N(6)-dimethylallyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + S-adenosyl-L-methionine = 2-thio-N(6)-dimethylallyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + H(+) — reaction