Characterization of hydroxy fatty acid dehydrogenase involved in polyunsaturated fatty acid saturation metabolism in Lactobacillus plantarum AKU 1009a

Abstract

Hydroxy fatty acid dehydrogenase, which is involved in polyunsaturated fatty acid saturation metabolism in Lactobacillus plantarum AKU 1009a, was cloned, expressed, purified, and characterized. The enzyme preferentially catalyzed NADH-dependent hydrogenation of oxo fatty acids over NAD[+]-dependent dehydrogenation of hydroxy fatty acids. In the dehydrogenation reaction, fatty acids with an internal hydroxy group such as 10-hydroxy-cis-12-octadecenoic acid, 12-hydroxy-cis-9-octadecenoic acid, and 13-hydroxy-cis-9-octadecenoic acid served as better substrates than those with α- or β-hydroxy groups such as 3-hydroxyoctadecanoic acid or 2-hydroxyeicosanoic acid. The apparent K[m] value for 10-hydroxy-cis-12-octadecenoic acid (HYA) was estimated to be 38 μM with a k[cat] of 7.6 × 10[−3] s[−1]. The apparent K[m] value for 10-oxo-cis-12-octadecenoic acid (KetoA) was estimated to be 1.8 μM with a k[cat] of 5.7 × 10[−1] s[−1]. In the hydrogenation reaction of KetoA, both (R)[-] and (S)-HYA were generated, indicating that the enzyme has low stereoselectivity. This is the first report of a dehydrogenase with a preference for fatty acids with an internal hydroxy group.