Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The high-temperature requirement (HtrA) family of stress response proteins are induced by different environmental stress conditions in a variety of bacteria and have been shown to contribute to the pathogenicity of some of these species. In this study, the htrA gene from Yersinia enterocolitica O:8 was amplified, cloned, and sequenced. Analysis of the deduced amino acid sequence predicted that the putative HtrA homolog contains a serine protease active site and a catalytic triad characteristic of trypsin-like serine proteases, structural features characteristic of previously described HtrA proteins. In order to evaluate the biological functions of Y. enterocolitica HtrA, an isogenic mutant was constructed by a reverse-genetics PCR-based approach. Characterization of the mutant provided evidence supporting a stress response function for the Y. enterocolitica htrA gene product. In contrast to the parent strain, the mutant showed increased sensitivity to killing by H2O2, O2- and temperature stress (50 degrees C). The mutant was avirulent in the murine yersiniosis injection model and offered partial protection to mice challenged with the parent strain. Further studies with the Y. enterocolitica htrA mutant should increase our knowledge of the host-pathogen interactions which occur during Yersinia infections.
...
PMID:Construction and characterization of a Yersinia enterocolitica O:8 high-temperature requirement (htrA) isogenic mutant. 867 11

A novel 9 kD protein inhibitor of trypsin and related proteinases was purified from culture filtrate of Yersinia pseudotuberculosis by ultrafiltration, affinity chromatography, and gel filtration. The protein is stable at pH from 1 to 9. The inhibitor activity dramatically decreases at temperature above 37 degrees C. The purified inhibitor significantly suppresses activities of an endogenous trypsin-related proteinase and trypsin but does not affect chymotrypsin, pepsin, and papain. One molecule of yersinia inhibitor binds two molecules of endogenous trypsin-related proteinase and about one trypsin molecule. The Ki for yersinia proteinase is 1.7.10(-7) and Ki for trypsin is 2.4.10(-7). Amino acid composition of the inhibitor is characterized by the presence of beta-aminobutyric acid and ornithine and relatively high contents of alanine and arginine whereas cysteine, histidine, and proline are absent.
...
PMID:[Trypsin and microbial serine proteinase inhibitors isolated from Yersinia pseudotuberculosis]. 901 Dec 35

Invasive strains of Salmonella spp. cause both systemic and localized infections in humans. The ability to resist infection and some aspects of the tissue pathology associated with the presence of Salmonella in the gastrointestinal tract have been shown to be mediated in part by the induction of tumor necrosis factor alpha (TNF-alpha), a proinflammatory cytokine produced by activated macrophages and lymphocytes. Recent reports indicate that TNF-alpha is involved in the induction of human immunodeficiency virus replication by Salmonella in the latently infected human promonocytic cell line U1. In the present study, we investigated the effects of Salmonella on TNF-alpha production in U1 cells and a related cell line, U38. Unlike Escherichia coli or Yersinia enterocolitica, salmonellae rapidly induce TNF-alpha expression in these cells through a released factor(s). Time course experiments show that the kinetics of TNF-alpha production by U38 cells stimulated with Salmonella conditioned medium closely resemble those observed in response to live Salmonella. The observation that TNF-alpha levels are elevated by 60 min after exposure to either bacteria or their conditioned medium suggests that the soluble inducer is continuously released or shed by the bacteria and that the signal acts rapidly to increase TNF-alpha production. Furthermore, the ability to produce the TNF-alpha inducer is shared by at least four Salmonella serotypes and does not correlate with the abilities to invade and to survive within phagocytes. Treatment of active conditioned medium with trypsin, but not low pH, high temperature, or urea, significantly inhibits its TNF-alpha-inducing effect on U38 cells, a finding which points to a polypeptide product of Salmonella as the mediator of TNF-alpha production. Gel filtration chromatography of Salmonella conditioned medium reveals two peaks of activity, consistent with molecular masses of approximately 150 and 110 kDa.
...
PMID:Salmonellae activate tumor necrosis factor alpha production in a human promonocytic cell line via a released polypeptide. 935 43

