Peptidase S1C, DegS (IPR011783)

Short name: Pept_S1C_DegS

Overlapping homologous superfamilies

Family relationships


Proteolytic enzymes that exploit serine in their catalytic activity are ubiquitous, being found in viruses, bacteria and eukaryotes [PMID: 7845208]. They include a wide range of peptidase activity, including exopeptidase, endopeptidase, oligopeptidase and omega-peptidase activity. Many families of serine protease have been identified, these being grouped into clans on the basis of structural similarity and other functional evidence [PMID: 7845208]. Structures are known for members of the clans and the structures indicate that some appear to be totally unrelated, suggesting different evolutionary origins for the serine peptidases [PMID: 7845208].

Not withstanding their different evolutionary origins, there are similarities in the reaction mechanisms of several peptidases. Chymotrypsin, subtilisin and carboxypeptidase C have a catalytic triad of serine, aspartate and histidine in common: serine acts as a nucleophile, aspartate as an electrophile, and histidine as a base [PMID: 7845208]. The geometric orientations of the catalytic residues are similar between families, despite different protein folds [PMID: 7845208]. The linear arrangements of the catalytic residues commonly reflect clan relationships. For example the catalytic triad in the chymotrypsin clan (PA) is ordered HDS, but is ordered DHS in the subtilisin clan (SB) and SDH in the carboxypeptidase clan (SC) [PMID: 7845208, PMID: 8439290].

This family consists of the periplasmic serine protease DegS (HhoB). They belong to MEROPS peptidase family S1, subfamily S1C (protease Do, clan PA(S)). They are a shorter paralogs of protease Do (HtrA, DegP) and DegQ (HhoA). They are found in Escherichia coli and several of the gammaproteobacteria. DegS contains a trypsin domain and a single copy of PDZ domain (in contrast to DegP with two copies). A critical role of this DegS is to sense stress by detecting misfolded proteins in the periplasm. DegS then cleaves the periplasmic domain of RseA, a transmembrane protein and inhibitor of sigmaE, activating the sigmaE-driven expression of periplasmic proteases/chaperones [PMID: 11442831, PMID: 12679025, PMID: 17360428].

GO terms

Biological Process

GO:0006508 proteolysis

Molecular Function

GO:0004252 serine-type endopeptidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.