Abstract
The substrate oxidation profiles of Sphingomonas yanoikuyae B1 biphenyl-2,3-dioxygenase and cis-biphenyl dihydrodiol dehydrogenase activities were examined with 1,2-dihydronaphthalene and various cis-diols as substrates. m-Xylene-induced cells of strain B1 oxidized 1,2-dihydronaphthalene to (-)-(1R,2S)-cis-1,2-dihydroxy-1,2-3,4-tetrahydronaphthalene as the major product (73% relative yield). Small amounts of (+)-(R)-2-hydroxy-1,2-dihydronaphthalene (15%), naphthalene (6%), and alpha-tetralone (6%) were also formed. Strain B8/36, which lacks an active cis-biphenyl dihydrodiol dehydrogenase, formed (+)-(1R,2S)-cis-1,2-dihydroxy-1,2-dihydronaphthalene (51%), in addition to (-)-(1R,2S)-cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene (44%) and (+)-(R)-2-hydroxy-1,2-dihydronaphthalene (5%). The cis-biphenyl dihydrodiol dehydrogenase of strain B1 oxidized both enantiomers of cis-1,2-dihydroxy-1,2-dihydronaphthalene, but only the (+)-(1S,2R)-enantiomers of cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene and cis-1,2-dihydroxy-3-phenylcyclohexa-3,5-diene. The results show that biphenyl dioxygenase expressed by S. yanoikuyae catalyzes dioxygenation, monooxygenation, and desaturation reactions with 1,2-dihydronaphthalene as the substrate, and cis-biphenyl dihydrodiol dehydrogenase catalyzes the enantioselective dehydrogenation of (+)-(1S,2R)-cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene and (+)-(1S,2R)-cis-1,2-dihydroxy-3-phenylcyclohexa-3,5-diene.