RT Journal Article SR Electronic(1) A1 Wu, Guanghui A1 Williams, Huw D. A1 Zamanian, Maryam A1 Gibson, Frank A1 Poole, Robert K.YR 1992 T1 Isolation and characterization of Escherichia coli mutants affected in aerobic respiration: the cloning and nucleotide sequence of ubiG JF Microbiology, VO 138 IS 10 SP 2101 OP 2112 DO https://doi.org/10.1099/00221287-138-10-2101 PB Microbiology Society, SN 1465-2080, AB We report the isolation and characterization of a mutant of Escherichia coli unable to grow aerobically on non-fermentable substrates, except for very slow growth on glycerol. The mutant contains cytochrome oxidases o and d, and grows anaerobically with alternative electron acceptors. Oxygen consumption rates of cell-free extracts were low relative to activities in an isogenic control strain, but were restored in vitro by adding ubiquinone-1 to cell-free extracts. Transformation with a cloned 2.8 kb ClaI-EcoRV fragment of chromosomal DNA restored the ability of this mutant (AN2571) to grow on succinate and also restored cellular quinone levels in this strain. The plasmid also complemented a previously isolated ubiG mutant (AN151) for aerobic growth on succinate. The nucleotide sequence revealed a 0.7 kb portion of gyrA. Unidirectional nested deletions from this fragment and complementation analysis identified an open reading frame encoding a protein with a predicted molecular mass of 26.5 kDa. This gene (ubiG) encodes the enzyme 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase, which catalyses the terminal step in the biosynthesis of ubiquinone. The open reading frame is preceded by a putative Shine-Dalgarno sequence and followed by three palindromic unit sequences. Comparison of the inferred amino acid sequence of UbiG with the sequence of other S-adenosylmethionine (AdoMet)-dependent methyltransferases reveals a highly conserved AdoMet-binding region. The cloned 2.8 kb fragment also contains a sequence encoding the C-terminus of a protein with 42–44% identity to fungal acetyl-CoA synthetases., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-138-10-2101