Radical S-adenosylmethionine (SAM) enzymes are a superfamily of enzymes that use SAM and reduced [4Fe-4S] cluster to generate a 5′-deoxyadenosyl radical to catalyze numerous challenging reactions. We have been working a type of non-canonical radical SAM enzymes in the diphthamide biosynthesis pathway. Diphthamide is a post-translationally modified histidine residue found on archaeal and eukaryotic translation elongation factor 2 (EF2). These enzymes also use SAM and reduced [4Fe-4S] clusters, but generate a 3-amino-3-carboxypropyl (ACP) radical to modify the substrate protein, EF2. The presentation will highlight some recent understandings of how diphthamide biosynthetic radical SAM enzyme achieves the unique regioselective cleavage of SAM and what the reaction mechanism is. These understandings will help us to understand all radical SAM enzymes. <br/>

Chemistry of diphthamide biosynthetic radical SAM enzymes

2019 Spring National Meeting

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