title: The role of UbiX in Escherichia coli coenzyme Q biosynthesis.
abstract: The reversible redox chemistry of coenzyme Q serves a crucial function in respiratory electron transport. Biosynthesis of Q in Escherichia coli depends on the ubi genes. However, very little is known about UbiX, an enzyme thought to be involved in the decarboxylation step in Q biosynthesis in E. coli and Salmonella enterica. Here we characterize an E. coli ubiX gene deletion strain, LL1, to further elucidate E. coli ubiX function in Q biosynthesis. LLI produces very low levels of Q, grows slowly on succinate as the sole carbon source, accumulates 4-hydroxy-3-octaprenyl-benzoate, and has reduced UbiG O-methyltransferase activity. Expression of either E. coli ubiX or the Saccharomyces cerevisiae ortholog PAD1, rescues the deficient phenotypes of LL1, identifying PAD1 as an ortholog of ubiX. Our results suggest that both UbiX and UbiD are required for the decarboxylation of 4-hydroxy-3-octaprenyl-benzoate in E. coli coenzyme Q biosynthesis, especially during logarithmic growth.
authors: Department of Chemistry and Biochemistry and The Molecular Biology Institute, University of California Los Angeles, 607 Charles E. Young Dr., Los Angeles, CA 90095-1569, USA.
authors: Melissa
authors: M
authors: Gulmezian
authors: Kyle R
authors: KR
authors: Hyman
authors: Beth N
authors: BN
authors: Marbois
authors: Catherine F
authors: CF
authors: Clarke
authors: George T
authors: GT
authors: Javor
mesh_terms: D002262:Carboxy-Lyases / Q000378:metabolism*; D049109:Cell Proliferation; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D014451:Ubiquinone / Q000096:biosynthesis*
chemical_list: D029968:Escherichia coli Proteins; D014451:Ubiquinone; C415986:3-octaprenyl-4-hydroxybenzoate carboxy-lyase; D002262:Carboxy-Lyases; C113304:ubiX protein, E coli