Biochemical characterization and biosynthetic application of a halohydrin dehalogenase from Tistrella mobilis ZJB1405

• Cloning and expression of a novel HHDH from Tistrella mobilis ZJB1405.
• HHDHTm exhibits higher activities toward halohydrins under more alkaline condition.
• HHDHTm shows unusual enantioselectivities for the conversion of prochiral halohydrins.
• The preparation of (S)-ECH from prochiral 1,3-DCP with more than 50% yield.
• Biocatalysis of 100 g/L (S)-CHBE to (R)-HN with 89% recovered yield and >99% ee.

A novel halohydrin dehalogenase (HHDHTm) has been identified in Tistrella mobilis ZJB1405 and subsequently cloned and over-expressed in Escherichia coli. HHDHTm shares low similarity (less than 38%), and has different biochemical catalytic characteristics from other HHDHs. The purified HHDHTm displays maximum enzymatic activity toward 1,3-dichloro-2-propanol (DCP) at the more alkaline pH, 45 °C. HHDHTm was stable up to 55 °C and approximately 60% of residual activity retained at 60 °C for 1 h. HHDHTm shows higher activities toward halohydrins with modest enantioselectivities compared with other reported HHDHs. Interesting, (S)-epichlorohydrin (ECH) was enantioselectively biotransformed from the prochiral 1,3-DCP with about 75% yield. Moreover, 100 g/L ethyl (S)-4-chloro-3-hydroxybutyrate (CHBE) can be converted to ethyl (R)-4-cyano-3-hydroxybutyrate (HN) with >99% ee and 89% isolated recovery by the recombinant HHDHTm. Therefore, HHDHTm is a promising biocatalyst for (S)-ECH and (R)-HN production.

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