The osmoregulation proB and proA genes from Bacillus subtilis 93151 are overlapping genes, which encode two proteins ProB and ProA. A restriction enzyme site was inserted in the overlapping region of proB and proA genes from a salt-tolerant mutant of B. subtilis 93151, and a fusion gene was constructed by cloning proB and proA genes respectively. SDS-PAGE analysis showed that a novel protein with molecular mass of 85 kD was observed. When expressed in E.coli, enhanced intracellular concentrations of free proline and osmotolerance of the strain carrying the fusion gene were observed, compared with the control host cell harbouring a plasmid encoding the separate ProB and ProA.
Acta Microbiologica Sinica