Cloning and characterization of three epoxide hydrolases from a marine bacterium, Erythrobacter litoralis HTCC2594.
Previously, we reported that ten strains belonging to Erythrobacter showed epoxide hydrolase (EHase) activities toward various epoxide substrates. Three genes encoding putative EHases were identified by analyzing open reading frames of Erythrobacter litoralis HTCC2594. Despite low similarities to reported EHases, the phylogenetic analysis of the three genes showed that eeh1 was similar to microsomal EHase, while eeh2 and eeh3 could be grouped with soluble EHases. The three EHase genes were cloned, and the recombinant proteins (rEEH1, rEEH2, and rEEH3) were purified. The functionality of purified proteins was proved by hydrolytic activities toward styrene oxide. EEH1 preferentially hydrolyzed (R)-styrene oxide, whereas EEH3 preferred to hydrolyze (S)-styrene oxide, representing enantioselective hydrolysis of styrene oxide. On the other hand, EEH2 could hydrolyze (R)- and (S)-styrene oxide at an equal rate. The optimal pH and temperature for the EHases occurred largely at neutral pHs and 40-55 degrees C. The substrate selectivity of rEEH1, rEEH2, and rEEH3 toward various epoxide substrates were also investigated. This is the first representation that a strict marine microorganism possessed three EHases with different enantioselectivity toward styrene oxide.
Woo
Jung-Hee
JH
Marine Biotechnology Research Centre, Korea Ocean Research and Development Institute, Ansan, PO Box 29, 425-600, South Korea.
Hwang
Young-Ok
YO
Kang
Sung Gyun
SG
Lee
Hyun Sook
HS
Cho
Jang-Cheon
JC
Kim
Sang-Jin
SJ
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis; D004851:Epoxide Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D042301:Sphingomonadaceae / Q000201:enzymology* / Q000235:genetics*
D004269:DNA, Bacterial; D004852:Epoxy Compounds; C013690:styrene oxide; D004851:Epoxide Hydrolases