Components of the peptidoglycan-recycling pathway modulate invasion and intracellular survival of Salmonella enterica serovar Typhimurium

Anders Folkesson, Sofia Eriksson, Mats Andersson, James T. Park, Staffan Normark

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Summary β-Lactam resistance in enteric bacteria is frequently caused by mutations in ampD encoding a cytosolic N-acetylmuramyl-l-alanine amidase. Such mutants are blocked in murein (peptidoglycan) recycling and accumulate cytoplasmic muropeptides that interact with the transcriptional activator ampR, which de-represses β-lactamase expression. Salmonella enterica serovar Typhimurium, an extensively studied enteric pathogen, was used to show that mutations in ampD decreased the ability of S. typhimurium to enter a macrophage derived cell line and made the bacteria more potent as inducers of inducible nitric oxide synthase (iNOS), as compared with the wild-type. ampG mutants, defective in the transport of recycled muropeptides across the cytoplasmic membrane, behaved essentially as the wild-type in invasion assays and in activation of iNOS. As ampD mutants also have reduced in vivo fitness in a murine model, we suggest that the cytoplasmic accumulation of muropeptides affects the virulence of the ampD mutants.
Original languageEnglish
JournalCellular Microbiology
Volume7
Issue number1
Pages (from-to)147-155
ISSN1462-5814
DOIs
Publication statusPublished - 2005
Externally publishedYes

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