Biological process

tRNA wobble uridine thiolation, wobble position s2U biosynthesis

The process in which a uridine residue at position 34 in the anticodon of a tRNA is post-transcriptionally thiolated at the C2 position. This process involves transfer of a sulfur from cysteine to position C2 by several steps.

In E. coli, the first step of the reaction is reductive elimination of sulfur from L-cysteine by IscS cysteine desulfurase to form an enzyme-bound cysteine-persulfide intermediate. Then, five essential gene products, TusA, TusB, TusC, TusD and TusE, mediate a sulfur relay that delivers the terminal sulfur of persulfide from IscS to MnmA12. The last protein, MnmA catalyzes the transfer of the sulfur from IscS to an ATP activated U34 of the tRNA.