Methylthiotransferase
InterPro Family
Methylthiotransferases are enzymes of the radical S-adenosyl methionine (radical SAM) superfamily. These enzymes catalyze the addition of a methylthio group to various biochemical compounds including tRNA and proteins. Methylthiotransferases are classified into one of four classes based on their substrates and mechanisms. All methylthiotransferases have been shown to contain two Fe-S clusters, one canonical cluster and one auxiliary cluster, that both function in the addition of the methylthio group to the substrate.
Overview
Methylthiotransferases, also known as MTTases, are a subset of the radical SAM enzyme superfamily. These enzymes catalyze the addition of a methylthio group to either a protein or tRNA substrate. Radical S-adenosylmethionine enzymes, otherwise known as radical SAM enzymes, are metalloproteins that cleave S-adenosyl-L-methionine into L-methionine and a 5'-deoxyadenosyl 5'-radical (5'-dA). 5'-dA is an intermediate in the reactions catalyzed by radical SAMs. 5'-dA removes a hydrogen from the substrate and allows for the addition of another group to that carbon on the substrate. In order to complete their reactions, all radical SAMs require a reduced [4Fe-4S] cluster, which is found through a conserved cysteine motif, CX3CX2C. Radical SAMs can have one or multiple Fe-S clusters.
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This entry incorporates text from “Methylthiotransferase” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.