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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Invasin is the primary invasive factor of Yersinia pseudotuberculosis that allows efficient internalization into eukaryotic cells. We investigated invasin expression and found that the inv gene is regulated in response to a variety of environmental signals, such as temperature, growth phase, nutrients, osmolarity and pH, and requires the product of rovA, a member of the SlyA/Hor transcriptional activator family. The rovA gene was found by a genetic complementation strategy that restores temperature regulation of an unexpressed inv-phoA fusion in Escherichia coli K-12. RovA plays a role in the invasion of Y. pseudotuberculosis into mammalian cells and mediates the regulation of invasin in response to all environmental signals analysed. Deletion analysis of the inv promoter region revealed a DNA segment extending 207 bp upstream of the transcriptional start site, which is required for maximal RovA-induced inv transcription. Gel retardation assays showed that RovA interacts preferentially with this promoter fragment and suggested two potential RovA binding sites. Studies with chromosomal gene fusions also demonstrated that rovA follows the same pattern of regulation as invasin, indicating that environmental control of inv expression is mainly mediated by the control of RovA synthesis. Furthermore, we showed that a rovA-lacZ fusion is only slightly expressed in a rovA mutant strain, indicating that a positive autoregulatory mechanism is also involved in rovA expression.
Mol Microbiol 2001 Sep
PMID:Environmental control of invasin expression in Yersinia pseudotuberculosis is mediated by regulation of RovA, a transcriptional activator of the SlyA/Hor family. 1158 Aug 32

Yersinia enterocolitica, Yersinia pseudotuberculosis, and Yersinia pestis deliver different Yop (Yersinia outer proteins) effector proteins into mammalian cells by a type III secretion mechanism. Recently, it was shown that Yersinia producing YopT leads to disruption of the actin cytoskeleton of HeLa cells (M. Iriarte and G. R. Cornelis, Mol. Microbiol. 29:915-929, 1998). To analyze the molecular mechanism of YopT, we cloned and expressed YopT as a glutathione S-transferase fusion protein. Recombinant YopT caused rounding up of embryonic bovine lung cells and redistribution of the actin cytoskeleton rapidly after microinjection. The Escherichia coli cytotoxic necrotizing factor (CNF1), which constitutively activates Rho proteins, was not able to inhibit or revert YopT-induced cell rounding. YopT caused release of RhoA from embryonic bovine lung membranes and released recombinant isoprenylated RhoA from artificial PE or PE/PIP2 vesicles. Incubation of lysate or cytosol with YopT caused inhibition of the RhoA-rhotekin interaction but led to increased RhoA-RhoGDI interaction. It is suggested that inhibition of the interaction between RhoA and effectors is the underlying mechanism of the YopT action on the cytoskeleton.
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PMID:Recombinant Yersinia YopT leads to uncoupling of RhoA-effector interaction. 1170 30

Efficient uptake of Yersinia pseudotuberculosis into cultured mammalian cells is the result of high-affinity binding of invasin to beta1 chain integrins. We demonstrate here that uptake requires Rac1 and Arp 2/3 function. Bacterial uptake was stimulated by GTPgammaS, but was inhibited in mammalian cells transfected with the interfering Rac1-N17 derivative. Rac1 was found to be activated in response to integrin engagement by invasin, whereas Rac1 and Arp 2/3 were found to be intensely localized around phagosomes bearing bacteria, indicating a specific role for Rac1 signalling from the nascent phagosome to downstream effectors. To determine whether the Arp 2/3 complex was a component of this proposed pathway, cells overproducing various derivatives of Scar1/WAVE1, an Arp 2/3-binding protein, were analysed. Sequestration of Arp 2/3 away from the phagocytic cup as a result of Scar1/WAVE1 overproduction dramatically inhibited uptake. To determine whether signalling from Rac1 to Arp 2/3 occurred via N-WASP, uptake was analysed in a cell line lacking expression of WASP and N-WASP. Uptake was unaffected by the absence of these proteins, indicating that beta1 integrin signalling from Rac1 to Arp 2/3 can occur in the absence of N-WASP function.
Mol Microbiol 2001 Nov
PMID:Efficient uptake of Yersinia pseudotuberculosis via integrin receptors involves a Rac1-Arp 2/3 pathway that bypasses N-WASP function. 1172 35