Yersinia pestis expresses a set of secreted proteins called Yops and the bifunctional LcrV, which has both regulatory and antihost functions. Yops and LcrV expression and the activity of the type III mechanism for their secretion are coordinately regulated by environmental signals such as Ca2+ concentration and eukaryotic cell contact. In vitro, Yops and LcrV are secreted into the culture medium in the absence of Ca2+ as part of the low-Ca2+ response (LCR). The LCR is induced in a tissue culture model by contact with eukaryotic cells that results in Yop translocation into cells and subsequent cytotoxicity. The secretion mechanism is believed to indirectly regulate expression of lcrV and yop operons by controlling the intracellular concentration of a secreted negative regulator. LcrG, a secretion-regulatory protein, is thought to block secretion of Yops and LcrV, possibly at the inner face of the inner membrane. A recent model proposes that when the LCR is induced, the increased expression of LcrV yields an excess of LcrV relative to LcrG, and this is sufficient for LcrV to bind LcrG and unblock secretion. To test this LcrG titration model, LcrG and LcrV were expressed alone or together in a newly constructed lcrG deletion strain, a delta lcrG2 mutant, of Y. pestis that produces low levels of LcrV and constitutively expresses and secretes Yops. Overexpression of LcrG in this mutant background was able to block secretion and depress expression of Yops in the presence of Ca2+ and to dramatically decrease Yop expression and secretion in growth medium lacking Ca2+. Overexpression of both LcrG and LcrV in the delta lcrG2 strain restored wild-type levels of Yop expression and Ca2+ control of Yop secretion. Surprisingly, when HeLa cells were infected with the delta lcrG2 strain, no cytotoxicity was apparent and translocation of Yops was abolished. This correlated with an altered distribution of YopB as measured by accessibility to trypsin. These effects were not due to the absence of LcrG, because they were alleviated by restoration of LcrV expression and secretion alone. LcrV itself was found to enter HeLa cells in a nonpolarized manner. These studies supported the LcrG titration model of LcrV's regulatory effect at the level of Yop secretion and revealed a further role of LcrV in the deployment of YopB, which in turn is essential for the vectorial translocation of Yops into eukaryotic cells.
...
PMID:The V antigen of Yersinia pestis regulates Yop vectorial targeting as well as Yop secretion through effects on YopB and LcrG. 964 96

The YopM virulence protein of Yersinia pestis has been described as binding human alpha-thrombin and inhibiting thrombin-induced platelet aggregation in vitro. However, recent studies have shown that a YopM-CyaA fusion protein could be targeted vectorially into eukaryotic cells through the Yersinia type III secretion system. In this study, our objective was to characterize YopM's fate in more detail. We followed YopM in the culture medium and inside infected HeLa cells. We confirmed that the native YopM is targeted into HeLa cells, where it is insensitive to exogenous trypsin. The bacteria must be surface located to target YopM, and YopB and YopD are necessary, whereas the LcrE protein (called also YopN) makes this process more efficient. Immunofluorescence localization revealed that YopM, in contrast to YopE, is not only targeted to the cytoplasm but also trafficks to the cell's nucleus by means of a vesicle-associated pathway that is strongly inhibited by brefeldin A, perturbed by monensin or bafilomycin A1 and dependent upon microtubules (decreased by colchicine and nocodazole). These findings revealed a novel interaction of Yersinia pestis with its eukaryotic host.
...
PMID:Targeting of the Yersinia pestis YopM protein into HeLa cells and intracellular trafficking to the nucleus. 998 81

The periplasmic molecular chaperone Caf1M of Yersinia pestis is a typical representative of a subfamily of specific chaperones involved in assembly of surface adhesins with a very simple structure. One characteristic feature of this Caf1M-like subfamily is possession of an extended, variable sequence (termed FGL) between the F1 and subunit binding G1 beta-strands. In contrast, FGS subfamily members, characterized by PapD, have a short F1-G1 loop and are involved in assembly of complex pili. To elucidate the structural and functional significance of the FGL sequence, a mutant Caf1M molecule (dCaf1M), in which the 27 amino acid residues between the F1 and G1 beta-strands had been deleted, was constructed. Expression of the mutated caf1M in Escherichia coli resulted in accumulation of high levels of dCaf1M. The far-UV circular dichroism spectra of the mutant and wild-type proteins were indistinguishable and exhibited practically the same temperature and pH dependencies. Thus, the FGL sequence of Caf1M clearly does not contribute significantly to the stability of the protein conformation. Preferential cleavage of Caf1M by trypsin at Lys-119 confirmed surface exposure of this part of the FGL sequence in the isolated chaperone and periplasmic chaperone-subunit complex. There was no evidence of surface-localized Caf1 subunit in the presence of the Caf1A outer membrane protein and dCaf1M. In contrast to Caf1M, dCaf1M was not able to form a stable complex with Caf1 nor could it protect the subunit from proteolytic degradation in vivo. This demonstration that the FGL sequence is required for stable chaperone-subunit interaction, but not for folding of a stable chaperone, provides a sound basis for future detailed molecular analyses of the FGL subfamily of chaperones.
...
PMID:Structural and functional significance of the FGL sequence of the periplasmic chaperone Caf1M of Yersinia pestis. 1019 4

