1. ubil, a New Gene in Escherichia coli Coenzyme Q Biosynthesis, Is Involved in Aerobic C5-hydroxylation.
- Author
-
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, and Pierrel, Fabien
- Subjects
- *
BACTERIAL genetics , *ESCHERICHIA coli , *UBIQUINONES , *BIOSYNTHESIS , *HYDROXYLATION , *MONOOXYGENASES , *HYDROXYBENZOATES - Abstract
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.Qbiosynthesis 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 ofQand accumulates a compound derived from theQbiosynthetic 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.Wehave 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 aerobicQbiosynthesis in E. coli are known. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF