scholarly journals Hydrogen sulfide is a novel potential virulence factor ofMycoplasma pneumoniae: characterization of the unusual cysteine desulfurase/desulfhydrase HapE

2016 ◽  
Vol 100 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Stephanie Großhennig ◽  
Till Ischebeck ◽  
Johannes Gibhardt ◽  
Julia Busse ◽  
Ivo Feussner ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Virulence Factor ◽  
Cysteine Desulfurase ◽  
Potential Virulence Factor

scholarly journals Molecular and Functional Characterization of a ToxR-Regulated Lipoprotein from a Clinical Isolate of Aeromonas hydrophila

2006 ◽  
Vol 74 (7) ◽  
pp. 3742-3755 ◽  
Author(s):  
Lakshmi Pillai ◽  
Jian Sha ◽  
Tatiana E. Erova ◽  
Amin A. Fadl ◽  
Bijay K. Khajanchi ◽  
...  
Keyword(s):  
Virulence Factor ◽  
Aeromonas Hydrophila ◽  
Functional Characterization ◽  
Affinity Column ◽  
Serum Resistance ◽  
Classical Pathway ◽  
Dependent Manner ◽  
T7 Promoter

ABSTRACT Human diseases caused by species of Aeromonas have been classified into two major groups: septicemia and gastroenteritis. In this study, we reported the molecular and functional characterization of a new virulence factor, ToxR-regulated lipoprotein, or TagA, from a diarrheal isolate, SSU, of Aeromonas hydrophila. The tagA gene of A. hydrophila exhibited 60% identity with that of a recently identified stcE gene from Escherichia coli O157:H7, which encoded a protein (StcE) that provided serum resistance to the bacterium and prevented erythrocyte lysis by controlling classical pathway of complement activation by cleaving the complement C1-esterase inhibitor (C1-INH). We purified A. hydrophila TagA as a histidine-tagged fusion protein (rTagA) from E. coli DE3 strain using a T7 promoter-based pET30 expression vector and nickel affinity column chromatography. rTagA cleaved C1-INH in a time-dependent manner. The tagA isogenic mutant of A. hydrophila, unlike its corresponding wild-type (WT) or the complemented strain, was unable to cleave C1-INH, which is required to potentiate the C1-INH-mediated lysis of host and bacterial cells. We indeed demonstrated colocalization of C1-INH and TagA on the bacterial surface by confocal fluorescence microscopy, which ultimately resulted in increased serum resistance of the WT bacterium. Likewise, we delineated the role of TagA in contributing to the enhanced ability of C1-INH to inhibit the classical complement-mediated lysis of erythrocytes. Importantly, we provided evidence that the tagA mutant was significantly less virulent in a mouse model of infection (60%) than the WT bacterium at two 50% lethal doses, which resulted in 100% mortality within 48 h. Taken together, our data provided new information on the role of TagA as a virulence factor in bacterial pathogenesis. This is the first report of TagA characterization from any species of Aeromonas.

scholarly journals Molecular Characterization of a Flagellar Export Locus of Helicobacter pylori

1999 ◽  
Vol 67 (5) ◽  
pp. 2060-2070 ◽  
Author(s):  
Steffen Porwollik ◽  
Brian Noonan ◽  
Paul W. O’Toole
Keyword(s):  
Helicobacter Pylori ◽  
Virulence Factor ◽  
Housekeeping Genes ◽  
Reading Frame ◽  
Reverse Transcription Pcr ◽  
Mutant Strains ◽  
H Pylori ◽  
Export Protein ◽  
Successful Colonization

ABSTRACT Motility of Helicobacter species has been shown to be essential for successful colonization of the host. We have investigated the organization of a flagellar export locus in Helicobacter pylori. A 7-kb fragment of the H. pylori CCUG 17874 genome was cloned and sequenced, revealing an operon comprising an open reading frame of unknown function (ORF03), essential housekeeping genes (ileS and murB), flagellar export genes (fliI and fliQ), and a homolog to a gene implicated in virulence factor transport in other pathogens (virB11). A promoter for this operon, showing similarity to the Escherichia coli ς70 consensus, was identified by primer extension. Cotranscription of the genes in the operon was demonstrated by reverse transcription-PCR, and transcription of virB11, fliI, fliQ, andmurB was detected in human or mouse biopsies obtained from infected hosts. The genetic organization of this locus was conserved in a panel of H. pylori clinical isolates. EngineeredfliI and fliQ mutant strains were completely aflagellate and nonmotile, whereas a virB11 mutant still produced flagella. The fliI and fliQ mutant strains produced reduced levels of flagellin and the hook protein FlgE. Production of OMP4, a member of the outer membrane protein family identified in H. pylori 26695, was reduced in both thevirB11 mutant and the fliI mutant, suggesting related functions of the virulence factor export protein (VirB11) and the flagellar export component (FliI).

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