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: plastoquinone biosynthesis I, plastoquinone-9 biosynthesis I, plastoquinol biosynthesis I
|Superclasses:||Biosynthesis → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis → Quinol and Quinone Biosynthesis → Plastoquinol Biosynthesis|
Plastoquinones (PQ) are benzoquinone electron carriers that can function as acceptor/donor for either one or two electrons. They are analogs of ubiquinones (Coenzyme Q), with two methyl groups substituting the methoxy groups found in Q. The fully reduced form is called a plastoquinol.
Plastoquinones are found in the chloroplasts of higher plants, red, brown and green algae, and in cyanobacteria, and are important members of the photosynthetic electron transfer chain, where they carry electrons from photosystem II to the cytochrome b6f complex. In fact, it has been shown that in cyanobacteria essentially all electron transport through unbound quinones proceeds via PQ in cyanobacterial thylakoids. Apart from PQ the only quinone found in thylakoids is vitamin K1, which is associated with PS I [Vermaas01].
Plastoquinones also serve as cofactors involved in the desaturation of phytoene in the synthesis of carotenoids (see trans-lycopene biosynthesis II (plants)).
Plastoquinone was isolated originally in 1946 from alfalfa, but was not identified at the time. It was rediscovered in 1959 and its structure was described in the same year (see [Collins81]).
About This Pathway
The pathway for the biosynthesis of plastoquinone in plants starts with 4-hydroxyphenylpyruvate, which is converted to homogentisate. homogentisate is a branching point in the formation of plastoquinones and tocopherols. The committed step in plastoquinone biosynthesis is condensation of homogentisate and all-trans-nonaprenyl diphosphate, which is catalyzed by homogentisate solanyltransferase. A different enzyme ( homogentisate phytyltransferase) catalyzes the condensation of homogentisate with phytyl diphosphate, the committed step for biosynthesis of tocopherols (see vitamin E biosynthesis (tocopherols)).
The plastoquinone biosynthesis in cyanobacteria is different than that of plants (see plastoquinol-9 biosynthesis II).
Superpathways: superpathway of plastoquinol biosynthesis
Variants: plastoquinol-9 biosynthesis II
Unification Links: AraCyc:PWY-1581
Cahoon03: Cahoon EB, Hall SE, Ripp KG, Ganzke TS, Hitz WD, Coughlan SJ (2003). "Metabolic redesign of vitamin E biosynthesis in plants for tocotrienol production and increased antioxidant content." Nat Biotechnol 21(9);1082-7. PMID: 12897790
Cheng03: Cheng Z, Sattler S, Maeda H, Sakuragi Y, Bryant DA, DellaPenna D (2003). "Highly divergent methyltransferases catalyze a conserved reaction in tocopherol and plastoquinone synthesis in cyanobacteria and photosynthetic eukaryotes." Plant Cell 15(10);2343-56. PMID: 14508009
Horvath: Horvath G, Wessjohann L, Bigirimana J, Monica H, Jansen M, Guisez Y, Caubergs R, Horemans N "Accumulation of tocopherols and tocotrienols during seed development of grape (Vitis vinifera L. cv. Albert Lavallee)." Plant Physiol Biochem 44(11-12);724-31. PMID: 17110122
Sadre06: Sadre R, Gruber J, Frentzen M (2006). "Characterization of homogentisate prenyltransferases involved in plastoquinone-9 and tocochromanol biosynthesis." FEBS Lett 580(22);5357-62. PMID: 16989822
Sadre10: Sadre R, Frentzen M, Saeed M, Hawkes T (2010). "Catalytic reactions of the homogentisate prenyl transferase involved in plastoquinone-9 biosynthesis." J Biol Chem 285(24);18191-8. PMID: 20400515
Soll85: Soll J, Schultz G, Joyard J, Douce R, Block MA (1985). "Localization and synthesis of prenylquinones in isolated outer and inner envelope membranes from spinach chloroplasts." Arch Biochem Biophys 238(1);290-9. PMID: 3985624
Brownlee04: Brownlee JM, Johnson-Winters K, Harrison DH, Moran GR (2004). "Structure of the ferrous form of (4-hydroxyphenyl)pyruvate dioxygenase from Streptomyces avermitilis in complex with the therapeutic herbicide, NTBC." Biochemistry 43(21);6370-7. PMID: 15157070
Dahnhardt02: Dahnhardt D, Falk J, Appel J, van der Kooij TA, Schulz-Friedrich R, Krupinska K (2002). "The hydroxyphenylpyruvate dioxygenase from Synechocystis sp. PCC 6803 is not required for plastoquinone biosynthesis." FEBS Lett 523(1-3);177-81. PMID: 12123828
Garcia00a: Garcia I, Job D, Matringe M (2000). "Inhibition of p-hydroxyphenylpyruvate dioxygenase by the diketonitrile of isoxaflutole: a case of half-site reactivity." Biochemistry 39(25);7501-7. PMID: 10858299
Garcia99: Garcia I, Rodgers M, Pepin R, Hsieh TF, Matringe M (1999). "Characterization and subcellular compartmentation of recombinant 4-hydroxyphenylpyruvate dioxygenase from Arabidopsis in transgenic tobacco." Plant Physiol 119(4);1507-16. PMID: 10198110
Gunsior04: Gunsior M, Ravel J, Challis GL, Townsend CA (2004). "Engineering p-hydroxyphenylpyruvate dioxygenase to a p-hydroxymandelate synthase and evidence for the proposed benzene oxide intermediate in homogentisate formation." Biochemistry 43(3);663-74. PMID: 14730970
Motohashi03: Motohashi R, Ito T, Kobayashi M, Taji T, Nagata N, Asami T, Yoshida S, Yamaguchi-Shinozaki K, Shinozaki K (2003). "Functional analysis of the 37 kDa inner envelope membrane polypeptide in chloroplast biogenesis using a Ds-tagged Arabidopsis pale-green mutant." Plant J 34(5);719-31. PMID: 12787252
Norris98: Norris SR, Shen X, DellaPenna D (1998). "Complementation of the Arabidopsis pds1 mutation with the gene encoding p-hydroxyphenylpyruvate dioxygenase." Plant Physiol 117(4);1317-23. PMID: 9701587
Shintani02: Shintani DK, Cheng Z, DellaPenna D (2002). "The role of 2-methyl-6-phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803." FEBS Lett 511(1-3);1-5. PMID: 11821038
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