title: Membrane-associated glucose-methanol-choline oxidoreductase family enzymes PhcC and PhcD are essential for enantioselective catabolism of dehydrodiconiferyl alcohol.
abstract: Sphingobium sp. strain SYK-6 is able to degrade various lignin-derived biaryls, including a phenylcoumaran-type compound, dehydrodiconiferyl alcohol (DCA). In SYK-6 cells, the alcohol group of the B-ring side chain of DCA is initially oxidized to the carboxyl group to generate 3-(2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-2,3-dihydrobenzofuran-5-yl) acrylic acid (DCA-C). Next, the alcohol group of the A-ring side chain of DCA-C is oxidized to the carboxyl group, and then the resulting metabolite is catabolized through vanillin and 5-formylferulate. In this study, the genes involved in the conversion of DCA-C were identified and characterized. The DCA-C oxidation activities in SYK-6 were enhanced in the presence of flavin adenine dinucleotide and an artificial electron acceptor and were induced ca. 1.6-fold when the cells were grown with DCA. Based on these observations, SLG_09480 (phcC) and SLG_09500 (phcD), encoding glucose-methanol-choline oxidoreductase family proteins, were presumed to encode DCA-C oxidases. Analyses of phcC and phcD mutants indicated that PhcC and PhcD are essential for the conversion of (+)-DCA-C and (-)-DCA-C, respectively. When phcC and phcD were expressed in SYK-6 and Escherichia coli, the gene products were mainly observed in their membrane fractions. The membrane fractions of E. coli that expressed phcC and phcD catalyzed the specific conversion of DCA-C into the corresponding carboxyl derivatives. In the oxidation of DCA-C, PhcC and PhcD effectively utilized ubiquinone derivatives as electron acceptors. Furthermore, the transcription of a putative cytochrome c gene was significantly induced in SYK-6 grown with DCA. The DCA-C oxidation catalyzed by membrane-associated PhcC and PhcD appears to be coupled to the respiratory chain.
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Hirose
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Kamimura
authors.affiliation: Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan.
authors.forename: Shojiro
authors.initials: S
authors.lastname: Hishiyama
authors.affiliation: Department of Environmental Engineering and Green Technology, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hara
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Araki
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kasai
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kajita
authors.affiliation: College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Katayama
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata, Japan emasai@vos.nagaokaut.ac.jp.
authors.forename: Eiji
authors.initials: E
authors.lastname: Masai
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D010636:Phenols / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D042301:Sphingomonadaceae / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D010636:Phenols; C080686:dehydrodiconiferyl alcohol