Salmonella SsrB activates a global regulon of horizontally acquired genes

Micah J. Worley, Katherine H.L. Ching, Fred Heffron

    Research output: Contribution to journalArticlepeer-review

    172 Scopus citations


    Salmonella enterica is a bacterial pathogen of humans that can proliferate within epithelial cells as well as professional phagocytes of the immune system. This ability requires an S. enterica specific locus termed Salmonella pathogenicity island 2 (SPI-2). SPI-2 encodes a type III secretion system that injects effecters encoded within the island into host cell cytosol to promote virulence. SsrAB is a two-component regulator encoded within SPI-2 that was assumed to activate SPI-2 genes exclusively. Here, it is shown that SsrB in fact activates a global regulon. At least 10 genes outside SPI-2 are SsrB regulated within epithelial and macrophage cells. Nine of these 10 SsrB-regulated genes outside SPI-2 reside within previously undescribed regions of the Salmonella genome. Most share no sequence homology with current database entries. However, one is remarkably homologous to human glucosyl ceramidase, an enzyme involved in the ceramide signalling pathway. The SsrB regulon is modulated by the two-component regulatory systems PhoP/PhoQ and OmpR/ EnvZ, and is upregulated in the intracellular microenvironment.

    Original languageEnglish (US)
    Pages (from-to)749-761
    Number of pages13
    JournalMolecular Microbiology
    Issue number3
    StatePublished - 2000

    ASJC Scopus subject areas

    • Microbiology
    • Molecular Biology


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