EC Number   |
Natural Substrates |
|---|
  2.8.1.B3 | more |
ThiI is responsible for the formation of the modified base 4-thiouridine found at position 8 in some prokaryotic tRNAs. This base acts as a sensitive trigger for the response mechanism to UV exposure, providing protection against its damaging effects |
| 2.8.1.B3 | more |
the enzyme is not able to enhance cysteine desulfurase NifZ activity of sulfide or alanine formation |
| 2.8.1.B3 | more |
three domains of ThiI are essential for the thiolation of tRNA: a THUMP domain that binds tRNA, an AANH domain that activates the uridine residue by adenylylation, and a rhodanese domain that transfers sulfur to the activated uridine residue. Only the rhodanese domain of the ThiI protein is required for a key thiolation reaction in the synthesis of thiamine, while the other two domains (THUMP and AANH) are dispensable |
| 2.8.1.B3 | more |
the enzyme also displays an ATP diphosphatase activity for the adenylation of uridine |
| 2.8.1.B3 | sulfurtransferase IscS-SSH + adenylated-tRNA-uridine(position8) |
- |
| 2.8.1.B3 | sulfurtransferase IscS-SSH + adenylated-tRNA-uridine(position8) |
the biosynthesis of 4-thiouridine in Escherichia coli tRNA requires the action of both the thiamine pathway enzyme ThiI and the cysteine desulfurase IscS. IscS catalyzes sulfur transfer from L-cysteine to ThiI, which utilizes MgATP2- to activate uridine 8 in tRNA and transfers sulfur to give s4U |
| 2.8.1.B3 | sulfurtransferase IscS-SSH + adenylated-tRNA-uridine(position8) |
ThiI is a recipient of S(0) from IscS and catalyzes the ultimate sulfur transfer step in the biosynthesis of 4-thiouridine |
