Catalyzes the synthesis of dihydrouridine, a modified base, in various RNAs, such as tRNAs, mRNAs and some long non-coding RNAs (lncRNAs). Mainly modifies the uridine in position 47 (U47) in the D-loop of most cytoplasmic tRNAs. Also able to mediate the formation of dihydrouridine in some mRNAs, thereby regulating their translation. 5,6-dihydrouridine(47) in tRNA + NAD(+) = H(+) + NADH + uridine(47) in tRNA 5,6-dihydrouridine(47) in tRNA + NADP(+) = H(+) + NADPH + uridine(47) 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 Belongs to the Dus family. Dus3 subfamily.