Chaperone release and unfolding of substrates in type III secretion

Nature. 2005 Oct 6;437(7060):911-5. doi: 10.1038/nature03992.


Type III protein secretion systems are essential virulence factors of many bacteria pathogenic to humans, animals and plants. These systems mediate the transfer of bacterial virulence proteins directly into the host cell cytoplasm. Proteins are thought to travel this pathway in a largely unfolded manner, and a family of customized cytoplasmic chaperones, which specifically bind cognate secreted proteins, are essential for secretion. Here we show that InvC, an ATPase associated with a Salmonella enterica type III secretion system, has a critical function in substrate recognition. Furthermore, InvC induces chaperone release from and unfolding of the cognate secreted protein in an ATP-dependent manner. Our results show a similarity between the mechanisms of substrate recognition by type III protein secretion systems and AAA + ATPase disassembly machines.

Publication types

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

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Chaperonin 60 / chemistry
  • Chaperonin 60 / metabolism
  • Molecular Chaperones / chemistry
  • Molecular Chaperones / metabolism*
  • Protein Folding*
  • Protein Tyrosine Phosphatases / chemistry
  • Protein Tyrosine Phosphatases / metabolism
  • Proton-Translocating ATPases / metabolism
  • Salmonella enterica / chemistry
  • Salmonella enterica / enzymology
  • Salmonella enterica / metabolism*
  • Salmonella enterica / pathogenicity
  • Substrate Specificity
  • Virulence Factors / chemistry
  • Virulence Factors / metabolism


  • Bacterial Proteins
  • Chaperonin 60
  • Molecular Chaperones
  • Virulence Factors
  • Protein Tyrosine Phosphatases
  • sptP protein, Salmonella typhimurium
  • Proton-Translocating ATPases