A new gene involved in coenzyme Q biosynthesis in Escherichia coli: UbiI functions in aerobic C5-hydroxylation

Coenzyme Q (ubiquinone or Q) is a redox-active lipid found in organisms ranging from bacteria to mammals in which it plays a crucial role in energy-generating processes. Q biosynthesis is a complex pathway that involves multiple proteins. In this work, we show that the uncharacterized conserved visC...

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Bibliographic Details
Published in:The Journal of biological chemistry 2013-07, Vol.288 (27), p.20085-92
Main Authors: Hajj Chehade, Mahmoud, Loiseau, Laurent, Lombard, Murielle, Pecqueur, Ludovic, Ismail, Alexandre, Smadja, Myriam, Golinelli-Pimpaneau, Béatrice, Mellot-Draznieks, Caroline, Hamelin, Olivier, Aussel, Laurent, Kieffer-Jaquinod, Sylvie, Labessan, Natty, Barras, Frédéric, Fontecave, Marc, Pierrel, Fabien
Format: Article
Language:English
Subjects:
Aerobiosis
Binding Sites
Biochemistry, Molecular Biology
Escherichia coli
Escherichia coli Proteins
Flavin-Adenine Dinucleotide
Hydrolases
Hydroxylation
Life Sciences
Mixed Function Oxygenases
Mutagenesis, Site-Directed
Ubiquinone
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Summary:Coenzyme Q (ubiquinone or Q) is a redox-active lipid found in organisms ranging from bacteria to mammals in which it plays a crucial role in energy-generating processes. Q biosynthesis is a complex pathway that involves multiple proteins. In this work, we show that the uncharacterized conserved visC gene is involved in Q biosynthesis in Escherichia coli, and we have renamed it ubiI. Based on genetic and biochemical experiments, we establish that the UbiI protein functions in the C5-hydroxylation reaction. A strain deficient in ubiI has a low level of Q and accumulates a compound derived from the Q biosynthetic pathway, which we purified and characterized. We also demonstrate that UbiI is only implicated in aerobic Q biosynthesis and that an alternative enzyme catalyzes the C5-hydroxylation reaction in the absence of oxygen. We have solved the crystal structure of a truncated form of UbiI. This structure shares many features with the canonical FAD-dependent para-hydroxybenzoate hydroxylase and represents the first structural characterization of a monooxygenase involved in Q biosynthesis. Site-directed mutagenesis confirms that residues of the flavin binding pocket of UbiI are important for activity. With our identification of UbiI, the three monooxygenases necessary for aerobic Q biosynthesis in E. coli are known.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M113.480368