A gene controlling variation in Arabidopsis glucosinolate composition is part of the methionine chain elongation pathway.
Arabidopsis and other Brassicaceae produce an enormous diversity of aliphatic glucosinolates, a group of methionine (Met)-derived plant secondary compounds containing a beta-thio-glucose moiety, a sulfonated oxime, and a variable side chain. We fine-scale mapped GSL-ELONG, a locus controlling variation in the side-chain length of aliphatic glucosinolates. Within this locus, a polymorphic gene was identified that determines whether Met is extended predominantly by either one or by two methylene groups to produce aliphatic glucosinolates with either three- or four-carbon side chains. Two allelic mutants deficient in four-carbon side-chain glucosinolates were shown to contain independent missense mutations within this gene. In cell-free enzyme assays, a heterologously expressed cDNA from this locus was capable of condensing 2-oxo-4-methylthiobutanoic acid with acetyl-coenzyme A, the initial reaction in Met chain elongation. The gene methylthioalkylmalate synthase1 (MAM1) is a member of a gene family sharing approximately 60% amino acid sequence similarity with 2-isopropylmalate synthase, an enzyme of leucine biosynthesis that condenses 2-oxo-3-methylbutanoate with acetyl-coenzyme A.
Kroymann
J
J
Department of Genetics and Evolution, Max Planck Institute for Chemical Ecology, Carl-Zeiss-Promenade 10, 07745 Jena, Germany.
Textor
S
S
Tokuhisa
J G
JG
Falk
K L
KL
Bartram
S
S
Gershenzon
J
J
Mitchell-Olds
T
T
D015079:2-Isopropylmalate Synthase / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D005091:Exons; D018506:Gene Expression Regulation, Plant; D005961:Glucosinolates / Q000235:genetics / Q000378:metabolism*; D007438:Introns; D008715:Methionine / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D007652:Oxo-Acid-Lyases / Q000235:genetics; D010441:Peptide Chain Elongation, Translational
D005961:Glucosinolates; D000105:Acetyl Coenzyme A; D008715:Methionine; D015079:2-Isopropylmalate Synthase; D007652:Oxo-Acid-Lyases; C446529:methylthioalkylmalate synthase 1