two outer membrane polypeptides with apparent molecular weight of about 70 and 80 kda, respectively. cyclic dfo e was characterized as the major metabolite. phage mudiipr13 insertional mutagenesis and screening on cas-agar medium yielded three dfo non-producing and one overproducing clones. these clones failed to gr ... | 1996 | 8744897 |
| identification of the promoter region for the colanic acid polysaccharide biosynthetic genes in escherichia coli k-12. | the colanic acid polysaccharide capsule biosynthetic genes (cps genes) are primarily clustered at one site located at about 45 min on the escherichia coli chromosome. the network of proteins involved in regulating the expression of these genes includes the two positive regulators rcsa and rcsb. this work describes the site of action of these two activator proteins and the promoter of the cps genes. it is likely that the cps genes are arranged in a single long operon that is at least 13.5 kb. the ... | 1996 | 8763957 |
| structure of amylovoran, the capsular exopolysaccharide from the fire blight pathogen erwinia amylovora. | the acidic exopolysaccharide (eps) of erwinia amylovora, amylovoran, was purified from culture supernatants of bacteria in minimal medium and cleaved chemically either by treatment with trifluoracetic acid or hydrofluoric acid, and enzymatically by digestion with depolymerase from e. amylovora phage phi-ealh. structural characterization of the resulting oligosaccharides was performed by a combination of mass spectrometric and nmr [one- and two-dimensional (1d and 2d)] spectroscopic techniques. a ... | 1996 | 8765060 |
| synthesis of fructans in tubers of transgenic starch-deficient potato plants does not result in an increased allocation of carbohydrates. | inhibition of starch biosynthesis in transgenic potato (solanum tuberosum l. cv. désirée) plants (by virtue of antisense inhibition of adp-glucose pyrophosphorylase) has recently been reported to influence tuber formation and drastically reduce dry matter content of tubers, indicating a reduction in sink strength (müller-röber et al. 1992, embo j 11: 1229-1238). transgenic tubers produced low levels of starch, but instead accumulated high levels of soluble sugars. we wanted to know whether these ... | 1996 | 8818293 |
| hrp gene-dependent induction of hin1: a plant gene activated rapidly by both harpins and the avrpto gene-mediated signal. | two classes of bacterial genes are involved in the elicitation of the plant hypersensitive response (hr) in resistant plants: hrp genes and avr genes. hrp genes have been shown to be involved in the production and secretion of a new class of bacterial virulence/avirulence proteins, including harpin of erwinia amylovora and harpinpss of pseudomonas syringae. the ability of avr genes in the elicitation of the hr/resistance is dependent on functional hrp genes. the relationships between harpins and ... | 1996 | 8893538 |
| characterization of the amsi gene product as a low molecular weight acid phosphatase controlling exopolysaccharide synthesis of erwinia amylovora. | the ams region, responsible for amylovoran synthesis of the fireblight pathogen erwinia amylovora, contains the gene amsi encoding a 144 amino acid protein with homology to mammalian low molecular weight acid phosphatases [bugert and geider (1995) mol. microbiol. 15, 917-9331. a dna fragment with amsi was cloned under the control of the lac promoter on a high copy number plasmid. the gene product of amsl is about 17 kda in a protein expression system and had the enzymatic activity of an acid pho ... | 1997 | 9001408 |
| characterization of the rcsb gene from erwinia amylovora and its influence on exoploysaccharide synthesis and virulence of the fire blight pathogen. | rcsb belongs to a family of positive regulators of exopolysaccharide synthesis in various enterobacteria. the rcsb gene of the fire blight pathogen erwinia amylovora was cloned by pcr amplification with consensus primers, and its role in exopolysaccharide (eps) synthesis was investigated. its overexpression from high-copy-number plasmids stimulated the synthesis of the acidic eps amylovoran and suppressed expression of the levan-forming enzyme levansucrase. inactivation of rcsb by site-directed ... | 1997 | 9023222 |
