title: A bacterial aromatic aldehyde dehydrogenase critical for the efficient catabolism of syringaldehyde.
abstract: Vanillin and syringaldehyde obtained from lignin are essential intermediates for the production of basic chemicals using microbial cell factories. However, in contrast to vanillin, the microbial conversion of syringaldehyde is poorly understood. Here, we identified an aromatic aldehyde dehydrogenase (ALDH) gene responsible for syringaldehyde catabolism from 20 putative ALDH genes of Sphingobium sp. strain SYK-6. All these genes were expressed in Escherichia coli, and nine gene products, including previously characterized BzaA, BzaB, and vanillin dehydrogenase (LigV), exhibited oxidation activities for syringaldehyde to produce syringate. Among these genes, SLG_28320 (desV) and ligV were most highly and constitutively transcribed in the SYK-6 cells. Disruption of desV in SYK-6 resulted in a significant reduction in growth on syringaldehyde and in syringaldehyde oxidation activity. Furthermore, a desV ligV double mutant almost completely lost its ability to grow on syringaldehyde. Purified DesV showed similar kcat/Kmvalues for syringaldehyde (2100 s-1·mM-1) and vanillin (1700 s-1·mM-1), whereas LigV substantially preferred vanillin (8800 s-1·mM-1) over syringaldehyde (1.4 s-1·mM-1). These results clearly demonstrate that desV plays a major role in syringaldehyde catabolism. Phylogenetic analyses showed that DesV-like ALDHs formed a distinct phylogenetic cluster separated from the vanillin dehydrogenase cluster.
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Kamimura
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Goto
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kasai
authors.affiliation: Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Otsuka
authors.affiliation: Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-0880, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Katayama
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Department of Bioengineering, Nagaoka University of Technology, Nagaoka, Niigata 940-2188, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Masai
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics; D001547:Benzaldehydes / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D008660:Metabolism / Q000235:genetics; D005810:Multigene Family / Q000235:genetics; D010802:Phylogeny; D042301:Sphingomonadaceae / Q000235:genetics / Q000378:metabolism*
chemical_list: D001547:Benzaldehydes; C069665:syringaldehyde; C100058:vanillin; D000445:Aldehyde Oxidoreductases; C105452:vanillin dehydrogenase; D000444:Aldehyde Dehydrogenase