Type

Journal Article

Authors

Colin Hill
Cormac G M Gahan
Roy D. Sleator
Maire Begley

Subjects

Microbiology

Topics
gastrointestinal tract microbiology genetics animals listeria monocytogenes mice mutation trans activators enzymes peptide termination factors sigma factor metabolism penicillin amidase sigb protein bacteria bacterial proteins bile time factors

Contribution of three bile-associated loci, bsh, pva, and btlB, to gastrointestinal persistence and bile tolerance of Listeria monocytogenes. (2005)

Abstract Listeria monocytogenes must resist the deleterious actions of bile in order to infect and subsequently colonize the human gastrointestinal tract. The molecular mechanisms used by the bacterium to resist bile and the influence of bile on pathogenesis are as yet largely unexplored. This study describes the analysis of three genes--bsh, pva, and btlB--previously annotated as bile-associated loci in the sequenced L. monocytogenes EGDe genome (lmo2067, lmo0446, and lmo0754, respectively). Analysis of deletion mutants revealed a role for all three genes in resisting the acute toxicity of bile and bile salts, particularly glycoconjugated bile salts at low pH. Mutants were unaffected in the other stress responses examined (acid, salt, and detergents). Bile hydrolysis assays demonstrate that L. monocytogenes possesses only one bile salt hydrolase gene, namely, bsh. Transcriptional analyses and activity assays revealed that, although it is regulated by both PrfA and sigma(B), the latter appears to play the greater role in modulating bsh expression. In addition to being incapable of bile hydrolysis, a sigB mutant was shown to be exquisitely sensitive to bile salts. Furthermore, increased expression of sigB was detected under anaerobic conditions and during murine infection. A gene previously annotated as a possible penicillin V amidase (pva) or bile salt hydrolase was shown to be required for resistance to penicillin V but not penicillin G but did not demonstrate a role in bile hydrolysis. Finally, animal (murine) studies revealed an important role for both bsh and btlB in the intestinal persistence of L. monocytogenes.
Collections Ireland -> University College Cork -> PubMed

Full list of authors on original publication

Colin Hill, Cormac G M Gahan, Roy D. Sleator, Maire Begley

Experts in our system

1
Colin Hill
University College Cork
Total Publications: 351
 
2
Cormac G M Gahan
University College Cork
Total Publications: 109
 
3
Roy D. Sleator
University College Cork
Total Publications: 44
 
4
Maire Begley
University College Cork
Total Publications: 27