title: Functional characterization of rose phenylacetaldehyde reductase (PAR), an enzyme involved in the biosynthesis of the scent compound 2-phenylethanol.
abstract: 2-Phenylethanol (2PE) is a prominent scent compound released from flowers of Damask roses (Rosa×damascena) and some hybrid roses (Rosa 'Hoh-Jun' and Rosa 'Yves Piaget'). 2PE is biosynthesized from l-phenylalanine (l-Phe) via the intermediate phenylacetaldehyde (PAld) by two key enzymes, aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). Here we describe substrate specificity and cofactor preference in addition to molecular characterization of rose-PAR and recombinant PAR from R.×damascena. The deduced amino acid sequence of the full-length cDNA encoded a protein exhibiting 77% and 75% identity with Solanum lycopersicum PAR1 and 2, respectively. The transcripts of PAR were higher in petals than calyxes and leaves and peaking at the unfurling stage 4. Recombinant PAR and rose-PAR catalyzed reduction of PAld to 2PE using NADPH as the preferred cofactor. Reductase activity of rose-PAR and recombinant PAR were higher for aromatic and aliphatic aldehydes than for keto-carbonyl groups. Both PARs showed that (S)-[4-(2)H] NADPH was preferentially used over the (R)-[4-(2)H] isomer to give [1-(2)H]-2PE from PAld, indicating that PAR can be classified as short-chain dehydrogenase reductase (SDR).
authors.affiliation: Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, Japan.
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Chen
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Miwa
authors.initials: M
authors.lastname: Sakai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirata
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Asai
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohnishi
authors.forename: Susanne
authors.initials: S
authors.lastname: Baldermann
authors.forename: Naoharu
authors.initials: N
authors.lastname: Watanabe
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D010626:Phenylethyl Alcohol / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D027826:Rosa / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D010940:Plant Proteins; D000429:Alcohol Oxidoreductases; C110191:phenylacetaldehyde reductase; D010626:Phenylethyl Alcohol