title: GriC and GriD constitute a carboxylic acid reductase involved in grixazone biosynthesis in Streptomyces griseus.
abstract: In grixazone biosynthesis by Streptomyces griseus, a key intermediate 3-amino-4-hydroxybenzoic acid (3,4-AHBA) is converted to another key intermediate 3-amino-4-hydroxybenzaldehyde (3,4-AHBAL). Two genes griC and griD in the grixazone biosynthesis gene cluster were found to be responsible for this conversion, because disruption of each gene resulted in the extracellular accumulation of 3-acetylamino-4-hydroxybenzoic acid, a shunt product from 3,4-AHBA. Significant sequence similarity of GriC to AMP-binding proteins and of GriD to NAD(P)-dependent aldehyde dehydrogenases suggested that GriC and GriD constituted an ATP- and NAD(P)-dependent carboxylic acid reductase (CAR) catalyzing reduction of 3,4-AHBA to produce 3,4-AHBAL through acyl-AMP formation, as is found for the reactions catalyzed by some CARs. griG encoding a benzoate transporter homologue in the grixazone biosynthesis gene cluster was nonessential for grixazone biosynthesis but probably enhanced the membrane permeability for 3,4-AHBA. Simultaneous overexpression of griC, griD, and griG in S. griseus mutant cells deficient in an acetyltransferase responsible for N-acetylation of 3,4-AHBA led to efficient bioconversion of exogenously added 3,4-AHBA to 3,4-AHBAL. This system also turned out to be useful for reduction of some aryl carboxylates to the corresponding aryl aldehydes.
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohnishi
authors.forename: Sueharu
authors.initials: S
authors.lastname: Horinouchi
mesh_terms: D062365:Aminobenzoates / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D062385:Hydroxybenzoates; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D010078:Oxazines / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D013305:Streptomyces griseus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: C485864:1-((2-(acetylamino)-2-carboxyethyl)thio)-2-amino-3-oxo-8-carboxyl-3H-phenoxiazine; C485863:1-((2-(acetylamino)-2-carboxyethyl)thio)-2-amino-3-oxo-8-formyl-3H-phenoxiazine; D062365:Aminobenzoates; D004269:DNA, Bacterial; D062385:Hydroxybenzoates; D010078:Oxazines; C110924:3-amino-4-hydroxybenzoic acid; D010088:Oxidoreductases; C019825:carboxylic acid reductase