<p>This entry represents the FAD-dependent monooxygenase responsible for the second hydroxylation step in the aerobic ubiquinone biosynthetic pathway [<cite idref="PUB00013848"/>]. The sequences in this entry are restricted to the proteobacteria. This family is closely related to the UbiF hydroxylase which catalyses the final hydroxylation step. The enzyme has also been named VisB due to a mutant visible light sensitive phenotype.</p>