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 → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis → Polyprenyl Biosynthesis|
Some taxa known to possess this pathway include : Campylobacter jejuni , Capnocytophaga gingivalis , Capnocytophaga ochracea , Capnocytophaga sputigena , Desulfovibrio desulfuricans , Desulfovibrio gigas , Desulfovibrio vulgaris , Haemophilus parainfluenzae , Helicobacter pylori , Micrococcus luteus B-P 26 , Saccharomyces cerevisiae , Staphylococcus lentus , Staphylococcus sciuri sciuri
In this pathway multiple units of isopentenyl diphosphate (IPP) undergo a series of polymerizations to form a polyisoprenoid chain.
Additional isoprenoid units are added to a maximal length that is determined by the specific enzyme. Most organisms generate polyprenyl chains of predominantly one length. Once completed, the polyprenyl chain is incorporated into other molecules, such as quinones. The enzyme that attaches the polyprenyl chain to the quinone precursor molecule does not have a preference towards a particular length. Thus, the length of the polyprenyl chain in the mature quinone molecule is determined by the predominant polyprenyl diphosphate synthase enzyme of the organism.
In most organisms there is one type of a predominant quinone, with a specific polyprenyl chain length. However, most organisms also have minor amounts of quinones with a different polyprenyl chain length. Quinones that contain a chain of 6 isoprenyl units are not common in bacteria, although they are quite common in yeast. Among the bacteria whose primary quinone contains a 6-isoprenyl chain are members of the Gram-negative genera Helicobacter pylori [Marcelli96], Capnocytophaga and Desulfovibrio, as well as some members of the Gram-positive genus Staphylococcus. For a review detailing the polyprenyl chain length distribution in different bacteria, see [Collins81].
In Saccharomyces cerevisiae the initial addition of two isoprenyl units to form (2E,6E)-farnesyl diphosphate is catalyzed by farnesyl diphosphate synthase, encoded by FPP1. An additional unit is added by farnesyltranstransferase (encoded by BTS1), resulting in formation of geranylgeranyl diphosphate. The last enzyme in this pathway is hexaprenyl diphosphate synthase (encoded by COQ1), which adds additional isoprenoid units to a maximal length of 6 units. When yeast COQ1 mutants are complemented with homologs from other organisms, ubiquinone biosynthesis is restored, but the tail lenghth of the quinone depends on the source of the enzyme [Okada97a].
Marcelli96: Marcelli SW, Chang HT, Chapman T, Chalk PA, Miles RJ, Poole RK (1996). "The respiratory chain of Helicobacter pylori: identification of cytochromes and the effects of oxygen on cytochrome and menaquinone levels." FEMS Microbiol Lett 138(1);59-64. PMID: 8674971
Okada97a: Okada K, Kamiya Y, Zhu X, Suzuki K, Tanaka K, Nakagawa T, Matsuda H, Kawamukai M (1997). "Cloning of the sdsA gene encoding solanesyl diphosphate synthase from Rhodobacter capsulatus and its functional expression in Escherichia coli and Saccharomyces cerevisiae." J Bacteriol 179(19);5992-8. PMID: 9324242
Ashby90: Ashby MN, Edwards PA (1990). "Elucidation of the deficiency in two yeast coenzyme Q mutants. Characterization of the structural gene encoding hexaprenyl pyrophosphate synthetase." J Biol Chem 265(22);13157-64. PMID: 2198286
Shimizu98: Shimizu N, Koyama T, Ogura K (1998). "Molecular cloning, expression, and characterization of the genes encoding the two essential protein components of Micrococcus luteus B-P 26 hexaprenyl diphosphate synthase." J Bacteriol 180(6);1578-81. PMID: 9515931
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