Dihydrouridine synthase. Catalyzes the NADPH-dependent synthesis of dihydrouridine, a modified base found in the D-loop of most tRNAs. Negatively regulates the activation of EIF2AK2/PKR. 5,6-dihydrouridine(20) in tRNA + NADP(+) = H(+) + NADPH + uridine(20) in tRNA Interacts with EPRS1. Interacts (via DRBM domain) with PRKRA and EIF2AK2/PKR (via DRBM 1 domain). Mainly at the endoplasmic reticulum. Efficient dihydrouridine synthesis requires the presence of both the catalytic domain and the C-terminal RNA-binding DRBM domain. Belongs to the Dus family. Dus2 subfamily.