Table 1.

Major secreted extracellular bacterial proteases of Pseudomonas aeruginosa and Staphylococcus aureus, their substrate specificities, and associated biological processes

Organism	Bacterial Protease	MEROPS Family	Protease Class	Substrate	Associated Process	References
P. aeruginosa	Elastase A (LasA)	M23	Metallo-	Fibrinogen, elastin	ECM destruction	16,52
	Elastase B (Las B)	M4	Metallo-	Elastin, collagen III, collagen IV, MMP-1/MMP-9 (proenzyme), elastase B	ECM destruction, MMP proteolysis, autoproteolytic processing	16,53
	Alkaline protease (AprA)	M10	Metallo-	Fibrinogen, gelatin, casein, hemoglobin, cytokines	Complement inactivation, host immune evasion	16,54,55
	Protease IV	S1	Serine-	Plasminogen, fibrinogen, complement protein C3	Complement inactivation	16,56
S. aureus	Aureolysin	M4	Metallo-	Plasminogen, complement protein C3	Complement inactivation	16,23,57
	Staphopain A (ScpA)	C47	Cysteine-	Elastin	ECM destruction	16
	Staphopain B (SspB)	C47	Cysteine-	Fibrinogen, fibronectin, elastin	ECM destruction, complement inactivation	16,57
	Staphylococcal serine protease (SspA)	S1	Serine-	Actin, collagenase, IgG1 heavy chain, serum albumin, vimentin, casein	Host immune evasion, ECM degradation	16,57,58

ECM, extracellular matrix; MMP, matrix metalloproteinase.