| the hrpa and hrpc operons of erwinia amylovora encode components of a type iii pathway that secretes harpin. | a 6.2-kb region of dna corresponding to complementation groups ii and iii of the erwinia amylovora hrp gene cluster was analyzed. transposon mutagenesis indicated that the two complementation groups are required for secretion of harpin, an elicitor of the hypersensitive reaction. the sequence of the region revealed 10 open reading frames in two putative transcription units: hrpa, hrpb, hrcj, hrpd, and hrpe in the hrpa operon (group iii) and hrpf, hrpg, hrcc, hrpt, and hrpv in the hrpc operon (gr ... | 1997 | 9045830 |
| the solution molecular weight and shape of the bacterial exopolysaccharides amylovoran and stewartan. | amylovoran, the acidic exopolysaccharide (eps) of erwinia amylovora, and stewartan, the capsular eps of e. stewartii, were characterized by analytical ultracentrifugation and by size exclusion chromatography connected to dual detection of light scattering and mass. the average molecular weights of amylovoran and stewartan were determined as 1.0 x 10(6) and 1.7 x 10(6) da, with polydispersity values (mw/m(n)) of 1.5 and 1.4, respectively. based on the sugar composition and their molecular weight, ... | 1997 | 9253645 |
| 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 |
| interaction of the regulator proteins rcsa and rcsb with the promoter of the operon for amylovoran biosynthesis in erwinia amylovora. | the rcsa and rcsb proteins of erwinia amylovora and escherichia coli were expressed in e. coli and purified. their dna-binding activity was examined using a 1-kb dna region containing the putative promoter of the ams operon of ew. amylovora, which is responsible for the biosynthesis of the exopolysaccharide amylovoran. mobility shift assays indicated specific binding of rcsa and rcsb to a region of 78 bp spanning nucleotide positions -578 to -501 relative to the translational start of the first ... | 1997 | 9341681 |
| measurement of ca2+ fluxes during elicitation of the oxidative burst in aequorin-transformed tobacco cells. | we have employed suspension cultured aequorin-transformed tobacco cells to examine the involvement of ca2+ in signal transduction of the oxidative burst. use of cultured cells for this purpose was validated by demonstrating that the cells responded to cold shock quantitatively and qualitatively similarly to the intact transgenic plants from which they were derived. stimulation of the oxidative burst in the cell suspension was achieved by administration of oligogalacturonic acid, mas-7 (a peptide ... | 1997 | 9353281 |
| differentiation of erwinia amylovora strains by pulsed-field gel electrophoresis. | erwinia amylovora strains, isolated from several host plants in various geographic regions during different years, were analyzed by pulsed-field gel electrophoresis (pfge) after digestion of the dna from lysed, agar-embedded cells with rare-cutting restriction enzymes. the banding patterns obtained with enzyme xbai digests revealed significant differences among strains from different areas. north american strains e9 and ea-rb, a rubus strain, were highly divergent from other e. amylovora strains ... | 1997 | 9361429 |
| a relative of the broad-host-range plasmid rsf1010 detected in erwinia amylovora. | streptomycin- and sulfonamide-resistant erwinia amylovora ca3r from california contained an 8.7-kb plasmid, pea8.7, with a sulii-stra-strb resistance region; furthermore, pcr, sequencing, hybridization, and restriction analyses showed that pea8.7 was closely related or identical to broad-host-range plasmid rsf1010. although rsf1010 has been found in a variety of bacteria, this is the first report of its presence in plant pathogenic bacteria. | 1997 | 9361446 |
| identification of a genetic locus essential for serotype b-specific antigen synthesis in actinobacillus actinomycetemcomitans. | a large gene cluster associated with the biosynthesis of the serotype-specific polysaccharide antigen (spa) of actinobacillus actinomycetemcomitans y4 (serotype b) was cloned and characterized. western blot analysis showed that escherichia coli dh5alpha, containing a plasmid carrying this cluster, produced a polysaccharide which reacted with a monoclonal antibody directed against the spa of a. actinomycetemcomitans y4. high-performance liquid chromatography analysis indicated that the polysaccha ... | 1998 | 9423846 |
