PrfA*-expressing Listeria monocytogenes cells are more sensitive to pediocin-like peptides despite impaired expression of the bacteriocin receptor

FARIZANO J; MASIAS E; MINAHK C; SAAVEDRA L

Ciudad Autonoma de Buenos Aires

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Class IIabacteriocins are antimicrobial peptides produced by Lactic AcidBacteria. The accepted mechanism of action involves thepermeabilization of plasma membrane, where the mannosephosphotransferase complex (Man-PTS) act as the bacteriocin receptor.As a matter of fact, the lack ofexpression of thiscomplex renders cells highly resistant to these peptides. The invitro studies on class IIa bacteriocins conducted so far dealt withbacteria in saprophytic state. Therefore, the main objective of thisstudy was to characterize the sensitivity of L. monocytogenes cellsexpressing a virulent phenotype. For that purpose, we obtained cellsthat constitutively express an active form of the master regulator ofListeria virulence (PrfA*) by means of the Pnf1002 vector. Asexpected, the qPCR gene expression assay of the Man-PTS subunits IICand IID showed that those genes were downregulated in PrfA* cells. Wecomplemented these results with a proteomic analysis of the plasmamembranes. However, to oursurprise, we found that these cells were more sensitive topediocin-like peptides. Biophysical assaysshowed that membranes from PrfA*-expressing cells seemed to bestiffer and less compressible than the wild type cell ones.Furthermore, we performed a lipidomic analysis to determine the lipidcomposition of the membranes from the strains under study. This workrepresents the first report on the susceptibility of virulent L.monocytogenes to pediocin-like bacteriocins.p { margin-bottom: 0.25cm; line-height: 115%; }