peptidase C80 cysteine binding domain of RTX toxin RtxA and related proteins
This peptidase C80 family includes the autoproteolytic cysteine protease domain (CPD) of Vibrio cholerae multifunctional autoprocessing repeats-in-toxin (MARTX) toxin that causes disassembly of the actin cytoskeleton and enhances V. cholerae colonization of the small intestine, possibly by facilitating evasion of phagocytic cells. The central region of this toxin is composed of several domains, including the actin cross-linking domain (ACD) that introduces lysine-glutamate cross-links between actin protomers, the Rho-inactivating domain (RID) that disables small Rho GTPases, and an autoprocessing cysteine protease domain (CPD). Within the cell, the CPD is activated by the binding of inositol hexakisphosphate to release individual effector domains of the toxin into the cytosol. The CPD contains the characteristic Cys/His residues in the active site.
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