This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: methionine chain elongation pathway
|Superclasses:||Biosynthesis → Amino Acids Biosynthesis → Individual Amino Acids Biosynthesis → Other Amino Acid Biosynthesis|
Some taxa known to possess this pathway include : Arabidopsis thaliana col
Expected Taxonomic Range: Brassicales
Homomethionine is a non-protein amino acid. Homomethionine is synthesized from methionine via chain elongation. Transamination of methionine first forms a 2-oxo acid. The 2-oxo acid is then extended by one methyl group by a condensation reaction, an isomerization reaction, and a oxidative decarboxylation reaction. The newly formed 2-oxo acid can be transaminated to homomethionine or undergo further cycles of condensation, isomerization and oxidative decarboxylation to form di, tri, tetra, penta, and hexahomomethionines. Mono, di, tri, tetra, penta, and hexahomomethionines are precursors for aliphatic glucosinolates biosynthesis in Arabidopsis.
The cytosolic recycled methionine (S-adenosyl-L-methionine cycle II), not the plastid-located de novo synthesized methionine, is believed to be the substrate for methionine chain elongation and glucosinolate biosynthesis [Schuster06]. First, the first enzyme in the chain elongation pathway, methionine-oxo-acid transaminase (AT-BCAT4), is cytosolic. Second, the gene expressions of AT-BCAT4 and the two cytosolic methionine synthase, involved in the SAM cycle, are strongly co-regulated.
Unification Links: AraCyc:PWY-1186
Revised 21-Apr-2010 by Zhang P
Kroymann01: Kroymann J, Textor S, Tokuhisa JG, Falk KL, Bartram S, Gershenzon J, Mitchell-Olds T (2001). "A gene controlling variation in Arabidopsis glucosinolate composition is part of the methionine chain elongation pathway." Plant Physiol 127(3);1077-88. PMID: 11706188
Schuster06: Schuster J, Knill T, Reichelt M, Gershenzon J, Binder S (2006). "Branched-chain aminotransferase4 is part of the chain elongation pathway in the biosynthesis of methionine-derived glucosinolates in Arabidopsis." Plant Cell 18(10);2664-79. PMID: 17056707
Berger03: Berger BJ, English S, Chan G, Knodel MH (2003). "Methionine regeneration and aminotransferases in Bacillus subtilis, Bacillus cereus, and Bacillus anthracis." J Bacteriol 185(8);2418-31. PMID: 12670965
Dolzan04: Dolzan M, Johansson K, Roig-Zamboni V, Campanacci V, Tegoni M, Schneider G, Cambillau C (2004). "Crystal structure and reactivity of YbdL from Escherichia coli identify a methionine aminotransferase function." FEBS Lett 571(1-3);141-6. PMID: 15280032
Heilbronn99: Heilbronn J, Wilson J, Berger BJ (1999). "Tyrosine aminotransferase catalyzes the final step of methionine recycling in Klebsiella pneumoniae." J Bacteriol 1999;181(6);1739-47. PMID: 10074065
Knill08: Knill T, Schuster J, Reichelt M, Gershenzon J, Binder S (2008). "Arabidopsis branched-chain aminotransferase 3 functions in both amino acid and glucosinolate biosynthesis." Plant Physiol 146(3);1028-39. PMID: 18162591
Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216
Textor04: Textor S, Bartram S, Kroymann J, Falk KL, Hick A, Pickett JA, Gershenzon J (2004). "Biosynthesis of methionine-derived glucosinolates in Arabidopsis thaliana: recombinant expression and characterization of methylthioalkylmalate synthase, the condensing enzyme of the chain-elongation cycle." Planta 218(6);1026-35. PMID: 14740211
Textor07: Textor S, de Kraker JW, Hause B, Gershenzon J, Tokuhisa JG (2007). "MAM3 catalyzes the formation of all aliphatic glucosinolate chain lengths in Arabidopsis." Plant Physiol 144(1);60-71. PMID: 17369439
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