Catalyzes the synthesis of dihydrouridine, a modified base found in the D-loop of most tRNAs (PubMed:12003496, PubMed:14970222). Specifically modifies U20 in cytoplasmic tRNAs (PubMed:12003496, PubMed:14970222). Also able to mediate dihydrouridylation of some mRNAs, thereby affecting their translation (By similarity). 5,6-dihydrouridine(20) in tRNA + NADP(+) = H(+) + NADPH + uridine(20) in tRNA 5,6-dihydrouridine(20) in tRNA + NAD(+) = H(+) + NADH + uridine(20) in tRNA a 5,6-dihydrouridine in mRNA + NAD(+) = a uridine in mRNA + H(+) + NADH a 5,6-dihydrouridine in mRNA + NADP(+) = a uridine in mRNA + H(+) + NADPH Monomer. N-glycosylated. Present with 2650 molecules/cell in log phase SD medium. Belongs to the Dus family. Dus2 subfamily.