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

MARCHESINI INES; CONNOLLY J; DELPINO M VICTORIA; BALDI PABLO C; MUJER CESAR; DELVECCCHIO VITO G

PLOS ONE

PUBLIC LIBRARY SCIENCE

Año: 2011 vol. 6 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 amide bond in conjugated bile acids. Bile salt hydrolases are expressed by gastrointestinal bacteria, and they presumably decrease the toxicity of host’s conjugated bile salts. Brucella species are the causative agents of brucellosis, a disease affecting livestock 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. To understand the role CGH plays in B. abortus virulence, we infected phagocytic and epithelial cells with a cgh-deletion mutant (Dcgh) and found that it is defective in its ability to internalize within the host cells. This defect along with the increased resistance of Dcgh to the antimicrobial action of polymyxin B, prompted an analysis of the cell envelope of this mutant. Two-dimensional electrophoretic profiles of Dcgh membrane proteins showed an altered expression of Omp2b and different members of Omp25/31 family. These results were confirmed by Western blot analysis with monoclonal antibodies. Altogether, the results suggest that Brucella CGH not only participates in deconjugation of bile salts but also impacts overall membrane composition and host cell internalization.