title: Emerging themes in radical SAM chemistry.
abstract: Enzymes in the radical SAM (RS) superfamily catalyze a wide variety of reactions through unique radical chemistry. The characteristic markers of the superfamily include a [4Fe-4S] cluster coordinated to the protein via a cysteine triad motif, typically CX(3)CX(2)C, with the fourth iron coordinated by S-adenosylmethionine (SAM). The SAM serves as a precursor for a 5'-deoxyadenosyl radical, the central intermediate in nearly all RS enzymes studied to date. The SAM-bound [4Fe-4S] cluster is located within a partial or full triosephosphate isomerase (TIM) barrel where the radical chemistry occurs protected from the surroundings. In addition to the TIM barrel and a RS [4Fe-4S] cluster, many members of the superfamily contain additional domains and/or additional Fe-S clusters. Recently characterized superfamily members are providing new examples of the remarkable range of reactions that can be catalyzed, as well as new structural and mechanistic insights into these fascinating reactions.
authors.affiliation: Department of Chemistry & Biochemistry and the Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, MT 59717, United States.
authors.forename: Krista A
authors.initials: KA
authors.lastname: Shisler
authors.forename: Joan B
authors.initials: JB
authors.lastname: Broderick
mesh_terms: D000818:Animals; D055162:Biocatalysis; D005609:Free Radicals / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D012436:S-Adenosylmethionine / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005609:Free Radicals; D012436:S-Adenosylmethionine