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- Title
Differential roles of multiple signal peptidases in the virulence of Listeria monocytogenes.
- Authors
Bonnemain, Claire; Raynaud, Catherine; Réglier-Poupet, Hélène; Dubail, Iharilalao; Frehel, Claude; Lety, Marie-Annick; Berche, Patrick; Charbit, Alain
- Abstract
Most bacteria contain one type I signal peptidase (Spase I) for cleavage of signal peptides from exported and secreted proteins. Here, we identified a locus encoding three contiguous Spase I genes in the genome of Listeria monocytogenes. The deduced Sip proteins (denoted SipX, SipY and SipZ) are significantly similar to SipS and SipT, the major SPase I proteins of Bacillus subtilis (38% to 44% peptidic identity) . We studied the role of these multiple signal peptidases in bacterial pathogenicity by constructing a series of single- and double-chromosomal knock-out mutants. Inactivation of sipX did not affect intracellular multiplication of L. monocytogenes but significantly reduced bacterial virulence ( ∼ 100-fold). Inactivation of sipZ impaired the secretion of phospholipase C (PC-PLC) and listeriolysin O (LLO), restricted intracellular multiplication and almost abolished virulence (LD50 of 108.3), inactivation of sipY had no detectable effects. Most importantly, a mutant expressing only SipX was impaired in intracellular survival and strongly attenuated in the mouse (LD50 of 107.2), whereas, a mutant expressing only SipZ behaved like wild-type EGD in all the assays performed. The data establish that SipX and SipZ perform distinct functions in bacterial pathogenicity and that SipZ is the major Spase I of L. monocytogenes. This work constitutes the first report on the differential role of multiple Spases I in a pathogenic bacterium and suggests a possible post-translational control mechanism of virulence factors expression.
- Subjects
LISTERIA monocytogenes; SIGNAL peptidases; ENDOPEPTIDASES; BACTERIAL proteins; MICROBIAL enzymes; ENZYMES
- Publication
Molecular Microbiology, 2004, Vol 51, Issue 5, p1251
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.2004.03916.x