Secretion of Escherichia coli beta-lactamase from Bacillus subtilis by the aid of alpha-amylase signal sequence.

We describe a secretion vector system for introducing foreign genes into Bacillus subtilis. We constructed secretion vectors from the plasmid pUB110 and the promoter and signal sequence region of the alpha-amylase gene from Bacillus amyloliquefaciens. Foreign structural genes can be inserted into the various vectors after the signal sequence region of the alpha-amylase gene. Demonstrating secretion of a foreign gene product from Bacillus, we here report that the Escherichia coli beta-lactamase gene, devoid of its own signal sequence coding region, can be expressed in B. subtilis by the aid of the secretion vectors so that greater than 95% of the enzyme activity is secreted to the growth medium. Efficient secretion of beta-lactamase (penicillin amido-beta-lactamhydrolase, EC 3.5.2.6) is observed if the complete signal sequence coding region of the alpha-amylase gene precedes the beta-lactamase structural gene. However, an incomplete alpha-amylase signal peptide lacking the six carboxy-terminal amino acid residues does not promote secretion of the fused beta-lactamase, which remains unprocessed and cell-associated.