Glycerol Dehydratases: Biochemical Structures, Catalytic Mechanisms, and Industrial Applications in 1,3-Propanediol Production by Naturally Occurring and Genetically Engineered Bacterial Strains

To date, two types of glycerol dehydratases have been reported: coenzyme B 12 -dependent and coenzyme B 12 -independent glycerol dehydratases. The three-dimensional structure of the former is a dimer of αβγ heterotrimer, while that of the latter is a homodimer. Their mechanisms of reaction are typically enzymatic radical catalysis. Functional radical in both the glycerol dehydratases is the adenosyl radical. However, the adenosyl radical in the former originates from coenzyme B 12 by homolytic cleavage, and that in the latter from S -adenosyl-methionine. Until some years ago, Clostridium butyricum VPI 1718 was the only microorganism known to possess B 12 -independent glycerol dehydratase, but since then, several other bacteria with this unique capability have been identified. This article focuses on the glycerol dehydratases and on 1,3-propanediol production from glycerol by naturally occurring and genetically engineered bacterial strains containing glycerol dehydratase.