5ff3
HydE from T. maritima in complex with 4R-TCA
Structural highlights
FunctionHYDE_THEMA Required for the maturation of the [FeFe]-hydrogenase HydA (By similarity). Catalyzes the reductive cleavage of S-adenosyl-L-methionine (in vitro), suggesting it may contribute to the biosynthesis of an essential sulfur-containing ligand that binds to the hydrogenase active site [2Fe-2S] cluster (PubMed:16137685).[UniProtKB:Q97IK9][1] Publication Abstract from PubMedCarbon-sulfur bond formation at aliphatic positions is a challenging reaction that is performed efficiently by radical S-adenosyl-L-methionine (SAM) enzymes. Here we report that 1,3-thiazolidines can act as ligands and substrates for the radical SAM enzyme HydE, which is involved in the assembly of the active site of [FeFe]-hydrogenase. Using X-ray crystallography, in vitro assays and NMR spectroscopy we identified a radical-based reaction mechanism that is best described as the formation of a C-centred radical that concomitantly attacks the sulfur atom of a thioether. To the best of our knowledge, this is the first example of a radical SAM enzyme that reacts directly on a sulfur atom instead of abstracting a hydrogen atom. Using theoretical calculations based on our high-resolution structures we followed the evolution of the electronic structure from SAM through to the formation of S-adenosyl-L-cysteine. Our results suggest that, at least in this case, the widely proposed and highly reactive 5'-deoxyadenosyl radical species that triggers the reaction in radical SAM enzymes is not an isolable intermediate. Carbon-sulfur bond-forming reaction catalysed by the radical SAM enzyme HydE.,Rohac R, Amara P, Benjdia A, Martin L, Ruffie P, Favier A, Berteau O, Mouesca JM, Fontecilla-Camps JC, Nicolet Y Nat Chem. 2016 May;8(5):491-500. doi: 10.1038/nchem.2490. Epub 2016 Apr 4. PMID:27102684[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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