Molecular and Functional Characterization of a ToxR-Regulated Lipoprotein from a Clinical Isolate of Aeromonas hydrophila
- 1 July 2006
- journal article
- Published by American Society for Microbiology in Infection and Immunity
- Vol. 74 (7), 3742-3755
- https://doi.org/10.1128/iai.00402-06
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 .Keywords
This publication has 49 references indexed in Scilit:
- Potentiation of C1 Esterase Inhibitor by StcE, a Metalloprotease Secreted by Escherichia coli O157:H7The Journal of Experimental Medicine, 2004
- Environmental Genome Shotgun Sequencing of the Sargasso SeaScience, 2004
- Reactivity of Convalescent-Phase Hemolytic-Uremic Syndrome Patient Sera with the Megaplasmid-Encoded TagA Protein of Shiga Toxigenic Escherichia coli O157Journal of Clinical Microbiology, 2002
- Regulation of the Cytotoxic Enterotoxin Gene in Aeromonas hydrophila : Characterization of an Iron Uptake RegulatorInfection and Immunity, 2001
- Detection ofAeromonas hydrophilain a drinking- water distribution system: a field and pilot studyCanadian Journal of Microbiology, 2001
- Isolation and characterization of a Vibrio cholerae gene (tagA) that encodes a ToxR-regulated lipoproteinGene, 1995
- The role of lipopolysaccharide in complement-killing of Aeromonas hydrophila strains of serotype O:34Journal of General Microbiology, 1991
- Cloning and characterization of an extracellular temperature-labile serine protease gene fromAeromonas hydrophilaFEMS Microbiology Letters, 1991
- Cloning and characterization of an extracellular temperature-labile serine protease gene from Aeromonas hydrophilaFEMS Microbiology Letters, 1991
- Pathogenic potentials of bacterial proteasesClinica Chimica Acta; International Journal of Clinical Chemistry, 1989