共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
Nick Quade Chriselle Mendonca Katharina Herbst Ann Kathrin Heroven Christiane Ritter Dirk W. Heinz Petra Dersch 《The Journal of biological chemistry》2012,287(43):35796-35803
Pathogens often rely on thermosensing to adjust virulence gene expression. In yersiniae, important virulence-associated traits are under the control of the master regulator RovA, which uses a built-in thermosensor to control its activity. Thermal upshifts encountered upon host entry induce conformational changes in the RovA dimer that attenuate DNA binding and render the protein more susceptible to proteolysis. Here, we report the crystal structure of RovA in the free and DNA-bound forms and provide evidence that thermo-induced loss of RovA activity is promoted mainly by a thermosensing loop in the dimerization domain and residues in the adjacent C-terminal helix. These determinants allow partial unfolding of the regulator upon an upshift to 37 °C. This structural distortion is transmitted to the flexible DNA-binding domain of RovA. RovA contacts mainly the DNA backbone in a low-affinity binding mode, which allows the immediate release of RovA from its operator sites. We also show that SlyA, a close homolog of RovA from Salmonella with a very similar structure, is not a thermosensor and remains active and stable at 37 °C. Strikingly, changes in only three amino acids, reflecting evolutionary replacements in SlyA, result in a complete loss of the thermosensing properties of RovA and prevent degradation. In conclusion, only minor alterations can transform a thermotolerant regulator into a thermosensor that allows adjustment of virulence and fitness determinants to their thermal environment. 相似文献
8.
9.
10.
11.
A sublethal concentration of copper (0.75 mg/liter) caused substantial injury (87 to 95%) of Yersinia enterocolitica serotype O:8 cells in 72 h at 4 degrees C without producing extensive cell death. Copper-injured cells had a higher 50% lethal dose in mice (2,700 CFU) than uninjured cells (150 CFU). This reduced virulence correlated with more rapid clearance of the injured cells from the blood of mice after intravenous inoculation. A possible role of the liver in this process was shown by significant cell accumulation in mouse livers when copper-injured Y. enterocolitica cells were administered, compared with uninjured bacteria. In vitro studies with isolated mouse liver membranes showed higher titers of aggregation with copper-injured cells than control cells. The in vitro aggregation reaction and blood clearance activity in vivo were abolished by sugars that are known to interact with a hepatic lectin. Our data suggest that copper-induced injury reduces the virulence of Y. enterocolitica and that the liver may be involved in nonimmune rapid clearance of the injured cells, probably by interaction with a hepatic lectin(s). 相似文献
12.
13.
PCR detection of virulence genes in Yersinia enterocolitica and Yersinia pseudotuberculosis and investigation of virulence gene distribution 总被引:6,自引:0,他引:6
Thoerner P Bin Kingombe CI Bögli-Stuber K Bissig-Choisat B Wassenaar TM Frey J Jemmi T 《Applied and environmental microbiology》2003,69(3):1810-1816
PCR-based assays were developed for the detection of plasmid- and chromosome-borne virulence genes in Yersinia enterocolitica and Yersinia pseudotuberculosis, to investigate the distribution of these genes in isolates from various sources. The results of PCR genotyping, based on 5 virulence-associated genes of 140 strains of Y. enterocolitica, were compared to phenotypic tests, such as biotyping and serotyping, and to virulence plasmid-associated properties such as calcium-dependent growth at 37 degrees C and Congo red uptake. The specificity of the PCR results was validated by hybridization. Genotyping data correlated well with biotype data, and most biotypes resulted in (nearly) homogeneous genotypes for the chromosomal virulence genes (ystA, ystB, and ail); however, plasmid-borne genes (yadA and virF) were detected with variable efficiency, due to heterogeneity within the bacterial population for the presence of the virulence plasmid. Of the virulence genes, only ystB was present in biotype 1A; however, within this biotype, pathogenic and apathogenic isolates could not be distinguished based on the detection of virulence genes. Forty Y. pseudotuberculosis isolates were tested by PCR for the presence of inv, yadA, and lcrF. All isolates were inv positive, and 88% of the isolates contained the virulence plasmid genes yadA and lcrF. In conclusion, this study shows that genotyping of Yersinia spp., based on both chromosome- and plasmid-borne virulence genes, is feasible and informative and can provide a rapid and reliable genotypic characterization of field isolates. 相似文献
14.
