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Query: UNIPROT:P06889 (Mol)
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The hrp gene cluster of Pseudomonas solanacearum GMI1000 strain encodes functions that are essential for pathogenicity on tomato and for the elicitation of the hypersensitive response on tobacco. In this study, we present the nucleotide sequence of one of the hrp genes (hrpB) located at the left-hand end of the cluster and we show that hrpB encodes a positive regulator controlling the expression of hrp genes. hrpB has a coding capacity for a 477-amino-acid polypeptide, which shows significant similarity to several prokaryotic transcriptional activators including the AraC protein of Escherichia coli, the XylS protein of Pseudomonas putida and the VirF protein of Yersinia enterocolitica. The predicted hrpB gene product belongs to a family of bacterial regulators different from the previously described HrpS protein of the hrp gene cluster of Pseudomonas syringae pv. phaseolicola. Genetic evidence demonstrates that the hrpB gene product acts as a positive regulator of the expression in minimal medium of all but one of the putative transcription units of the hrp gene cluster and also controls the expression of genes located outside this cluster. We also show in this paper that the transcription of hrpB is induced in minimal medium and is partly autoregulated.
Mol Microbiol 1992 Oct
PMID:Evidence that the hrpB gene encodes a positive regulator of pathogenicity genes from Pseudomonas solanacearum. 147 94

The Polymerase Chain Reaction (PCR) method was used to generate a vector-free digoxigenin-dUTP labelled probe that targets the Yersinia enterocolitica gene encoding the heat stable enterotoxin (yst). The probe was used in DNA-DNA colony hybridization to screen 113 strains of Y. enterocolitica and related species for the presence of the enterotoxin gene. In Y. enterocolitica, the probe clearly discriminated between pathogenic and non-pathogenic strains even those belonging to the same serotype. Of the other Yersinia species, only three strains of Y. kristensenii possessed DNA sequences homologous to the yst gene. The probe was further checked for its specificity in artificially inoculated fecal samples and could easily detect the target sequence of the yst gene. The digoxigenin-labelled probe proved to be a reliable epidemiological tool to discriminate between pathogenic and non-pathogenic strains in pure and mixed culture, thus offering the advantage of using a non-radioactive detection system in clinical laboratories with the possibility of reusing the same hybridization solution several times and obtaining results within a relatively short time.
Mol Cell Probes 1992 Apr
PMID:Differentiation between pathogenic and non-pathogenic Yersinia enterocolitica strains by colony hybridization with a PCR-mediated digoxigenin-dUTP-labelled probe. 151 45

Oligonucleotide probes directed to the inv and ail invasion genes of Yersinia species were used to analyse yersiniae and non-yersiniae isolates by colony hybridization. The INV-3 probe, targeted to the inv gene of Yersinia pseudotuberculosis, hybridized with all 48 HeLa cell-invasive Y. pseudotuberculosis isolates examined; the PF-13 probe, specific for the ail gene of Yersinia enterocolitica, identified all invasive strains (36 of 52) of Y. enterocolitica tested. Neither probe hybridized with non-yersinia isolates or other Yersinia species. Southern analyses of restriction enzyme-digested genomic DNA confirmed the specificity of both probes. INV-3 hybridized with a 4.5 kilobase (kb) Bam HI fragment known to carry the inv gene in Y. pseudotuberculosis. PF-13 was specific for a 1.2 kb Cla I-Ava I fragment in Y. enterocolitica that carried the ail locus. Reactivity with either probe correlated closely with the ability of Y. pseudotuberculosis and Y. enterocolitica isolates to invade HeLa cells.
Mol Cell Probes 1992 Aug
PMID:Identification of invasive Yersinia species using oligonucleotide probes. 152 99

