COQ6 : coenzyme Q6, monooxygenase
Description
The COQ6 (coenzyme Q6, monooxygenase) is a protein-coding gene located on chromosome 14.
The COQ6 gene provides instructions for making an enzyme that carries out one step in the production of a molecule called coenzyme Q10. Coenzyme Q10 has several critical functions in cells throughout the body. In cell structures called mitochondria, coenzyme Q10 plays an essential role in a process called oxidative phosphorylation, which converts the energy from food into a form cells can use. Coenzyme Q10 is also involved in producing pyrimidines, which are building blocks of DNA, its chemical cousin RNA, and molecules such as ATP and GTP that serve as energy sources in the cell. In cell membranes, coenzyme Q10 acts as an antioxidant, protecting cells from damage caused by unstable oxygen-containing molecules (free radicals), which are byproducts of energy production.
The COQ6 gene encodes a FAD-dependent monooxygenase that is essential for ubiquinone (coenzyme Q10) biosynthesis. Specifically, COQ6 catalyzes the hydroxylation of 3-hexaprenyl-4-hydroxybenzoic acid (HHB) to 3-hexaprenyl-4,5-dihydroxybenzoic acid (DHHB). This hydroxylation reaction is crucial for the formation of the C5 ring in the ubiquinone molecule. The electrons required for this reaction are indirectly supplied from NADPH via a ferredoxin/ferredoxin reductase system. Interestingly, when expressed in yeast cells lacking COQ9, COQ6 can also perform a deamination reaction at the C4 position of 3-hexaprenyl-4-amino-5-hydroxybenzoic acid (HHAB) to produce DHHB. However, this deamination reaction does not appear to occur in bacteria, plants, or mammals, where only the C5 hydroxylation of HHB has been observed.
COQ6 is also known as CGI-10, CGI10, COQ10D6.
