Activation of prothrombin by ASP, a serine protease released from Aeromonas sobria

The effect of a serine protease (ASP) secreted from Aeromonas sobria on plasma coagulation was investigated. Proteolytically active ASP promoted human plasma coagulation in a dose-dependent manner. Consistent with the preference for a factor Xa-specific oligo-peptide substrate, ASP produced enzymatic activity from human prothrombin but not from factors IX and X. ASP cleaved prothrombin to produce enzymatically active 37 kDa-fragment displaying the same molecular mass as α-thrombin. ASP is the first bacterial serine protease that produces α-thrombin, through which ASP may contribute to the induction of thrombotic tendency in disseminated intravascular coagulation complicated with sepsis caused by A. sobria infections.