ubiI, a New Gene in Escherichia coli Coenzyme Q Biosynthesis, Is Involved in Aerobic C5-hydroxylation

作者：Chehade Mahmoud Hajj; Loiseau Laurent; Lombard Murielle; Pecqueur Ludovic; Ismail Alexandre; Smadja Myriam; Golinelli Pimpaneau Beatrice; Mellot Draznieks Caroline; Hamelin Olivier; Aussel Laurent; Kieffer Jaquinod Sylvie; Labessan Natty; Barras Frederic; Fontecave Marc; Pierrel Fabien^*

来源：Journal of Biological Chemistry, 2013, 288(27): 20085-20092.

DOI：10.1074/jbc.M113.480368

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.

• 出版日期2013-7-5
• 单位中国地震局