Pathogenic strains of Yersinia deploy a type III secretion system to inject the potent tyrosine phosphatase YopH into host cells, where it dephosphorylates focal adhesion-associated substrates. The amino-terminal, non-catalytic domain of YopH is bifunctional; it is essential for the secretion and binding of the specific chaperone SycH, but also targets the catalytic domain to substrates in the infected cell. We describe the 2.2 A resolution crystal structure of residues 1-129 of YopH from Yersinia pseudotuberculosis. The amino-terminal alpha-helix (2-17), comprising the secretion signal, and beta-strand (24-28) of one molecule exchange with another molecule to form a domain-swapped dimer. Nuclear magnetic resonance (NMR) and gel filtration experiments demonstrated that YopH(1-129) could exist as a monomer and/or a dimer in solution. The topology of the dimer and the dynamics of a monomeric form in solution observed by NMR imply that YopH has the propensity to unfold partially. The dimer is probably not important physiologically, but may mimic how SycH binds to the exposed non-polar surfaces of a partially unfolded YopH. Phosphopeptide-induced perturbations in NMR chemical shifts define a substrate-binding surface on YopH(1-129) that includes residues previously shown by mutagenesis to be essential for YopH function.
Mol Microbiol 2001 Nov
PMID:Structure of the type III secretion and substrate-binding domain of Yersinia YopH phosphatase. 1173 40

The enteropathogen Yersinia pseudotuberculosis is a model system used to study the molecular mechanisms by which Gram-negative pathogens secrete and subsequently translocate antihost effector proteins into target eukaryotic cells by a common type III secretion system (TTSS). In this process, YopD (Yersinia outer protein D) is essential to establish regulatory control of Yop synthesis and the ensuing translocation process. YopD function depends upon the non-secreted TTSS chaperone LcrH (low-calcium response H), which is required for presecretory stabilization of YopD. However, as a new role for TTSS chaperones in virulence gene regulation has been proposed recently, we undertook a detailed analysis of LcrH. A lcrH null mutant constitutively produced Yops, even when this strain was engineered to produce wild-type levels of YopD. Furthermore, the YopD-LcrH interaction was necessary to regain the negative regulation of virulence associated genes yops). This finding was used to investigate the biological significance of several LcrH mutants with varied YopD binding potential. Mutated LcrH alleles were introduced in trans into a lcrH null mutant to assess their impact on yop regulation and the subsequent translocation of YopE, a Rho-GTPase activating protein, across the plasma membrane of eukaryotic cells. Two mutants, LcrHK20E, E30G, I31V, M99V, D136G and LcrHE30G lost all regulatory control, even though YopD binding and secretion and the subsequent translocation of YopE was indistinguishable from wild type. Moreover, these regulatory deficient mutants showed a reduced ability to bind YscY in the two-hybrid assay. Collectively, these findings confirm that LcrH plays an active role in yop regulation that might be mediated via an interaction with the Ysc secretion apparatus. This chaperone-substrate interaction presents an innovative means to establish a regulatory hierarchy in Yersinia infections. It also raises the question as to whether or not LcrH is a true chaperone involved in stabilization and secretion of YopD or a regulatory protein responsible for co-ordinating synthesis of Yersinia virulence determinants. We suggest that LcrH can exhibit both of these activities.
Mol Microbiol 2001 Nov
PMID:The type III secretion chaperone LcrH co-operates with YopD to establish a negative, regulatory loop for control of Yop synthesis in Yersinia pseudotuberculosis. 1173 48

The authors present published data and their own findings on the relationship between Yersinia pestis and Y. pseudotuberculosis and on the origination of Y. pestis from Y. pseudotuberculosis. Study of microbiological and biochemical characteristics, external membrane protein spectra, and stability of chromosomal region of pigmentation brought the authors to a hypothesis that Y. pestis minor subspecies (ssp. caucasica, altaica, hissarica, ulegeica) which are characterized by selective virulence occupy an intermediate position between Y. pseudotuberculosis and basic species of Y. pestis.
Mol Gen Mikrobiol Virusol 2002
PMID:[Modern concepts on the relationship between the agents causing plague and pseudotuberculosis]. 1190 22

LcrQ is a regulatory protein unique to Yersinia. Previous study in Yersinia pseudotuberculosis and Yersinia enterocolitica prompted the model in which LcrQ negatively regulates the expression of a set of virulence proteins called Yops, and its secretion upon activation of the Yop secretion (Ysc) type III secretion system permits full induction of Yops expression. In this study, we tested the hypothesis that LcrQ's effects on Yops expression might be indirect. Excess LcrQ was found to exert an inhibitory effect specifically at the level of Yops secretion, independent of production, and a normal inner Ysc gate protein LcrG was required for this activity. However, overexpression of LcrQ did not prevent YopH secretion, suggesting that LcrQ's effects at the Ysc discriminate among the Yops. We tested this idea by determining the effects of deletion or overexpression of LcrQ, YopH and their common chaperone SycH on early Yop secretion through the Ysc. Together, our findings indicated that LcrQ is not a negative regulator directly, but it acts in partnership with SycH at the Ysc gate to control the entry of a set of Ysc secretion substrates. A hierarchy of YopH secretion before YopE appears to be imposed by SycH in conjunction with both LcrQ and YopH. LcrQ and SycH in addition influenced the deployment of LcrV, a component of the Yops delivery mechanism. Accordingly, LcrQ appears to be a central player in determining the substrate specificity of the Ysc.
Mol Microbiol 2002 Jan
PMID:LcrQ and SycH function together at the Ysc type III secretion system in Yersinia pestis to impose a hierarchy of secretion. 1198 18

