Is probably a protein kinase regulator of UbiI activity which is involved in aerobic coenzyme Q (ubiquinone) biosynthesis. Required for the expression of 2'-N-acetyltransferase. Cofactor biosynthesis; ubiquinone biosynthesis [regulation]. Cells lacking this gene fail to produce coenzyme Q8, and accumulate octaprenylphenol (OPP). Belongs to the ABC1 family. UbiB subfamily.