Catalyzes the elongation of the C(40) carotenoid all-trans-lycopene to the acyclic C(50) carotenoid flavuxanthin during decaprenoxanthin biosynthesis (PubMed:11432736). Acts as a bifunctional enzyme that catalyzes the elongation of lycopene by attaching a C(5) isoprene unit at C-2, as well as the hydroxylation of the new isoprene unit (Probable). The enzyme acts at both ends of the substrate, forming the C(50) carotenoid flavuxanthin via the C(45) intermediate nonaflavuxanthin (PubMed:11432736). A + all-trans-lycopene + dimethylallyl diphosphate + H2O = AH2 + diphosphate + nonaflavuxanthin A + dimethylallyl diphosphate + H2O + nonaflavuxanthin = AH2 + diphosphate + flavuxanthin Carotenoid biosynthesis. Disruption mutant accumulates lycopene and shows altered carotenoid biosynthesis. Belongs to the UbiA prenyltransferase family.