| Primary Identifier | IPR035107 | Type | Family |
| Short Name | tRNA_thiolation_TtcA_Ctu1 |
| description | This entry represents a group of tRNA thiolation proteins. It includes the tRNA-cytidine(32) 2-sulfurtransferase (), and Cytoplasmic tRNA 2-thiolation protein 1 ().tRNA-cytidine(32) 2-sulfurtransferase (also known as 2-thiocytidine tRNA biosynthesis protein TtcA) is required for the thiolation of cytidine in position 32 of tRNA, to form 2-thiocytidine (s(2)C32). The modified nucleoside 2-thiocytidine (s(2)C) has so far been found in tRNA from archaea and bacteria. The TtcA protein family is characterised by the existence of both a PP-loop and a Cys-X(1)-X(2)-Cys motif in the central region of the protein but can be divided into two distinct groups based on the presence and location of additional Cys-X(1)-X(2)-Cys motifs in terminal regions of the sequence. Mutant analysis showed that both cysteines in this central conserved Cys-X(1)-X(2)-Cys motif are required for the formation of s(2)C [].Cytoplasmic tRNA 2-thiolation protein 1 (also known as Ncs6/Tuc1 in budding yeasts) is responsible for 2-thiolation of mcm5S2U at tRNA wobble positions of tRNA(Lys), tRNA(Glu) and tRNA(Gln) [, ]. It directly binds tRNAs and probably acts by catalysing adenylation of tRNAs, an intermediate required for 2-thiolation. Its fission yeast homologue, Ctu1 forms a complex with Ctu2 (Ncs2/Tuc2 homologue) and serves as a putative enzyme for the formation of 2-thiouridine []. This family also includes tRNA-5-methyluridine(54) 2-sulfurtransferase, which catalyses the 2-thiolation of 5-methyluridine residue at position 54 in the T loop of tRNAs, leading to 5-methyl-2-thiouridine []. |
