Modomics - A Database of RNA Modifications

Full name: Cytoplasmic tRNA 2-thiolation protein 2
Synonym: CTU2, TUC2
GI: 125863506
Orf: N1913
COG: COG0037
UniProt: P53923
Structures: | |
Complex: Nsc2/Ncs6
Enzyme type: thiolase
Position of modification - modification: t:34 - mcm5s2U


Both Ncs2 and Ncs6 are necessary for the thiolation of U54 in cytoplasmic tRNA. The sulphur group originates from cysteine and flows through an intricate enzymatic cascade of reactions to end up as thiocarboxylated Urm1p (Urm1p-COSH) which is the substrate of 2-thiouridine formation catalysed by the complex Ncs2-Ncs6. While starting with the same cysteine desulfurase Nsf1, the rest of the sulphur relay system is different than in mitochondria. It is definitively distinct from the IscS/Tus-proteins dependent system working in bacteria. In nematode and fission yeast, Cut1-Cut2 complex are the homologs of Ncs6-Ncs2 (Tuc1-Tuc2). At variance with bacterial thiolation system, s2U formation at the wobble position 34 in tRNA can occur only after prior C5-modification of uridine ring. Ncs2 and Ncs6 are down-regulated in a proteasomal dependent fashion in yeast exposed to mild heat stress. This down-regulation influences translation of mRNAs rich in codons decoded by tRNAs thiolated by the Ncs2-Ncs6 complex.

Protein sequence:


Enzymatic activities:

Reaction Substrate Type Position
mcm5U:mcm5s2U tRNA (t) Glu/3UC/unknown 34
mcm5U:mcm5s2U tRNA (t) Lys/3UU/unknown 34
mcm5U:mcm5s2U tRNA (t) Gln/3UG/eukaryotic cytosol 34
ncm5U:ncm5s2U tRNA (t) Glu/3UC/unknown 34
ncm5U:ncm5s2U tRNA (t) Lys/3UU/eukaryotic cytosol 34
ncm5U:ncm5s2U tRNA (t) Gln/3UG/eukaryotic cytosol 34
U:s2U tRNA (t) 34


Title Authors Journal Details PubMed Id DOI
Ubiquitin-related modifier Urm1 acts as a sulphur carrier in thiolation of eukaryotic transfer RNA. Leidel S, Pedrioli PG, Bucher T, Brost R, Costanzo M, Schmidt A, Aebersold R, Boone C, Hofmann K, Peter M Nature [details] 19145231 -
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 [details] 19151091 -
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 [details] 18755837 -
Thio-modification of yeast cytosolic tRNA requires a ubiquitin-related system that resembles bacterial sulfur transfer systems. Nakai Y, Nakai M, Hayashi H J Biol Chem [details] 18664566 -
Protein degradation and dynamic tRNA thiolation fine-tune translation at elevated temperatures. Tyagi K, Pedrioli PG... Nucleic Acids Res [details] 25870413 -



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