Streptococcal pyrogenic exotoxin B (SpeB)

Streptococcal pyrogenic exotoxin B (SpeB), also known as streptococcal cysteine protease, is a secreted enzyme produced by Streptococcus pyogenes. It is a member of the papain-like family of cysteine proteases and is a major virulence factor implicated in invasive diseases such as necrotizing fasciitis. SpeB is synthesized as an inactive zymogen that is converted to its active protease form by autolytic cleavage. It cleaves a broad spectrum of host and bacterial proteins, facilitating tissue invasion, immune evasion, and pathology. Structurally, SpeB is a distant homolog of papain and cathepsins, but it forms a unique class among prokaryotic proteases. Its notable features include a non-canonical catalytic triad and the presence of an integrin-binding RGD motif, which may further contribute to its pathogenesis[1][2][8][9].

Other names

Streptococcal cysteine proteaseStreptococcal pyrogenic exotoxin BSCPSpeB

Inhibition of protease active site (cysteine protease inhibitors binding to catalytic cysteine)