Diffusely adhering Escherichia coli (DAEC) strains have been implicated in epidemiological studies as a cause of diarrhoea in children. However, the molecular interactions of these pathogens with target cells have remained largely obscure. We found that some DAEC strains contain homologues of the locus of enterocyte effacement (LEE) pathogenicity island and secrete EspA, EspB and EspD proteins necessary for the formation of the attaching and effacing (A/E) lesions. To characterize the function of the EspD protein further, we cloned and sequenced the espD genes of two DA-EPEC strains and compared their deduced amino-acid sequences with known EspD sequences. A pattern of two conserved transmembrane regions and one conserved coiled-coil region is predicted in EspD and also in the type III system secreted proteins YopB, PopB, IpaB and SipB of Yersinia, Pseudomonas, Shigella and Salmonella respectively. The EspD protein is inserted into a trypsin-sensitive location in the HeLa cell membrane at sites of bacterial contact, but is not translocated into the cytoplasm. Secretion of EspD increases upon contact with host cells. We propose that the membrane-located EspD protein is part of the translocation apparatus for Esp proteins into the target host cell performing functions similar to YopB in Yersinia.
...
PMID:Insertion of EspD into epithelial target cell membranes by infecting enteropathogenic Escherichia coli. 1020 43

A trypsin-like proteinase (YPTP) and its endogenous inhibitor (ITYP) were isolated from the culture filtrate of the pathogenic bacterium Yersinia pseudotuberculosis, and their biological activities were studied. YPTP was found to be highly toxic for random-bred white mice. Under in vitro conditions the proteolytic enzyme destroyed protective proteins of the immune system of the animals--IgG, IgA, and proteins of the complement system (CIq, C3, and C5)--and, consequently, was a pathogenetic factor in yersinioses. The inhibitor ITYP was shown to manifest antibacterial activity against virulent forms of Yersinia pseudotuberculosis, Escherichia coli, and Salmonella typhimurium. The ITYP preparation was harmless and nontoxic.
...
PMID:Trypsin-like proteinase and its endogenous inhibitor from Yersinia pseudotuberculosis. Biological activity. 1052 13

A high molecular weight immunoglobulin-binding protein localized on the surface of bacterial cells has been isolated from the protein fraction of the outer membrane of Yersinia pseudotuberculosis, and its properties are described. The immunoglobulin-binding protein is a trypsin-resistant and temperature-sensitive beta-structured protein. As shown by MALDI-TOF mass spectrometry, after heating at 100 degrees C the molecular weight of the protein constituted 37.5 kD. The native protein is capable of interacting with human and rabbit IgG but looses the ability to bind the immunoglobulins after the temperature denaturation. The immunoglobulin-binding protein binds to the Fc-fragments of the immunoglobulins and binding depends on the presence of calcium ions.
...
PMID:Isolation and characterization of the immunoglobulin-binding protein from Yersinia pseudotuberculosis. 1238 24

Recently, it was shown that Yersinia outer protein T (YopT) belongs to a new family of cysteine proteases containing invariant C, H, and D residues that are crucial for its activity. YopT cleaves RhoA, Rac, and Cdc42 at their C termini, thereby releasing them from the membrane. Moreover, YopT inhibits the Rho-rhotekin and Rho-guanine nucleotide dissociation inhibitor interactions. To characterize the active domain of YopT, we constructed N- and C-terminal truncations and expressed them as glutathione S-transferase fusion proteins in Escherichia coli. The toxin fragments were tested for stability by trypsin digestion. The activity of the proteins was studied by membrane release assay, rhotekin pulldown experiments, and microinjection. Whereas deletion of the first 74 N-terminal amino acids did not influence the activity of YopT, deletion of 8 amino acids from the C terminus led to complete loss of activity. N-terminal deletion of 100 amino acids led to an inactive protein, although it still contained the amino acids C139, H258, and D274, which are essential for catalysis. Loss of activity of the N-terminal deletions corresponded to the block of interaction with RhoA, indicating that residues 75 to 100 of YopT are essential for binding to the GTPase. By contrast, when up to 15 amino acids of the C terminus were deleted, the protein had no activity but was still able to interact with RhoA, suggesting a role for the C terminus in the enzyme activity of YopT.
...
PMID:The C terminus of YopT is crucial for activity and the N terminus is crucial for substrate binding. 1287 42


<< Previous 1 2 3 4 Next >>

---