A sublethal concentration of copper (0.75 mg/liter) caused substantial injury (87 to 95%) of Yersinia enterocolitica serotype O:8 cells in 72 h at 4 degrees C without producing extensive cell death. Copper-injured cells had a higher 50% lethal dose in mice (2,700 CFU) than uninjured cells (150 CFU). This reduced virulence correlated with more rapid clearance of the injured cells from the blood of mice after intravenous inoculation. A possible role of the liver in this process was shown by significant cell accumulation in mouse livers when copper-injured Y. enterocolitica cells were administered, compared with uninjured bacteria. In vitro studies with isolated mouse liver membranes showed higher titers of aggregation with copper-injured cells than control cells. The in vitro aggregation reaction and blood clearance activity in vivo were abolished by sugars that are known to interact with a hepatic lectin. Our data suggest that copper-induced injury reduces the virulence of Y. enterocolitica and that the liver may be involved in nonimmune rapid clearance of the injured cells, probably by interaction with a hepatic lectin(s). 相似文献
15.
16.
Chromy BA Choi MW Murphy GA Gonzales AD Corzett CH Chang BC Fitch JP McCutchen-Maloney SL 《Journal of bacteriology》2005,187(23):8172-8180
The Yersinia pestis proteome was studied as a function of temperature and calcium by two-dimensional differential gel electrophoresis. Over 4,100 individual protein spots were detected, of which hundreds were differentially expressed. A total of 43 differentially expressed protein spots, representing 24 unique proteins, were identified by mass spectrometry. Differences in expression were observed for several virulence-associated factors, including catalase-peroxidase (KatY), murine toxin (Ymt), plasminogen activator (Pla), and F1 capsule antigen (Caf1), as well as several putative virulence factors and membrane-bound and metabolic proteins. Differentially expressed proteins not previously reported to contribute to virulence are candidates for more detailed mechanistic studies, representing potential new virulence determinants. 相似文献
17.
18.
19.
Study of the cultivation properties of 82 enterobacterial strains has revealed that the colonies of virulent Y. enterocolitica (serovars O3, O9) and Y. pseudotuberculosis (serovar I) are temperature-sensitive. This sign, closely connected with the presence and expression of the virulence plasmid with a molecular weight of 44-48 MD, is not characteristic of other strains. Virulent Yersinia grown in nutrient agar for 48 hours at 37 degrees C form colonies which are smaller in diameter than those formed during cultivation at 26 degrees C (with the significance of differences t greater than or equal to 4), their diameter at 37 degrees C not exceeding 1.0 mm. The test for the determination of the temperature-sensitive morphology of Yersinia colonies, along with the tests for other virulence markers, is probably suitable for the detection of the causative agents of yersiniosis or pseudotuberculosis. 相似文献
20.
Maria Dimou Anastasia Venieraki Panagiotis Katinakis 《World journal of microbiology & biotechnology》2017,33(9):164
Cyclophilins belong to the superfamily of peptidyl-prolyl cis/trans isomerases (PPIases, EC: 5.2.1.8), the enzymes that catalyze the cis/trans isomerization of peptidyl-prolyl peptide bonds in unfolded and partially folded polypeptide chains and native state proteins. Cyclophilins have been extensively studied, since they are involved in multiple cellular processes related to human pathologies, such as neurodegenerative disorders, infectious diseases, and cancer. However, the presence of cyclophilins in all domains of life indicates a broader biological importance. In this mini-review, we summarize current advances in the study of microbial cyclophilins. Apart from their anticipated role in protein folding and chaperoning, cyclophilins are involved in several other biological processes, such as cellular signal transduction, adaptation to stress, control of pathogens virulence, and modulation of host immune response. Since many existing family members do not have well-defined functions and novel ones are being characterized, the requirement for further studies on their biological role and molecular mechanism of action is apparent. 相似文献