Carbon-sulfur bond-forming reaction catalysed by the radical SAM enzyme HydE.
Carbon-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.
Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, UGA, 71 Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
Roman
R
Rohac
Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, UGA, 71 Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
Patricia
P
Amara
Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.
Alhosna
A
Benjdia
Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, UGA, 71 Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
Lydie
L
Martin
Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.
Pauline
P
Ruffié
Biomolecular NMR Spectroscopy Group, Institut de Biologie Structurale, CEA, CNRS, UGA, 71 Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
Adrien
A
Favier
Micalis Institute, ChemSyBio, INRA, AgroParisTech, Université Paris-Saclay, F-78350 Jouy-en-Josas, France.
Olivier
O
Berteau
Université Grenoble Alpes, INAC, SCIB/LRM, F-38000 Grenoble, France.|CEA, INAC, SCIB/LRM, F-38054 Grenoble, France.
Jean-Marie
JM
Mouesca
Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, UGA, 71 Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
Juan C
JC
Fontecilla-Camps
Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, UGA, 71 Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
Yvain
Y
Nicolet
D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D020134:Catalytic Domain; D046969:Clostridium acetobutylicum / Q000201:enzymology; D003545:Cysteine / Q000031:analogs & derivatives / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D008024:Ligands; D008956:Models, Chemical; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry*; D011789:Quantum Theory; D012436:S-Adenosylmethionine / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry; D020124:Thermotoga maritima / Q000201:enzymology; D053778:Thiazolidines / Q000737:chemistry*
D005609:Free Radicals; D008024:Ligands; D053778:Thiazolidines; D013455:Sulfur; D002244:Carbon; D012436:S-Adenosylmethionine; D050862:Oxidoreductases Acting on Sulfur Group Donors; D003545:Cysteine