ubiI, a New Gene in Escherichia coli Coenzyme Q Biosynthesis, Is Involved in Aerobic C5-hydroxylation.Chehade, M.H., Loiseau, L., Lombard, M., Pecqueur, L., Ismail, A., Smadja, M., Golinelli-Pimpaneau, B., Mellot-Draznieks, C., Hamelin, O., Aussel, L., Kieffer-Jaquinod, S., Labessan, N., Barras, F., Fontecave, M., Pierrel, F.
(2013) J.Biol.Chem. 288: 20085-20092
- PubMed: 23709220
- DOI: 10.1074/jbc.M113.480368
- PubMed 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. Q biosynthesis is a complex pathway that involves multiple proteins. In this wor ...
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.
Commissariat à l'Energie Atomique, Institut de Recherches en Technologies et Sciences pour le Vivant, Laboratoire Chimie et Biologie des Métaux, F-38054 Grenoble, France.