title: A single-nucleotide mutation in a gene encoding S-adenosylmethionine synthetase is associated with methionine over-accumulation phenotype in Arabidopsis thaliana.
abstract: Met-overaccumulating mutants provide a powerful genetic tool for examining both the regulation of the Met biosynthetic pathway and in vivo developmental responses of gene expression to altered Met levels. We have previously reported the identification of two Arabidopsis thaliana Met over-accumulation (mto) mutants, mto1-1 and mto2-1, that carry mutations in the genes encoding cystathionine gamma-synthase (CGS) and threonine synthase (TS), respectively. A third mutant, mto3-1, has recently been reported to carry a mutation in the gene encoding S-adenosylmethionine synthetase 3 (SAMS3). Here, we report the isolation of a new ethionine-resistant A. thaliana mutant that over-accumulates soluble Met approximately 20-fold in young rosettes. The causal mutation was determined to be a single, recessive mutation that was mapped to chromosome 3. Sequence analysis identified a single nucleotide change in the gene encoding SAMS3 that was distinct from the mto3-1 mutation and altered the amino acid sequence of the enzyme active site. This mutation was therefore referred to as mto3-2. Although Met over-accumulation in the mto3-2 mutant was similar to that in the mto2-1 mutant, CGS mRNA levels did not respond to the mto3-2 mutation and were similar to that in equivalent wild-type plants.
authors.affiliation: Laboratory of Molecular Biology, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Japan.
authors.forename: Derek B
authors.initials: DB
authors.lastname: Goto
authors.forename: Makoto
authors.initials: M
authors.lastname: Ogi
authors.forename: Fumiko
authors.initials: F
authors.lastname: Kijima
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kumagai
authors.forename: Folkert
authors.initials: F
authors.lastname: van Werven
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Onouchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naito
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D018744:DNA, Plant / Q000235:genetics; D005001:Ethionine / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008715:Methionine / Q000378:metabolism*; D008716:Methionine Adenosyltransferase / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D017354:Point Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D012333:RNA, Messenger; D008715:Methionine; D008716:Methionine Adenosyltransferase; D005001:Ethionine