Membrane-associated reactions in ubiquinone biosynthesis in Escherichia coli. 3-octaprenyl-4-hydroxybenzoate carboxy-lyase
作者:R.A. Leppik、I.G. Young、F. Gibson
DOI:10.1016/0005-2736(76)90407-7
日期:1976.7
factor of molecular weight less than 10 000. The carboxy-lyasereaction was also shown to be strongly stimulated by dithiothreitol and methanol. The properties of the carboxy-lyase are compared with the three other enzymes concerned with ubiquinone biosynthesis in E. coli which have been studied in vitro. The fact that the substrate of the carboxy-lyase is membrane-bound and the enzyme is stimulated
Distribution of isoprenoid quinone structural types in bacteria and their taxonomic implication
作者:M D Collins、D Jones
DOI:10.1128/mr.45.2.316-354.1981
日期:1981.6
Ubiquinone biosynthesis in microorganisms
作者:R Meganathan
DOI:10.1111/j.1574-6968.2001.tb10831.x
日期:2001.9
The quinoid nucleus of the benzoquinone, ubiquinone (coenzyme Q; Q), is derived from the shikimate pathway in bacteria and eukaryotic microorganisms. Ubiquinone is not considered a vitamin since mammals synthesize it from the essential amino acid tyrosine. Escherichia coli and other Gram-negative bacteria derive the 4-hydroxybenzoate required for the biosynthesis of Q directly from chorismate. The yeast, Saccharomyces cerevisiae, can either form 4-hydroxybenzoate from chorismate or tyrosine. However, unlike mammals, S. cerevisiae synthesizes tyrosine in vivo by the shikimate pathway. While the reactions of the pathway leading from 4-hydroxybenzoate to Q are the same in both organisms the order in which they occur differs. The 4-hydroxybenzoate undergoes a prenylation, a decarboxylation and three hydroxylations alternating with three methylation reactions, resulting in the formation of Q. The methyl groups for the methylation reactions are derived from S-adenosylmethionine. While the prenyl side chain is formed by the 2-C-methyl-d-erythritol 4-phosphate (non-mevalonate) pathway in E. coli, it is formed by the mevalonate pathway in the yeast.
Biosynthesis of Menaquinone (Vitamin K
<sub>2</sub>
) and Ubiquinone (Coenzyme Q)
作者:R. Meganathan、Ohsuk Kwon
DOI:10.1128/ecosalplus.3.6.3.3
日期:2009.2.13
biosyntheses. The prenyl sidechain in MK biosynthesis is introduced at the penultimate step, accompanied by decarboxylation, whereas in Q biosynthesis it is introduced at the second step, with retention of the carboxyl group. In MK biosynthesis, all the reactions of the pathway up to prenylation are carried out by soluble enzymes, whereas all the enzymes involved in Q biosynthesis except the first are