Required for O(2)-independent ubiquinone (coenzyme Q) biosynthesis. Together with UbiU, is essential for the C6-hydroxylation reaction in the oxygen-independent ubiquinone biosynthesis pathway. Cofactor biosynthesis; ubiquinone biosynthesis. Forms an heterodimer with UbiU. Deletion mutant is unable to synthesize ubiquinone under strict anaerobic conditions. Mutant shows normal levels of ubiquinone after aerobic growth. Belongs to the peptidase U32 family. UbiV subfamily.