Several Gram negative bacteria use a complex system called "type III secretion system" (TTSS) to engage their host. The archetype of TTSS is the plasmid-encoded "Yop virulon" shared by the three species of pathogenic Yersinia (Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica). A second TTSS, called Ysa (for Yersinia secretion apparatus) was recently described in Y. enterocolitica 8081, a strain from serotype O:8. In this study, we describe the ysa locus from A127/90, another strain of serotype O:8, and we extend the sequence to several new genes encoding Ysp proteins which are the substrates of this secretion system, and a putative chaperone SycB. According to the deduced protein sequences, the ysa system from A127/90 is identical to that of 8081. It is different from the chromosome-encoded TTSS of Y. pestis but is instead closely related to the Mxi-Spa TTSS of Shigella and to the SPI-1 encoded TTSS of Salmonella enterica. We further demonstrated that the ysa locus is only present in biotype IB strains of Y. enterocolitica. Including this new Ysa system, a phylogenetic analysis of the 26 known TTSSs was carried out, based on the sequence analysis of three conserved proteins. All the TTSSs fall into five different clusters. The phylogenetic tree of these TTSSs is completely different from the evolutionary tree based on 16S RNA, indicating that TTSSs have been distributed by horizontal transfer.
J Mol Evol 2002 Jul
PMID:Characterization of the ysa pathogenicity locus in the chromosome of Yersinia enterocolitica and phylogeny analysis of type III secretion systems. 1216 41

Urea uptake in eukaryotes and prokaryotes occurs via diffusion or active transport across the cell membrane. Facilitated diffusion of urea in both types of organisms requires a single-component channel. In bacteria, these transport systems allow rapid access of urease to its substrate, resulting in ammonia production, which is needed either for resistance to acidity or as a nitrogen source. In Yersinia pseudotuberculosis, a ureolytic enteropathogenic bacterium, a gene of unknown function (yut) located near the urease locus was found to encode a putative membrane protein with weak homology to single-component eukaryotic urea transporters. When expressed in Xenopus oocytes, Yut greatly increases cellular permeability to urea. Inactivation of yut in Y. pseudotuberculosis results in diminished apparent urease activity and reduced resistance to acidity in vitro when urea is present in the medium. In the mouse model, bacterial colonization of the intestine mucosa is delayed with the Yut-deficient mutant. Although structurally unrelated, Yut and the Helicobacter pylori UreI urea channel were shown to be functionally interchangeable in vitro and are sufficient to allow urea uptake in both bacteria, thereby confirming their function in the respective parent organisms. Homologues of Yut were found in other yersiniae, Actinobacillus pleuropneumoniae, Brucella melitensis, Pseudomonas aeruginosa and Staphylococcus aureus. The Y. pseudotuberculosis Yut protein is therefore the first member of a novel class of bacterial urea permeases related to eukaryotic transporters.
Mol Microbiol 2002 Aug
PMID:The Yersinia pseudotuberculosis Yut protein, a new type of urea transporter homologous to eukaryotic channels and functionally interchangeable in vitro with the Helicobacter pylori UreI protein. 1218 Sep 33

Virulence of pathogenic bacteria of the genus Yersinia requires the injection of six effector proteins into the cytoplasm of host cells. The amino-terminal domain of one of these effectors, the tyrosine phosphatase YopH, is essential for translocation of YopH, as well as for targeting it to phosphotyrosine-containing substrates of the type pYxxP. We report the high-resolution solution structure of the N-terminal domain (residues 1-129) from the Yersinia pseudotuberculosis YopH (YopH-NT) in complex with N-acetyl-DEpYDDPF-NH(2), a peptide derived from an in vivo protein substrate. In contrast to the domain-swapped dimer observed in a crystal structure of the same protein (Smith, C. L., Khandelwal, P., Keliikuli, K., Zuiderweg, E. R. P., and Saper, M. A. (2001) Mol. Microbiol. 42, 967-979), YopH-NT is monomeric in solution. The peptide binding site is located on a beta-hairpin that becomes the crossover point in the dimer structure. The binding site has several characteristics that are reminiscent of SH2 domains, which also bind to pYxxP sequences.
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PMID:Solution structure and phosphopeptide binding to the N-terminal domain of Yersinia YopH: comparison with a crystal structure. 1223 85


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