Immunoglobulin A protease (IgA protease)

Immunoglobulin A protease (commonly known as IgA protease) is an enzyme secreted by pathogenic bacteria such as Neisseria gonorrhoeae, Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae[4]. The enzyme specifically cleaves the hinge region of the human immunoglobulin A1 (IgA1) antibody, a major antibody involved in mucosal immunity, by targeting proline-, serine-, and threonine-rich sequences found only in IgA1[4][6][8]. This proteolytic activity enables bacteria to evade the host immune system by inactivating IgA1, facilitating bacterial colonization and persistence at mucosal surfaces[1][4]. IgA proteases belong to several enzyme classes, including serine proteases, metalloproteases, and cysteine proteases, and share a modular architecture with distinct catalytic and transport domains (often secreted via the type V [autotransporter] secretion system)[1][6][8]. These enzymes are considered important virulence factors and potential therapeutic targets for treating infections caused by the above pathogens[6]. No approved drugs currently target IgA protease, but specific inhibitors have been studied in experimental models[6]. Key features: - The enzyme’s substrate is human IgA1 (not IgA2), and no small-molecule substrates are known[4]. - The protease is highly specific due to its unique active site structure and gating mechanisms, which only allow cleavage when the correct substrate (IgA1) is bound[8]. - IgA proteases are considered major virulence determinants among bacteria that express them, making them critical for pathogenesis and an attractive target in antimicrobial research[1][6][4].

Other names

IgA1 proteaseIgA-specific serine endopeptidaseIgA proteinaseIgA-specific proteinaseimmunoglobulin A proteaseimmunoglobulin A proteinaseIgAse Pro-Pro-Y-Pro

Proteolytic cleavage of the proline-rich hinge region of human IgA1, disruption of antibody-mediated immune defense, enzymatic degradation of host defense proteins[4][6][8]