Brucella abortus Choloylglycine Hydrolase Affects Cell Envelope Composition and Host Cell Internalization.

MARCHESINI, MARÍA INÉS; CONNOLLY JOSEPH; M. VICTORIA DELPINO; PABLO C. BALDI.; CESAR V. MUJER; VITO G. DELVECCHIO; DIEGO COMERCI

PLOS ONE

PUBLIC LIBRARY SCIENCE

Año: 2011 p. 1 - 10

1932-6203

Choloylglycine hydrolase (CGH, E.C. 3.5.1.24) is a conjugated bile salt hydrolase that catalyses the hydrolysis of the amidebond in conjugated bile acids. Bile salt hydrolases are expressed by gastrointestinal bacteria, and they presumably decreasethe toxicity of host?s conjugated bile salts. Brucella species are the causative agents of brucellosis, a disease affectinglivestock and humans. CGH confers Brucella the ability to deconjugate and resist the antimicrobial action of bile salts,contributing to the establishment of a successful infection through the oral route in mice. Additionally, cgh-deletion mutantwas also attenuated in intraperitoneally inoculated mice, which suggests that CGH may play a role during systemic infectionother than hydrolyzing conjugated bile acids. To understand the role CGH plays in B. abortus virulence, we infectedphagocytic and epithelial cells with a cgh-deletion mutant (Dcgh) and found that it is defective in the internalizationprocess. This defect along with the increased resistance of Dcgh to the antimicrobial action of polymyxin B, prompted ananalysis of the cell envelope of this mutant. Two-dimensional electrophoretic profiles of Dcgh cell envelope-associatedproteins showed an altered expression of Omp2b and different members of the Omp25/31 family. These results wereconfirmed by Western blot analysis with monoclonal antibodies. Altogether, the results indicate that Brucella CGH not onlyparticipates in deconjugation of bile salts but also affects overall membrane composition and host cell internalization.