Levansucrase: a tool to study protein secretion in Bacillus subtilis.

The Bacillus amyloliquefaciens levansucrase gene (sacB[BamP]) was engineered in such a way that a heterologous gene could be inserted between the second and third codon of the mature levansucrase. Extracellular levansucrase activity was detected only when the heterologous protein was secreted into the growth medium. A positive selection system to isolate suppressors of signal sequence mutants in Bacillus subtilis has been developed based on the secretion of levansucrase.