tRNA sulfurtransferase ThiI (IPR003720)

Short name: tRNA_STrfase

Overlapping homologous superfamilies

Family relationships



tRNA sulfurtransferase ThiI catalyses the ATP-dependent transfer of a sulfur to tRNA to produce 4-thiouridine in position 8 of tRNAs, which functions as a near-UV photosensor [PMID: 11443125, PMID: 16855700, PMID: 18604845]. In some bacteria, ThiI is a bifunctional enzyme required for the synthesis of both the 4-thiouridine modification in tRNA and the thiazole moiety in the thiamine biosynthesis pathway [PMID: 9209060].

Three domains of ThiI are essential for the thiolation of tRNA: a THUMP domain that binds tRNA (see IPR004114) [PMID: 16343540], an AANH domain that activates the uridine residue by adenylylation [PMID: 18604845], and a rhodanese domain that transfers sulfur to the activated uridine residue [PMID: 11443125]. Neither the THUMP nor the AANH domain of ThiI are essential for thiamine synthesis, only the rhodanese domain is necessary for synthesis of the thiazole moiety of thiamine [PMID: 21724998].

GO terms

Biological Process

GO:0034227 tRNA thio-modification

Molecular Function

GO:0016783 sulfurtransferase activity

Cellular Component

GO:0005737 cytoplasm

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.