Expression in Escherichia coli of the Bacillus subtilis neutral protease gene (NPRE) lacking its ribosome binding site

Bacillus subtilis neutral protease (NprE) is first produced as a precursor, pre-pro-NprE, which consists of a signal peptide or prepeptide for secretion (27 amino acid residues) and a pro-peptide (194 amino acid residues) between the signal peptide and the mature protease. While the wildtype nprE gene could not be maintained in Escherichia coli, we have been able to show that expression and secretion of the neutral protease can be achieved from the nprE gene when its ribosome binding site (RBS) is removed. The results suggest that the failure to observe expression of the wildtype nprE gene is due to the lytic effect of the nprE gene product on E. coli host cells and that translation initiation in E. coli can be achieved even in the absence of a classical ribosome binding site.