Catalyzes the conversion of epoxyqueuosine (oQ) to queuosine (Q), which is a hypermodified base found in the wobble positions of tRNA(Asp), tRNA(Asn), tRNA(His) and tRNA(Tyr). AH2 + epoxyqueuosine(34) in tRNA = A + H2O + queuosine(34) in tRNA Binds 2 [4Fe-4S] clusters per monomer. tRNA modification; tRNA-queuosine biosynthesis. Monomer. Belongs to the QueG family. Truncated N-terminus.