Cloning and characterization of a gene from Bacillus stearothermophilus var. non-diastaticus encoding a glycerol dehydrogenase

A 4.1-kb EcoRI fragment which includes the gene ( gldA) encoding a glycerol dehydrogenase (GIDH; EC 1.1.1.6; glycerol:NAD oxidoreductase) from Bacillus stearothermophilus var. non-diastaticus has been cloned by virtue of its ability to restore glycerol utilisation to Escherichia coli glycerol kinase ( glpK) and glycerol-3-phosphate dehydrogenase ( glpD) mutants. Sequencing suggests that the gldA gene is likely to be monocistronic and encodes a protein of 39450 Da. The deduced amino acid composition and sequence of G1DH reveals that the protein is extremely similar to a characterized metal-dependent NAD-dependent G1DH from B. stearothermophilis RS93. The enzyme has limited homology to the iron-activated alcohol dehydrogenase of Zymomonas mobilis and the butanol dehydrogenase of Clostridium acetobutylicum.