Bacillus amyloliquefaciens possesses a second type I signal peptidase with extensive sequence similarity to other Bacillus SPases.

A second sipS2(BA) gene was PCR cloned from Bacillus amyloliquefaciens. The deduced aa sequence is similar to those of the SPases of B. subtilis, B. amyloliquefaciens, and B. licheniformis and the domain structure of the gene has been preserved. A low level of monocistronic gene transcription could be shown using Northern analysis. The sipS2(BA) gene was mapped to a region downstream of an E. coli fruA gene homologue and shown to express a 21 kDa protein in Escherichia coli.