The reduction of epoxyqueuosine (oQ) is the last step in the synthesis of the tRNA modification queuosine (Q). members of this family were predicted to encode for an alternative epoxyqueuosine reductase. Furthermore, it has been suggested that family members are a non-orthologous replacement of queG, responsible for oQ to Q conversion. QueH contains conserved cysteines that could be involved in the coordination of a Fe/S center in a similar fashion to what has been identified in QueG. No cobalamin was identified associated with recombinant QueH protein, indicating that the reduction activity is independent from cobalamin [1].

1: Identification of a Novel Epoxyqueuosine Reductase Family by Comparative Genomics. Zallot R, Ross R, Chen WH, Bruner SD, Limbach PA, de Crecy-Lagard V; ACS Chem Biol. 2017;12:844-851. PMID:28128549