| dspa, an essential pathogenicity factor of erwinia amylovora showing homology with avre of pseudomonas syringae, is secreted via the hrp secretion pathway in a dspb-dependent way. | in erwinia amylovora, the dsp region, required for pathogenicity on the host plant but not for hypersensitive elicitation on tobacco, is separated from the hrp region by 4 kb. the genetic analysis reported in this paper showed that this 4kb region is not required for pathogenicity on pear seedlings. the environmental conditions allowing expression of a dsp::lacz fusion were examined: expression was barely detected in rich medium at 30 degrees c, and the highest expression was observed in m9 gala ... | 1997 | 9426142 |
| genetics of sorbitol metabolism in erwinia amylovora and its influence on bacterial virulence. | a chromosomal dna fragment from erwinia amylovora was identified that complemented a deletion mutant in the gut(srl) operon of escherichia coli. the e. amylovora srl operon on the cloned fragment was localized by transposon mutagenesis. a dna fragment including the srl genes of e. amylovora was sequenced and found to contain six open reading frames (orfs). these orfs were highly homologous to genes of the gut operon of e. coli. no large gene was found that encoded a protein equivalent to guta of ... | 1997 | 9435786 |
| specific amino acid substitutions in the proline-rich motif of the rhizobium meliloti exop protein result in enhanced production of low-molecular-weight succinoglycan at the expense of high-molecular-weight succinoglycan. | the production of the acidic exopolysaccharide succinoglycan (eps i) by rhizobium meliloti exop* mutants expressing an exop protein lacking its c-terminal cytoplasmic domain and by mutants characterized by specific amino acid substitutions in the proline-rich motif (rx4px2px4spkx9ixgxmxgxg) located from positions 443 to 476 of the exop protein was analyzed. the absence of the c-terminal cytoplasmic exop domain (positions 484 to 786) and the substitution of both arginine443 by isoleucine443 and p ... | 1998 | 9440529 |
| homology and functional similarity of an hrp-linked pathogenicity locus, dspef, of erwinia amylovora and the avirulence locus avre of pseudomonas syringae pathovar tomato. | the "disease-specific" (dsp) region next to the hrp gene cluster of erwinia amylovora is required for pathogenicity but not for elicitation of the hypersensitive reaction. a 6.6-kb apparent operon, dspef, was found responsible for this phenotype. the operon contains genes dspe and dspf and is positively regulated by hrpl. a blast search revealed similarity in the dspe gene to a partial sequence of the avre locus of pseudomonas syringae pathovar tomato. the entire avre locus was sequenced. homolo ... | 1998 | 9448330 |
| oxidative burst and hypoosmotic stress in tobacco cell suspensions | oxidative burst constitutes an early response in plant defense reactions toward pathogens, but active oxygen production may also be induced by other stimuli. the oxidative response of suspension-cultured tobacco (nicotiana tabacum cv xanthi) cells to hypoosmotic and mechanical stresses was characterized. the oxidase involved in the hypoosmotic stress response showed similarities by its nadph dependence and its inhibition by iodonium diphenyl with the neutrophil nadph oxidase. activation of the o ... | 1998 | 9490766 |
| production of 1-kestose in transgenic yeast expressing a fructosyltransferase from aspergillus foetidus. | sucrose-inducible secretory sucrose:sucrose 1-fructosyltransferase (1-sst) from aspergillus foetidus has been purified and subjected to n-terminal amino acid sequence determination. the enzyme is extensively glycosylated, and the active form is probably represented by a dimer of identical subunits with an apparent molecular mass of 180 kda as judged from mobility in seminative acrylamide gels. the enzyme catalyzes fructosyl transfer from sucrose to sucrose producing glucose and 1-kestose. oligos ... | 1998 | 9495772 |
| erwinia amylovora secretes dspe, a pathogenicity factor and functional avre homolog, through the hrp (type iii secretion) pathway. | erwinia amylovora was shown to secrete dspe, a pathogenicity factor of 198 kda and a functional homolog of avre of pseudomonas syringae pv. tomato. dspe was identified among the supernatant proteins isolated from cultures grown in an hrp gene-inducing minimal medium by immunodetection with a dspe-specific antiserum. secretion required an intact hrp pathway. | 1998 | 9555912 |