Improved translational efficiency of subtilisin YaB gene with different initiation codons in Bacillus subtilis and alkalophilic Bacillus YaB.

The ale gene specifying the subtilisin YaB produced by alkalophilic Bacillus YaB, has an unusual start codon UUG. Changing this codon to AUG and GUG increased expression of the ale gene in B. subtilis DB104 and in an ale deficient mutant strain YaB-DEC4. The relative translational efficiency order of the three initiation codons is AUG > GUG > UUG in B. subtilis DB104 and in YaB-DEC4. These data suggest that the preferred initiation codon is AUG for ale gene expression in Bacillus.