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.
|Superclasses:||Biosynthesis → Amino Acids Biosynthesis → Proteinogenic Amino Acids Biosynthesis → L-tyrosine Biosynthesis|
The three aromatic amino acids, L-tryptophan, L-tyrosine, and L-phenylalanine, derived from the common precursor chorismate, are constituents of proteins, and precursors of many plant secondary metabolites. Two steps are required for conversion of prephenate to L-tyrosine: a dehydrogenation/decarboxylation and a transamination. Two possible routes for this conversion are known. In the route described in L-tyrosine biosynthesis I the decarboxylation occurs first, resulting in the intermediate 4-hydroxyphenylpyruvate, followed by a transamination to L-tyrosine. In the second route, described here, transamination occurs first, resulting in formation of L-arogenate, which is subsequently decarboxylated to L-tyrosine.
While the first route has been confirmed in many microorganisms, including E.coli and yeast, some other bacteria, including cyanobacteria, as well as many plants, employ the arogenate route [Stenmark74, Bonner87]. The two routes have been reported to co-exist in many microorganisms. In addition, the 4-hydroxyphenylpyruvate route cannot be completely ruled out for plants based on these facts:
1) early studies detected prephenate dehydrogenase activity in mung bean shoots [Gamborg66].
2) the Arabidopsis arogenate dehydrogenase TyrAAT2 presents a weak prephenate dehydrogenase activity [Rippert02], even though the high Km for prephenate and low specific activity of prephenate dehydrogenase reaction indicates the reaction is unlikely physiologically significant.
Two types of arogenate dehydrogenase are known, that utilze either NADP+ or NAD+. These two types are described by the pathways L-tyrosine biosynthesis II and L-tyrosine biosynthesis III, respectively.
About This Pathway
Arogenate is the branch-point and the immediate precursor for the synthesis of both tyrosine and phenylalanine. Arogenate dehydrogenase is the key enzyme channeling arogenate towards tyrosine synthesis. Its activity is strongly feedback inhibited by tyrosine.
The Arabidopsis arogenate dehydrogenase [Rippert02], as well as the enzyme from the cyanobacterium Synechocystis sp. PCC 6803 [Bonner04], are strictly NADP-dependent (see L-tyrosine biosynthesis II). The enzymes from maize [Byng81] and the actinobacterium Actinoplanes missouriensis [Hund89] are strictly NAD-dependent.
Bonner04: Bonner CA, Jensen RA, Gander JE, Keyhani NO (2004). "A core catalytic domain of the TyrA protein family: arogenate dehydrogenase from Synechocystis." Biochem J 382(Pt 1);279-91. PMID: 15171683
Rippert02: Rippert P, Matringe M (2002). "Purification and kinetic analysis of the two recombinant arogenate dehydrogenase isoforms of Arabidopsis thaliana." Eur J Biochem 269(19);4753-61. PMID: 12354106
Baldwin81: Baldwin GS, Davidson BE (1981). "A kinetic and structural comparison of chorismate mutase/prephenate dehydratase from mutant strains of Escherichia coli K 12 defective in the PheA gene." Arch Biochem Biophys 1981;211(1);66-75. PMID: 7030214
Baldwin83: Baldwin GS, Davidson BE (1983). "Kinetic studies on the mechanism of chorismate mutase/prephenate dehydratase from Escherichia coli K12." Biochim Biophys Acta 1983;742(2);374-83. PMID: 6337635
BSUB93: "Bacillus subtilis and Other Gram-Positive Bacteria: Biochemistry, Physiology, and Molecular Genetics." (1993). Editors: Sonenshein, A.L., Hoch, J.A., Losick, R. American Society For Microbiology, Washington, DC.
Chook94: Chook YM, Gray JV, Ke H, Lipscomb WN (1994). "The monofunctional chorismate mutase from Bacillus subtilis. Structure determination of chorismate mutase and its complexes with a transition state analog and prephenate, and implications for the mechanism of the enzymatic reaction." J Mol Biol 1994;240(5);476-500. PMID: 8046752
Duggleby78: Duggleby RG, Sneddon MK, Morrison JF (1978). "Chorismate mutase-prephenate dehydratase from Escherichia coli: active sites of a bifunctional enzyme." Biochemistry 1978;17(8);1548-54. PMID: 348236
Eberhard96: Eberhard J, Ehrler TT, Epple P, Felix G, Raesecke HR, Amrhein N, Schmid J (1996). "Cytosolic and plastidic chorismate mutase isozymes from Arabidopsis thaliana: molecular characterization and enzymatic properties." Plant J 10(5);815-21. PMID: 8953244
Gaines82: Gaines C G, Byng G S, Whitaker R J, Jensen R A (1982). "L-tyrosine regulation and biosynthesis via arogenate dehydrogenase in suspension-cultured cells of Nicotiana silvestris Speg. et Comes." Planta 156(3);233-240.
Gething77: Gething MJ, Davidson BE (1977). "Chorismate mutase/prephenate dehydratase from Escherichia coli K12. Effects of chemical modification on the enzymic activities and allosteric inhibition." Eur J Biochem 1977;78(1);111-7. PMID: 334530
Gething77a: Gething MJ, Davidson BE (1977). "Chorismate mutase/prephenate dehydratase from Escherichia coli K12. Modification with 5,5'-dithio-bis(2-nitrobenzoic acid)." Eur J Biochem 1977;78(1);103-10. PMID: 334529
Holding10: Holding DR, Meeley RB, Hazebroek J, Selinger D, Gruis F, Jung R, Larkins BA (2010). "Identification and characterization of the maize arogenate dehydrogenase gene family." J Exp Bot 61(13);3663-73. PMID: 20558569
Hudson83: Hudson GS, Howlett GJ, Davidson BE (1983). "The binding of tyrosine and NAD+ to chorismate mutase/prephenate dehydrogenase from Escherichia coli K12 and the effects of these ligands on the activity and self-association of the enzyme. Analysis in terms of a model." J Biol Chem 1983;258(5);3114-20. PMID: 6338013
Kane71: Kane JF, Stenmark SL, Calhoun DH, Jensen RA (1971). "Metabolic interlock. The role of the subordinate type of enzyme in the regulation of a complex pathway." J Biol Chem 1971;246(13);4308-16. PMID: 4996881
Koch72: Koch GL, Shaw DC, Gibson F (1972). "Studies on the relationship between the active sites of chorismate mutase-prephenate dehydrogenase from Escherichia coli or Aerobacter aerogenes." Biochim Biophys Acta 1972;258(3);719-30. PMID: 4552899
Lassila05: Lassila JK, Keeffe JR, Oelschlaeger P, Mayo SL (2005). "Computationally designed variants of Escherichia coli chorismate mutase show altered catalytic activity." Protein Eng Des Sel 18(4);161-3. PMID: 15820980
LutkeEversloh05: Lutke-Eversloh T, Stephanopoulos G (2005). "Feedback inhibition of chorismate mutase/prephenate dehydrogenase (TyrA) of Escherichia coli: generation and characterization of tyrosine-insensitive mutants." Appl Environ Microbiol 71(11);7224-8. PMID: 16269762
Mobley99: Mobley EM, Kunkel BN, Keith B (1999). "Identification, characterization and comparative analysis of a novel chorismate mutase gene in Arabidopsis thaliana." Gene 240(1);115-23. PMID: 10564818
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