Expression and Characterization of a Novel 1,3-Propanediol Dehydrogenase from Lactobacillus brevis.

ABSTRACT

1,3-Propanediol dehydrogenase (PDOR) is important in the biosynthesis of 1,3-propanediol. In the present study, the dhaT gene encoding PDOR was cloned from Lactobacillus brevis 6239 and expressed in Escherichia coli for the first time. Sequence analysis revealed that PDOR containing two Fe(2+)-binding motifs and a cofactor motif belongs to the type III alcohol dehydrogenase. The purified recombinant PDOR exhibited a single band of 42 kDa according to SDS-PAGE. Optimal temperatures and pH values of this dehydrogenase are 37 °C, 7.5 for reduction and 25 °C, 9.5 for oxidation, respectively. We found that PDOR was more stable in acid buffer than in alkaline condition, and 60 % of its relative activity still remained after a 2-h incubation at 37 °C. The activity of PDOR can be enhanced in the presence of Mn(2+) or Fe(2+) iron and inhibited by EDTA or PMSF by different degrees. The K m and V max of this dehydrogenase are 1.25 mM, 64.02 µM min(-1) mg(-1) for propionaldehyde and 2.26 mM, 35.05 µM min(-1) mg(-1) for 1,3-PD, respectively. Substrate specificity analysis showed that PDOR has a broad range of substrate specificities. The modeling superposition indicated that the structural differences may account for the diversity of PDORs' properties. Thus, our PDOR is a potential candidate for facilitating the 1,3-PD biosynthesis.