Recognition sequence specificity of signal peptidase I and the role of signal peptide in secretion of protein in Bacillus subtilis.

By recombinant DNA technology, the N-terminal of the beta-protein encoding region of plasmid pUB110 is fused with the structure gene of alpha-amylase from Bacillus licheniformis. This gene fusion is called beta Amy. It is able to transcribe and translate in phase. Protein fusion can be secreted into the medium mediated by beta-signal peptide. The efficiency of secretion is about 10% of the synthesized pre-alpha-amylase. By comparing the secretion capacities and analysing the restriction sites on beta-Amy genes and the molecular weights of the mature alpha-amylase secreted by B. subtilis harbouring different plasmids, it is indicated in vivo that the recognition and cleavage sequence for signal peptidase I of B. subtilis is Ala-Ala-Ala Ala. The results also indicate that the secretion of the alpha-amylase in B. subtilis is in accordance with the post-translational transportation mode.