Expression of the streptokinase gene from Streptococcus equisimilis in Bacillus subtilis

The previously cloned and sequenced streptokinase gene (skc) from Streptococcus equisimilis H46A was inserted into plasmid vectors capable of replication in Bacillus subtilis. The skc gene was expressed by use of its own transcription and translation signals which appeared to meet the stringent requirements of B. subtilis for efficient foreign gene expression. The secreted streptokinase activity began to decline toward the end of the exponential growth phase suggesting that B. subtilis exoproteases hydrolyzed and inactivated the foreign protein.