Accepted name: N6-L-threonylcarbamoyladenine synthase
Reaction: L-threonylcarbamoyladenylate + adenine37 in tRNA = AMP + N6-L-threonylcarbamoyladenine37 in tRNA
Glossary: N6-L-threonylcarbamoyladenine37 = t6A37
Other name(s): t6A synthase; Kae1; ygjD (gene name); Qri7
Systematic name: L-threonylcarbamoyladenylate:adenine37 in tRNA N6-L-threonylcarbamoyltransferase
Comments: The enzyme is involved in the synthesis of N6-threonylcarbamoyladenosine37 in tRNAs, which is found in tRNAs with the anticodon NNU, i.e. tRNAIle, tRNAThr, tRNAAsn, tRNALys, tRNASer and tRNAArg [3].
1.  Lauhon, C.T. Mechanism of N6-threonylcarbamoyladenonsine (t6A) biosynthesis: isolation and characterization of the intermediate threonylcarbamoyl-AMP. Biochemistry 51 (2012) 8950–8963. [PMID: 23072323]
2.  Deutsch, C., El Yacoubi, B., de Crecy-Lagard, V. and Iwata-Reuyl, D. Biosynthesis of threonylcarbamoyl adenosine (t6A), a universal tRNA nucleoside. J. Biol. Chem. 287 (2012) 13666–13673. [PMID: 22378793]
3.  Perrochia, L., Crozat, E., Hecker, A., Zhang, W., Bareille, J., Collinet, B., van Tilbeurgh, H., Forterre, P. and Basta, T. In vitro biosynthesis of a universal t6A tRNA modification in Archaea and Eukarya. Nucleic Acids Res. 41 (2013) 1953–1964. [PMID: 23258706]
4.  Wan, L.C.K., Mao, D.Y.L., Neculai, D., Strecker, J., Chiovitti, D., Kurinov, I., Poda, G., Thevakumaran, N., Yuan, F., Szilard, R.K., Lissina, E., Nislow, C., Caudy, A.A., Durocher, D. and Sicheri, F. Reconstitution and characterization of eukaryotic N6-threonylcarbamoylation of tRNA using a minimal enzyme system. Nucleic Acids Res. 41 (2013) 6332–6346. [PMID: 23620299]
[EC created 2014 as EC, transferred 2014 to EC]
Transferred entry: N6-L-threonylcarbamoyladenine synthase. Now EC, N6-L-threonylcarbamoyladenine synthase.
[EC created 2014, deleted 2014]
Accepted name: tRNA (N6-L-threonylcarbamoyladenosine37-C2)-methylthiotransferase
Reaction: N6-L-threonylcarbamoyladenine37 in tRNA + sulfur-(sulfur carrier) + 2 S-adenosyl-L-methionine + reduced electron acceptor = 2-(methylsulfanyl)-N6-L-threonylcarbamoyladenine37 in tRNA + S-adenosyl-L-homocysteine + (sulfur carrier) + L-methionine + 5′-deoxyadenosine + electron acceptor (overall reaction)
(1a) N6-L-threonylcarbamoyladenine37 in tRNA + sulfur-(sulfur carrier) + S-adenosyl-L-methionine + reduced electron acceptor = 2-sulfanyl-N6-L-threonylcarbamoyladenine37 in tRNA + (sulfur carrier) + L-methionine + 5′-deoxyadenosine + electron acceptor
(1b) S-adenosyl-L-methionine + 2-sulfanyl-N6-L-threonylcarbamoyladenine37 in tRNA = S-adenosyl-L-homocysteine + 2-(methylsulfanyl)-N6-L-threonylcarbamoyladenine37 in tRNA
Glossary: N6-L-threonylcarbamoyladenine37 = t6A37
2-sulfanyl-N6-L-threonylcarbamoyladenine37 = ms2t6A37
Other name(s): MtaB; methylthio-threonylcarbamoyl-adenosine transferase B; CDKAL1 (gene name); tRNA (N6-L-threonylcarbamoyladenosine37):sulfur-(sulfur carrier),S-adenosyl-L-methionine C2-methylthiotransferase
Systematic name: tRNA (N6-L-threonylcarbamoyladenosine37):sulfur-(sulfur carrier),S-adenosyl-L-methionine C2-(methylsulfanyl)transferase
Comments: The enzyme, which is a member of the S-adenosyl-L-methionine-dependent radical (radical AdoMet) enzymes superfamily, binds two [4Fe-4S] clusters as well as the transferred sulfur. The sulfur donor is believed to be one of the [4Fe-4S] clusters, which is sacrificed in the process, so that in vitro the reaction is a single turnover. The identity of the electron donor is not known.
1.  Arragain, S., Handelman, S.K., Forouhar, F., Wei, F.Y., Tomizawa, K., Hunt, J.F., Douki, T., Fontecave, M., Mulliez, E. and Atta, M. Identification of eukaryotic and prokaryotic methylthiotransferase for biosynthesis of 2-methylthio-N6-threonylcarbamoyladenosine in tRNA. J. Biol. Chem. 285 (2010) 28425–28433. [PMID: 20584901]
[EC created 2014, modified 2015]