EC Explorer

2.8.4.5

tRNA (N⁶-L-threonylcarbamoyladenosine³⁷-C²)-methylthiotransferase

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

MtaB, methylthio-threonylcarbamoyl-adenosine transferase B, CDKAL1 (gene name), tRNA (N⁶-L-threonylcarbamoyladenosine³⁷):sulfur-(sulfur carrier),S-adenosyl-L-methionine C²-methylthiotransferase

tRNA (N⁶-L-threonylcarbamoyladenosine³⁷):sulfur-(sulfur carrier),S-adenosyl-L-methionine C²-(methylsulfanyl)transferase

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.

created 2014, modified 2015