title: Physiological roles of the beta-substituted alanine synthase gene family in Arabidopsis.
abstract: The beta-substituted alanine (Ala) synthase (Bsas) family in the large superfamily of pyridoxal 5'-phosphate-dependent enzymes comprises cysteine (Cys) synthase (CSase) [O-acetyl-serine (thiol) lyase] and beta-cyano-Ala synthase (CASase) in plants. Nine genomic sequences encode putative Bsas proteins in Arabidopsis thaliana. The physiological roles of these Bsas isoforms in vivo were investigated by the characterization of T-DNA insertion mutants. Analyses of gene expression, activities of CSase and CASase, and levels of Cys and glutathione in the bsas mutants indicated that cytosolic Bsas1;1, plastidic Bsas2;1, and mitochondrial Bsas2;2 play major roles in Cys biosynthesis. Cytosolic Bsas1;1 has the most dominant contribution both in leaf and root, and mitochondrial Bsas2;2 plays a significant role in root. Mitochondrial Bsas3;1 is a genuine CASase. Nontargeted metabolome analyses of knockout mutants were carried out by a combination of gas chromatography time-of-flight mass spectrometry and capillary electrophoresis time-of-flight mass spectrometry. The level of gamma-glutamyl-beta-cyano-Ala decreased in the mutant bsas3;1, indicating the crucial role of Bsas3;1 in beta-cyano-Ala metabolism in vivo.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Watanabe
authors.forename: Miyako
authors.initials: M
authors.lastname: Kusano
authors.forename: Akira
authors.initials: A
authors.lastname: Oikawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukushima
authors.forename: Masaaki
authors.initials: M
authors.lastname: Noji
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005810:Multigene Family; D010641:Phenotype; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D013438:Sulfhydryl Compounds; D000581:Amidohydrolases; C021590:beta-ureidopropionase