The Genus Yersinia

Volume 603 of the series Advances In Experimental Medicine And Biology pp 211-216

Environmental Stimuli Affecting Expression of the Ysa Type Three Secretion Locus

  • Shirly Mildiner-EarleyAffiliated withMolecular Microbiology, Washington University
  • , Virginia L. MillerAffiliated withMolecular Microbiology and Pediatrics, Washington University
  • , Kimberly A. WalkerAffiliated withMolecular Microbiology, Washington University

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Yersinia enterocolitica has two type III secretion systems (TTSS): The well characterized Ysc-Yop system and the relatively uncharacterized Ysa-Ysp system. Detection of Ysps in culture supernatants has only been observed in vitro when cultures are grown at low temperature (26°C) and in high salt (290mM NaCl). Previous reports demonstrated that expression from the ysaE promoter was activated by high salt. In this study, we report a new environmental stimulus for ysa gene expression; in the presence of high salt, growth on solid surface stimulates expression 7-fold compared to growth in high salt broth. These new data indicate that, in the presence of salt, solid surface is an extremely robust signal for the Ysa system.