CTU2 is a family of proteins necessary for the formation of the wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine in Saccharomyces cerevisiae. The family is conserved from plants to humans ]1]. It plays a central role in the 2-thiolation of 5-methoxycarbonylmethyl-2-thiouridine, or the wobble nucleoside [2]. This wobble modification in tRNAs, 5-methoxycarbonylmethyl-2-thiouridine (mcm(5)s(2)U), is required for the proper decoding of NNR codons in eukaryotes. The 2-thio group gives rigidity by largely fixing the C3'-endo ribose puckering, ensuring stable and accurate codon-anticodon pairing [3].

1: The conserved Wobble uridine tRNA thiolase Ctu1-Ctu2 is required to maintain genome integrity. Dewez M, Bauer F, Dieu M, Raes M, Vandenhaute J, Hermand D; Proc Natl Acad Sci U S A. 2008;105:5459-5464. PMID:18391219

2: A genome-wide screen identifies genes required for formation of the wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine in Saccharomyces cerevisiae. Huang B, Lu J, Bystrom AS; RNA. 2008;14:2183-2194. PMID:18755837

3: Mechanistic characterization of the sulfur-relay system for eukaryotic 2-thiouridine biogenesis at tRNA wobble positions. Noma A, Sakaguchi Y, Suzuki T; Nucleic Acids Res. 2009;37:1335-1352. PMID:19151091