Open AccessRegulation of Mannose Phosphotransferase System Permease and Virulence Gene Expression in Listeria monocytogenes by the EII t Man Transporter
Author(s) -
Hung Vu-Khac,
Kurt W. Miller
Publication year - 2009
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.01104-09
Subject(s) - operon , pep group translocation , permease , mutant , biology , virulence , mannose , repressor , gene , microbiology and biotechnology , glucose transporter , catabolite repression , gene expression , phosphotransferase , regulator gene , biochemistry , insulin , endocrinology
The EIIt Man phosphotransferase system (PTS) permease encoded by thempt operon is the principal glucose transporter inListeria monocytogenes. EIIt Man participates in glucose-mediated carbon catabolite repression (CCR) and downregulation of virulence gene expression, and it is the receptor for class IIa bacteriocins. The regulation of this important protein and its roles in gene control were examined using derivatives of strain EGD-e in which thempt operon or its regulatory genes,manR and lmo0095, were deleted. Real-time reverse transcription-PCR analysis showed that thempt mRNA level was 10- and 100-fold lower in the lmo0095 andmanR deletion strains, respectively. ThemanR mRNA level was higher in thempt deletion mutant in medium lacking glucose, possibly due to disruption of a regulatory process that normally downregulatesmanR transcription in the absence of this sugar. Analysis of thempt deletion mutant also showed that EIIt Man participates to various degrees in glucose-mediated CCR of PTS operons. CCR of the lmo0027 gene, which encodes a β-glucoside PTS transporter, required expression of EIIt Man . In contrast, genes in two mannose PTS operons (lmo0024, lmo1997, and lmo2002) were repressed by glucose even when EIIt Man was not synthesized. A third mannose PTS operon,mpo , was not regulated by glucose or by the level of EIIt Man . Finally, the mRNA levels for five genes in theprfA virulence gene cluster were two- to fourfold higher in thempt deletion mutant. The results show that EIIt Man participates to various extents in glucose-mediated CCR of PTS operons and makes a small, albeit significant, contribution to downregulation of virulence gene transcription by glucose in strain EGD-e.