title: Biochemical and genetic studies on ubiquinone biosynthesis in Escherichia coli K-12:4-hydroxybenzoate octaprenyltransferase.
abstract: Three ubiquinone-deficient mutants of Escherichia coli unable to convert 4-hydroxybenzoate into 3-octaprenyl-4-hydroxybenzoate were isolated and examined. The results of genetic analysis suggest that each of the mutants carries a mutation in a gene designated ubiA which can be represented at minute 79 on the E. coli chromosome map. The conversion of 4-hydroxybenzoate into 3-octaprenyl-4-hydroxybenzoate, catalyzed by 4-hydroxybenzoate octaprenyltransferase, was studied with a strain of E. coli that is blocked in the common pathway of aromatic biosynthesis and consequently accumulates the precursor of the side chain of ubiquinone. Both the side-chain precursor and 4-hydroxybenzoate octaprenyltransferase were shown to be membrane-bound. The enzyme required Mg(2+) for optimal activity. The ubiA(-) mutants were found to lack 4-hydroxybenozate octaprenyltransferase activity, which suggested that the ubiA gene is the structural gene coding for this enzyme.
mesh_terms: D019883:Alkyl and Aryl Transferases; D001565:Benzoates / Q000494:pharmacology; D002247:Carbon Isotopes; D002855:Chromatography, Thin Layer; D002874:Chromosome Mapping; D003090:Coliphages; D004789:Enzyme Activation; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D005796:Genes; D005827:Genetics, Microbial; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009154:Mutation; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D013729:Terpenes; D014161:Transduction, Genetic; D014166:Transferases; D014451:Ubiquinone / Q000096:biosynthesis*
chemical_list: D001565:Benzoates; D002247:Carbon Isotopes; D013729:Terpenes; D014451:Ubiquinone; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C021386:4-hydroxybenzoate polyprenyltransferase; D008274:Magnesium