Under iron-starvation, the highly pathogenic Yersinia synthesize several iron-regulated proteins including two high-molecular-weight polypeptides (HMWP1 and HMWP2). From the chromosome of Yersinia enterocolitica serovar O:8 (strain Ye 8081), the genes coding for the HMWP2 (irp2) and its promoter were cloned into plasmid pUC18 (pIR2) and used as a probe. We show here that the irp2 gene is present only in the highly pathogenic strains and that its promoter is iron-regulated in Escherichia coli. After introduction of the pIR2 plasmid into a fur mutant of E. coli, both the iron-starved and the iron-replete bacteria expressed the HMWP2. Repressibility of irp2 by iron was restored by introduction of a plasmid carrying the fur gene. These results demonstrate that the irp2 promoter is controlled by the Fur repressor in E. coli. Mutagenesis of the chromosomal irp2 gene of Yersinia pseudotuberculosis was obtained by homologous recombination with a 1 kb fragment of this gene cloned on the suicide plasmid pJM703.1. Inactivation of irp2 resulted in the non-expression of both HMWPs, while introduction of plasmid pIR2 into the mutant strain led to the synthesis of the HMWP2 only. Therefore, it is probable that the genes coding for the HMWPs constitute an operon where irp2 is upstream of irp1. When comparing the virulence of the wild-type strain and of its irp2 mutant derivative, we found that the 50% lethality (LD50) for mice of the mutant strain was increased, whatever the route of infection, but more markedly when injected parenterally. Accordingly, these data demonstrate that a mutation in the irp2 gene alters the pathogenicity of Y. pseudotuberculosis.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Microbiol 1992 Feb
PMID:Molecular cloning, iron-regulation and mutagenesis of the irp2 gene encoding HMWP2, a protein specific for the highly pathogenic Yersinia. 155 51

Upon incubation at 37 degrees C in the absence of Ca2+ ions, pathogenic yersiniae release high amounts of pYV plasmid-encoded proteins called Yops, involved in pathogenesis. Yersinia enterocolitica also express two outer membrane proteins, an adhesin called YadA and a lipoprotein called YlpA. The production of the Yops is co-ordinately regulated by a 20 kb region of the plasmid referred to as the 'Ca2+ dependence region' and containing at least four loci called virA, virB, virC, and virF. The 8.5 kb virC region, involved in the specific transport of the Yops, is a single operon containing 13 open reading frames called yscA to yscM. Gene virF encodes a key transcriptional activator of the yop, yadA and ylpA genes. It is only transcribed at 37 degrees C and its expression is modulated by a chromosome-encoded histone-like protein called YmoA. We show here that virF also controls the virC operon. By contrast, virF is not essential for the induction of virA and virB. The VirF protein binds specifically to yop promoters. In particular, it protects the region spanning nucleotides -64 to -34 of yopH. In order to analyse the role of temperature in the induction of the yop regulon, we constructed Y. enterocolitica strains expressing virF from the tac promoter. In spite of the fact that virF was transcribed at 25 degrees C, neither the Yops nor YadA were expressed at that temperature. This poor response to VirF at 25 degrees C was at least partially due to a weak and slow transcription of the genes controlled by virF. Surprisingly, when cloned on pACYC184, gene yadA was expressed even in absence of VirF, but remained thermodependent. Hence temperature and virF are both required for the induction of the yop regulon. Among other possible roles, temperature could modify the structure of either the activator itself or the yop promoter. The fact that VirF binds in vitro to yop promoters at 25 degrees C rules out the first hypothesis. In order to test the second hypothesis, we studied, in vivo, the activity of the yopH promoter in ymoA mutants. The yopH promoter became active in the absence of VirF, indicating that yop promoter activity depends upon chromatin structure. We conclude from these two observations that, in vivo, temperature is required to modify the DNA structure of the yop promoters in order to allow the action of the transcriptional activator.
Mol Microbiol 1992 Feb
PMID:Role of the transcriptional activator, VirF, and temperature in the expression of the pYV plasmid genes of Yersinia enterocolitica. 155 53

The eae (Escherichia coli attaching and effacing) gene from enteropathogenic Escherichia coli (EPEC) was previously shown to be essential for production of the 'attaching and effacing' histopathology characteristic of EPEC infections (Jerse et al., 1990). We have now cloned the eae gene from enterohaemorrhagic E. coli (EHEC) which, in addition to producing Shiga-like cytotoxins, also produces the attaching and effacing effect. The sequence homology between the EPEC and EHEC sequences was 86% and 83% at the nucleotide and amino acid levels, respectively. The predicted amino acid sequence of the EHEC eae gene shared 31% identity and 51% similarity with invasin of Yersinia pseudotuberculosis. Alignment of the EPEC and EHEC Eae proteins and the Y. pseudotuberculosis and Y. enterocolitica invasins shows striking regions of identity with the greatest divergence at the C-terminal end, the putative receptor-binding portion of invasin.
Mol Microbiol 1992 Feb
PMID:Cloning and characterization of the eae gene of enterohaemorrhagic Escherichia coli O157:H7. 155 54

