PROSITE documentation PDOC51691
Peptidase family S6 domain profile


Autotransporters (ATs) represent a large superfamily of virulence factors produced by Gram-negative bacteria. ATs have evolved a unique export mechanism. Initially the protein is synthetized with an N-terminal leader peptide directing the protein to the periplasm via the signal recognition particle. Once accross the inner membrane, the C-terminal domain form a β-barrel structure (see <PDOC51208>) allowing the passenger domain to escape to the external medium, where it is released proteolytically from the cell. The 300-residue peptidase family S6 domain is found in a subfamily of autotransporter including:

  • Neisseria gonorrhoeae IgA-specific serine endopeptidase autotransporter.
  • Haemophilus influenzae immunoglobulin A1 protease autotransporter.
  • Enteropathogenic Escherichia coli serine protease EspC.
  • Enterohemorrhagic Escherichia coli serine protease EspP.
  • Enteroaggregative Escherichia coli plasmid-encoded toxin (Pet).
  • Uropathogenic Escherichia coli serine protease Sat autotransporter.
  • Pathogenic Escherichia coli hemoglobin-binding protease Hbp autotransporter.
  • Avian pathogenic Escherichia coli temperature-sensitive hemagglutinin Tsh autotransporter.
  • Avian pathogenic Escherichia coli Vat.
  • Shigella flexneri serine protease Pic autotransporter.
  • Shigella flexneri serine protease SepA autotransporter.

The peptidase family S6 domain mediates intermolecular autoproteolysis, resulting in release of the passenger domain from the bacterial surface. It has a globular shape including six β strands rolled into a barrel-like structure with several long β hairpins over its surface (see <PDB:1WXR>). The catalytic triad is composed of Ser, Asp, and His [1,2,3].

The peptidase family S6 is a member of the SA (chymotrypsin) clan [1,E1].

The profile we developed covers the entire peptidase family S6 domain.

Last update:

November 2013 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

PEPTIDASE_S6, PS51691; Peptidase family S6 domain profile  (MATRIX)


1AuthorsFink D.L. Cope L.D. Hansen E.J. St Geme J.W. III
TitleThe Hemophilus influenzae Hap autotransporter is a chymotrypsin clan serine protease and undergoes autoproteolysis via an intermolecular mechanism.
SourceJ. Biol. Chem. 276:39492-39500(2001).
PubMed ID11504735

2AuthorsOtto B.R. Sijbrandi R. Luirink J. Oudega B. Heddle J.G. Mizutani K. Park S.-Y. Tame J.R.H.
TitleCrystal structure of hemoglobin protease, a heme binding autotransporter protein from pathogenic Escherichia coli.
SourceJ. Biol. Chem. 280:17339-17345(2005).
PubMed ID15728184

3AuthorsMeng G. Spahich N. Kenjale R. Waksman G. St Geme J.W. III
TitleCrystal structure of the Haemophilus influenzae Hap adhesin reveals an intercellular oligomerization mechanism for bacterial aggregation.
SourceEMBO J. 30:3864-3874(2011).
PubMed ID21841773


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