Cloning, Expression and Characterization of a Novel Fibrinolytic Serine Metalloproteinase from Bacillus velezensis SW5

A novel fibrinolytic serine metalloproteinase gene (aprx-sw5) from Bacillus velezensis SW5 was heterologously expressed in Escherichia coli Trans(DE3). Sequence analysis indicated that the open reading frame of aprx-sw5 had 1329 bp, encoding a protein of 442 amino acid residues. In silico analysis described 3D structure of AprX-SW5 for the fist time. The recombinant AprX-SW5 was purified with the molecular weight of 47 kDa. The optimum pH and temperature were 8.0 and 60°C, respectively. The enzyme was significantly activated by Mn2+, almost completely inhibited by PMSF and EDTA, but tolerant to non-ionic surfactants, such as 1% Tween 40, 1% Tween 60 and 1% Tween 80. The enzyme activity was greatly affected by DDT and SDS at the final concentrations of 5 mM. AprX-SW5 retained 81, 48, and 30% relative enzyme activities after incubation with 0.5, 1.0, and 2.0 M NaCl at 4°C for 12 h, respectively. The specific activity of 952 U/mg was evaluated for purified enzyme using fibrin as the substrate. This study indicated that AprX-SW5 may be a potential candidate for use in thrombolytic therapy.