The gene for the high-affinity outer membrane ferrioxamine receptor FoxA of Yersinia enterocolitica was cloned in Escherichia coli K-12. A foxA mutant of Yersinia could be complemented by the cloned DNA fragment. The FoxA encoding region was sequenced and an open reading frame encoding 710 amino acids, including a signal sequence of 26 amino acids, was deduced. The mature FoxA protein consisted of 684 amino acids and had a molecular mass of 75,768 Da. FoxA shared 33% amino acid sequence homology with FhuA, the ferrichrome receptor of Escherichia coli. Based on the homologies with FhuA and other TonB-dependent receptors a topological model of FoxA is presented.
Mol Microbiol 1992 May
PMID:Ferrioxamine uptake in Yersinia enterocolitica: characterization of the receptor protein FoxA. 164 Aug 32

The phenotypic properties conferred to Yersinia pseudotuberculosis cells by the genetical determinants of a 25Md fragment of the plasmid pVM82 coding for the modified cellular immune response in the infected organism. The fragment was shown to determine the conjugative properties of the plasmid, the resistance of bacterial cells to a number of hydrophobic agents and cellular ability to absorb the Congo red dye. The latter confirms the presence of additional structural components in the cell wall of the strain harbouring the plasmid pVM82. The increased resistance of the plasmid-containing strain to bactericidal effect of the blood plasma was demonstrated as compared with the resistance of the strains harbouring the p57 plasmid lacking the 25Md fragment or no plasmid at all.
Mol Gen Mikrobiol Virusol 1991 Dec
PMID:[Phenotypic features of a strain of Yersinia pseudotuberculosis with the pVM82 plasmid, detected at pseudotuberculosis outbreak foci]. 166 11

The sequence of 5'-region (16-296 n.) of 16S rRNA of plague agent (Yersinia pestis) was determined after sequencing of cloned cDNA fragments complementary to this region. When compared to the same region of 16S rRNA of Escherichia coli and Proteus vulgaris this region revealed 91.8% and 87.2% of homology, respectively. The sequences specific for Y. pestis 16S rRNA were localized and their secondary structure position was discussed.
Mol Biol (Mosk)
PMID:[Primary structure of the 5'-region of Yersinia pestis 16S rRNA]. 169 55

Virulent Yersinia species possess a common plasmid that encodes essential virulence determinants (Yops) which are regulated by the extracellular stimuli Ca2+ and temperature. The V antigen operon was recently shown to be involved in the Ca2(+)-regulated negative pathway (A. Forsberg and H. Wolf-Watz, Mol. Microbiol. 2:121-133, 1988). We show here that the V antigen-containing operon of Yersinia pseudotuberculosis is a polycistronic operon having the gene order lcrGVH-yopBD. DNA sequencing analysis of lcrGVH revealed a high homology to the corresponding genes of Yersinia pestis. LcrG was conserved and LcrH showed only one amino acid difference, while LcrV showed only 96.6% identity. The amino acid substitutions of LcrV occurred in the central domain of the protein, while the two ends of the protein were conserved. Northern (RNA) blotting experiments showed that the operon is regulated at the transcriptional level by the extracellular stimuli temperature and calcium. One 4.6-kb transcriptional product of the operon was identified. This mRNA is rapidly processed at its 5' end, resulting in different mRNA species of variable stability. By genetic analysis, the lcrV and lcrH gene products were found to be regulatory proteins having important roles in the Ca2(+)-controlled regulation of Yop expression. The activity of LcrH is modulated by a gene product of the operon that inhibits the negative action of LcrH on yop transcription in the absence of Ca2+.
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PMID:Analysis of the V antigen lcrGVH-yopBD operon of Yersinia pseudotuberculosis: evidence for a regulatory role of LcrH and LcrV. 170 41


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