DUS2 (dihydrouridine synthase 2) catalyzes the NADPH-dependent synthesis of dihydrouridine (D), a modified base in the D-loop of most tRNAs 1. Specifically, DUS2 modifies uridine at position 20 (D20) in cytoplasmic tRNAs, with activity dependent on guanosine presence at position 19 2. Unlike bacterial and fungal homologs, human DUS2 contains three functional modules: an N-terminal catalytic domain binding NADPH flavin cofactor, a conserved α-helical tRNA-binding domain, and an extended double-stranded RNA-binding domain (dsRBD) that serves as the primary tRNA recognition module 3. This unusual dsRBD organization represents an evolutionary innovation distinguishing animal Dus2 enzymes 4. Beyond tRNA modification, DUS2 negatively regulates EIF2AK2/PKR activation, contributing to antiviral immunity 5. Clinically, DUS2 overexpression is associated with lung cancer progression and poorer prognosis through enhanced translation and interaction with aminoacyl-tRNA synthetases 1. DUS2 has also been identified as a shared genetic risk factor in familial autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis 6, and functions as a lung-specific metastasis driver in cancer 7. Additionally, DUS2 deficiency causes pleiotropic effects on multiple tRNA modifications, suggesting complex RNA modification interdependencies 8.