The HtrA family of serine proteases

Mol Microbiol. 1997 Oct;26(2):209-21. doi: 10.1046/j.1365-2958.1997.5601928.x.


HtrA, also known as DegP and probably identical to the Do protease, is a heat shock-induced serine protease that is active in the periplasm of Escherichia coli. Homologues of HtrA have been described in a wide range of bacteria and in eukaryotes. Its chief role is to degrade misfolded proteins in the periplasm. Substrate recognition probably involves the recently described PDZ domains in the C-terminal half of HtrA and, we suspect, has much in common with the substrate recognition system of the tail-specific protease, Prc (which also possesses a PDZ domain). The expression of htrA is regulated by a complex set of signal transduction pathways, which includes an alternative sigma factor, RpoE, an anti-sigma factor, RseA, a two-component regulatory system, CpxRA, and two phosphoprotein phosphatases, PrpA and PrpB. Mutations in the htrA genes of Salmonella, Brucella and Yersinia cause decreased survival in mice and/or macrophages, and htrA mutants can act as vaccines, as cloning hosts and as carriers of heterologous antigens.

Publication types

  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacteria
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Heat-Shock Proteins*
  • Humans
  • Mice
  • Molecular Sequence Data
  • Periplasmic Proteins*
  • Sequence Alignment
  • Serine Endopeptidases* / chemistry
  • Serine Endopeptidases* / genetics
  • Serine Endopeptidases* / metabolism


  • Bacterial Proteins
  • Heat-Shock Proteins
  • Periplasmic Proteins
  • DegP protease
  • Serine Endopeptidases