Physiological roles of the beta-substituted alanine synthase gene family in Arabidopsis

Plant Physiol. 2008 Jan;146(1):310-20. doi: 10.1104/pp.107.106831. Epub 2007 Nov 16.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidohydrolases / chemistry
  • Amidohydrolases / deficiency
  • Amidohydrolases / genetics*
  • Amidohydrolases / metabolism*
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Gene Deletion
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant
  • Multigene Family*
  • Phenotype
  • Sulfhydryl Compounds / metabolism

Substances

  • Sulfhydryl Compounds
  • Amidohydrolases
  • beta-ureidopropionase