MetaCyc Pathway: L-homomethionine biosynthesis
Inferred from experiment

Pathway diagram: L-homomethionine biosynthesis

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: L-methionine chain elongation pathway

Superclasses: BiosynthesisAmino Acids BiosynthesisOther 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.

Citations: [Kroymann01 , Wittstock02]

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

Wittstock02: Wittstock U, Halkier BA (2002). "Glucosinolate research in the Arabidopsis era." Trends Plant Sci 2002;7(6);263-70. PMID: 12049923

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

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

Junk02: Junk DJ, Mourad GS (2002). "Isolation and expression analysis of the isopropylmalate synthase gene family of Arabidopsis thaliana." J Exp Bot 53(379);2453-4. PMID: 12432038

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

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

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

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Wed May 4, 2016, biocyc13.