Enhancement of secretion and extracellular stability of staphylokinase in Bacillus subtilis by wprA gene disruption

Staphylokinase (SAK), a polypeptide secreted by Staphylococcus aureus, is a plasminogen activator with a therapeutic potential in thrombosis diseases. A Bacillus subtilis strain which is multiply deficient in exoproteases was transformed by an expression plasmid carrying a promoter and a signal sequ ence of subtilisin fused in frame with the sak open reading frame. However, the amount of SAK secretion was marginal (45 mg/liter). In contrast, disru ption of the wprA gene, which encodes a subtilisin-type protease, strongly promoted the production of SAK in the stationary phase (181 mg/liter). In a ddition, the extracellular stability of mature SAK. was dramatically enhanc ed. These data indicate a significant role of the wprA gene product in degr ading foreign proteins, both during secretion and in the extracellular mili eu.