Down-regulation of RpoN-controlled genes protects Salmonella cells from killing by the cationic antimicrobial peptide polymyxin B

BARCHIESI, JULIETA; ESPARIZ, MARTÍN; CHECA, SUSANA K.; SONCINI, FERNANDO C.

FEMS MICROBIOLOGY LETTERS

Blackwell Publishing Ltd.

Lugar: Oxford; Año: 2009 vol. 291 p. 73 - 79

0378-1097

Calification SCImago-Q2, IF (2009) 2.199. Salmonella enterica polymyxin B (PM) resistance is modulated mainly by substitutions of the acyl chains and the phosphate groups on the lipid A moiety of lipopolysaccharide. These modifications are mediated by genes under the control of the PmrA/PmrB and PhoP/PhoQ two-component regulatory systems. In this study, a deletion in the gene encoding the alternative sigma 54 factor, rpoN, was shown to increase PM resistance without affecting protamine sensitivity. The results presented here showed that the increased polymyxin resistance observed in the "delta"rpoN mutant occurs through a PmrA/PhoP-independent pathway. Downregulation of one or more genes belonging to the RpoN regulon may provide an additional mechanism of defence against membrane-permeabilizing antimicrobial peptides that helps the pathogen to survive in different environments.