Homologous Superfamily

Outer membrane adhesin/peptidase omptin (IPR020080)

Short name: OM_adhesin/peptidase_omptin

Overlapping entries


This entry represents a transmembrane domain with a (10,12) beta-barrel structure. This domain is found in:

  • Outer membrane peptidase omptin
  • Outer membrane adhesin OpcA

The outer membrane omptin belongs to the MEROPS family A26 (clan AF). The omptin family, comprises a number of novel outer membrane-associated serine peptidases that are distinct from trypsin-like peptidases in that they cleave polypeptides between two basically-charged amino acids [PMID: 3056908]. The enzyme is sensitive to the serine protease inhibitor diisopropylfluoro-phosphate, to divalent cations such as copper, zinc and iron [PMID: 3056908], and is temperature regulated, activity decreasing at lower temperatures [PMID: 3056908, PMID: 8288530]. Temperature regulation is most prominently shown in the Yersinia pestis coagulase/fibrinolysin protein, where coagulase activity is prevalent below 30 degrees Celsius, and fibrinolysin (protease) activity is prevalent above this point, the optimum temperature being 37 degrees [PMID: 2526282]. It is possible that this assists in 'flea blockage' and transmission of the bacteria to animals [PMID: 2526282].

The outer membrane adhesin OpcA is Neisseria species-specific. OpcA (formerly called 5C) was isolated from Neisseria meningitidis, causative agent of meningococcal meningitis and septicemia. An outer membrane protein embedded in the lipid bilayer, OpcA was shown to play an important role in meningococcal adhesion and invasion of both epithelial and endothelial cells, mediating attachment to host cells by binding proteoglycan cell-surface receptors [PMID: 12706886]. OpcA forms a 10-stranded beta-barrel with five highly mobile extracellular loops that protrude above the surface of the membrane [PMID: 11891340]. These extracellular loops combine to form a crevice in the external surface that is lined by positively charged residues, which is predicted to be a binding site for proteoglycan polysaccharides involved in pathogenesis. Conformational changes in the extracellular loops modulate the surface of OpcA, which could affect the proteoglycan binding site [PMID: 17114231]. These conformational changes could also lead to pore opening.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0004190 aspartic-type endopeptidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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