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Virulence Plasmid (virulence + plasmid)
Selected AbstractsShigella spp. and enteroinvasive Escherichia coli pathogenicity factorsFEMS MICROBIOLOGY LETTERS, Issue 1 2005Claude Parsot Abstract Bacteria of Shigella spp. (S. boydii, S. dysenteriae, S. flexneri and S. sonnei) and enteroinvasive Escherichia coli (EIEC) are responsible for shigellosis in humans, a disease characterized by the destruction of the colonic mucosa that is induced upon bacterial invasion. Shigella spp. and EIEC strains contain a virulence plasmid of ,220 kb that encodes determinants for entry into epithelial cells and dissemination from cell to cell. This review presents the current model on mechanisms of invasion of the colonic epithelium by these bacteria and focuses on their pathogenicity factors, particularly the virulence plasmid-encoded type III secretion system. [source] Thermoregulation of the Escherichia coli O157:H7 pO157 ecf operon and lipid A myristoyl transferase activity involves intrinsically curved DNAMOLECULAR MICROBIOLOGY, Issue 2 2004Jang W. Yoon Summary Escherichia coli O157:H7 survives in diverse environments from the ruminant gastrointestinal tract to cool nutrient-dilute water. We hypothesized that the gene regulation required for this flexibility includes intrinsically curved DNA that responds to environmental changes. Three intrinsically curved DNAs were cloned from the E. coli O157:H7 virulence plasmid (pO157), sequenced and designated Bent 1 through Bent 3 (BNT1, BNT2 and BNT3). Compared to BNT1 and BNT3, BNT2 had characteristics typical of intrinsically curved DNA including electrophoretic gel retardation at 4°C, six partially phased adenine:thymine tracts and transcriptional activation. BNT2::lacZ operon fusions showed that BNT2 activated transcription at 24°C compared to 37°C and was partially repressed by a bacterial nucleoid-associated protein H-NS. BNT2 regulated the E. coli attaching and effacing gene-positive conserved fragments 1,4 (ecf1,4) that are conserved in Shiga toxin-producing E. coli associated with human disease. Experimental analyses showed that ecf1,4 formed an operon. ecf1, 2 and 3 encoded putative proteins associated with bacterial surface polysaccharide biosynthesis and invasion and ecf4 complemented a chromosomal deletion of lpxM encoding lipid A myristoyl transferase. Mass spectrometric analysis of lipid A from ecf and lpxM single and double mutants showed that myristoylation was altered at lower temperature. [source] IpgD, a protein secreted by the type III secretion machinery of Shigella flexneri, is chaperoned by IpgE and implicated in entry focus formationMOLECULAR MICROBIOLOGY, Issue 1 2000Kirsten Niebuhr Invasion of epithelial cells by Shigella flexneri involves entry and intercellular dissemination. Entry of bacteria into non-phagocytic cells requires the IpaA,D proteins that are secreted by the Mxi,Spa type III secretion machinery. Type III secretion systems are found in several Gram-negative pathogens and serve to inject bacterial effector proteins directly into the cytoplasm of host cells. In this study, we have analysed the IpgD protein of S. flexneri, the gene of which is located on the virulence plasmid at the 5, end of the mxi,spa locus. We have shown that IpgD (i) is stored in the bacterial cytoplasm in association with a specific chaperone, IpgE; (ii) is secreted by the Mxi,Spa type III secretion system in amounts similar to those of the IpaA,D proteins; (iii) is associated with IpaA in the extracellular medium; and (iv) is involved in the modulation of the host cell response after contact of the bacterium with epithelial cells. This suggests that IpgD is an effector that might be injected into host cells to manipulate cellular processes during infection. [source] Cutaneous pyogranuloma in a cat caused by virulent Rhodococcus equi containing an 87 kb type I plasmidAUSTRALIAN VETERINARY JOURNAL, Issue 1-2 2007MR Farias A 2-year-old intact male domestic shorthaired cat presented with a chronic, nodular, ulcerated, cutaneous lesion on the right thoracic limb. Histological and cytological examination revealed a pyogranulomatous inflammation with basophilic organisms in the macrophages. A virulent form of Rhodococcus equi containing an 87 kb type I (VapA) virulence plasmid was identified from cultures of biopsy samples. This report describes the clinicopathological features, plasmid profile and virulence of this case of R equi infection. [source] Yersinia outer proteins: YopsCELLULAR MICROBIOLOGY, Issue 3 2008Jennifer E. Trosky Summary The pathogenic bacteria Yersinia spp. contain a virulence plasmid that encodes a type III secretion system and effectors. During infection, four of the effectors target the actin cytoskeleton, crippling the phagocytic machinery in the infected cell. The remaining two effectors dampen the innate immune response by targeting important signalling pathways. Although the biochemical activity for each of these effectors is known, the mechanisms involved in their ordered secretion and delivery remain elusive. [source] Novel domains of the prokaryotic two-component signal transduction systemsFEMS MICROBIOLOGY LETTERS, Issue 1 2001Michael Y. Galperin Abstract The archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver CheY-like domain and a DNA-binding domain. Sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as PAS, GAF, HAMP, GGDEF, EAL, and HD-GYP. All of these domains are widely represented in bacteria, including 19 copies of the GGDEF domain and 17 copies of the EAL domain encoded in the Escherichia coli genome. In contrast, these novel signaling domains are much less abundant in bacterial parasites and in archaea, with none at all found in some archaeal species. This skewed phyletic distribution suggests that the newly discovered complexity of signal transduction systems emerged early in the evolution of bacteria, with subsequent massive loss in parasites and some horizontal dissemination among archaea. Only a few proteins containing these domains have been studied experimentally, and their exact biochemical functions remain obscure; they may include transformations of novel signal molecules, such as the recently identified cyclic diguanylate. Recent experimental data provide the first direct evidence of the participation of these domains in signal transduction pathways, including regulation of virulence genes and extracellular enzyme production in the human pathogens Bordetella pertussis and Borrelia burgdorferi and the plant pathogen Xanthomonas campestris. Gene-neighborhood analysis of these new domains suggests their participation in a variety of processes, from mercury and phage resistance to maintenance of virulence plasmids. It appears that the real picture of the complexity of phosphorelay signal transduction in prokaryotes is only beginning to unfold. [source] Molecular and infection biology of the horse pathogen Rhodococcus equiFEMS MICROBIOLOGY REVIEWS, Issue 5 2009Kristine Von Bargen Abstract The soil actinomycete Rhodococcus equi is a pulmonary pathogen of young horses and AIDS patients. As a facultative intracellular bacterium, R. equi survives and multiplies in macrophages and establishes its specific niche inside the host cell. Recent research into chromosomal virulence factors and into the role of virulence plasmids in infection and host tropism has presented novel aspects of R. equi infection biology and pathogenicity. This review will focus on new findings in R. equi biology, the trafficking of R. equi -containing vacuoles inside host cells, factors involved in virulence and host resistance and on host,pathogen interaction on organismal and cellular levels. [source] | ||||||||||