The psp locus of Yersinia enterocolitica is required for virulence and for growth in vitro when the Ysc type III secretion system is produced

Mol Microbiol. 2001 Jan;39(2):429-44. doi: 10.1046/j.1365-2958.2001.02235.x.


The phage shock protein locus (pspFpspABCDE) of Escherichia coli has proved to be something of an enigma since its discovery. The physiological functions of the psp locus, including those of the predicted effector protein PspA, are unknown. In a previous genetic screen, we determined that a Yersinia enterocolitica pspC mutant was severely attenuated for virulence. In this study, the psp locus of Y. enterocolitica was characterized further. The pspC gene of Y. enterocolitica was found to be important for normal growth when the Ysc type III secretion system was expressed in the laboratory. This growth defect was specifically caused by production of the secretin protein, YscC. Expression of the psp genes was induced when the type III secretion system was functional or when only the yscC gene was expressed. This induction of psp gene expression required a functional pspC gene. Most significantly, evidence suggests that the expression of at least one gene that is not part of the psp locus is regulated by Psp proteins. This unidentified gene (or genes) may also be important for growth when the type III secretion system is expressed. These conclusions are supported by the effects of various psp mutations on virulence. This is the first indication that Psp proteins might be involved in the regulation of genes besides the psp locus itself.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bacterial Proteins / biosynthesis*
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism
  • Mice
  • Mutation
  • Plasmids
  • Transcription, Genetic
  • Virulence
  • Yersinia Infections / microbiology
  • Yersinia enterocolitica / genetics*
  • Yersinia enterocolitica / growth & development
  • Yersinia enterocolitica / pathogenicity*


  • Bacterial Proteins
  • Heat-Shock Proteins
  • phage shock protein, Bacteria
  • pneumococcal surface protein A