Characterization of signal-sequence-coding regions selected from the Bacillus subtilis chromosome.

Signal-sequence-coding regions for protein export were selected from chromosomal Bacillus subtilis DNA. The number of different signals obtained was higher than expected on the basis of known exported proteins in B. subtilis. Most of the selected regions showed the characteristics of typical signal sequences, including a basic N-terminal region followed by a hydrophobic core and a potential signal-peptidase cleavage site. The signal-coding regions were functionally interchangeable between the B. licheniformis alpha-amylase and Escherichia coli TEM beta-lactamase genes. In addition to the signal-sequence-coding regions, the nature of the host cells, and the mature parts of the reporter proteins contributed to the amounts of protein secreted.