C5a peptidase of Streptococcus pyogenes (ScpA)

C5a peptidase (ScpA) of Streptococcus pyogenes is a highly specific, cell-surface endopeptidase and virulence factor that cleaves the His-Lys bond in the complement component C5a, thereby inactivating its chemotactic and pro-inflammatory functions and blunting neutrophil recruitment to sites of infection. ScpA is also capable of cleaving C3 and C3a, expanding its role in disarming complement-driven host defense. Structurally, ScpA is a multidomain enzyme with a signal peptide, an N-terminal subtilisin-like protease domain, fibronectin type III domains, and cell wall anchoring features; it is expressed on the bacterial surface and functions both enzymatically and as an adhesin/invasin for host interactions. Antibodies targeting ScpA can neutralize its function and have shown protection in animal models, making ScpA a promising candidate for vaccine development against group A streptococcal diseases.

Other names

Streptococcal C5a peptidaseScpASCPAC5a-inactivating enzyme

Proteolysis of C5a (and C3, C3a) to reduce neutrophil chemotaxis and impair host immune response (Targeting the enzyme, e.g., by vaccination, elicits neutralizing antibodies that block this function, restoring immune recruitment to the site of infection)