title: The Bacillus subtilis extracytoplasmic-function sigmaX factor regulates modification of the cell envelope and resistance to cationic antimicrobial peptides.
abstract: Bacillus subtilis contains seven extracytoplasmic-function sigma factors that activate partially overlapping regulons. We here identify four additional members of the sigma(X) regulon, pbpX (penicillin-binding protein), ywnJ, the dlt operon (D-alanylation of teichoic acids), and the pss ybfM psd operon (phosphatidylethanolamine biosynthesis). Modification of teichoic acids by esterification with D-alanine and incorporation of phosphatidylethanolamine into the cell membrane have a common consequence: in both cases positively charged amino groups are introduced into the cell envelope. The resulting reduction in the net negative charge of the cell envelope has been previously implicated as a resistance mechanism specific for cationic antimicrobial peptides. Consistent with this notion, we find that both sigX and dltA mutants are more sensitive to nisin than wild-type cells. We conclude that activation of the sigma(X) regulon serves to alter cell surface properties to provide protection against antimicrobial peptides.
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, New York 14853-8101, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Cao
authors.forename: John D
authors.initials: JD
authors.lastname: Helmann
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D001433:Bacteriolysis; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D006602:Hexosyltransferases / Q000235:genetics; D008969:Molecular Sequence Data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics; D009876:Operon; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases / Q000235:genetics; D011401:Promoter Regions, Genetic; D018085:Regulon / Q000502:physiology*; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; C093265:SigX protein, Bacillus subtilis; D012808:Sigma Factor; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase