title: Fine-tuning of a radical-based reaction by radical S-adenosyl-L-methionine tryptophan lyase.
abstract: The radical S-adenosyl-L-methionine tryptophan lyase NosL converts L-tryptophan into 3-methylindolic acid, which is a precursor in the synthesis of the thiopeptide antibiotic nosiheptide. Using electron paramagnetic resonance spectroscopy and multiple L-tryptophan isotopologues, we trapped and characterized radical intermediates that indicate a carboxyl fragment migration mechanism for NosL. This is in contrast to a proposed fragmentation-recombination mechanism that implied Cα-Cβ bond cleavage of L-tryptophan. Although NosL resembles related tyrosine lyases, subtle substrate motions in its active site are responsible for a fine-tuned radical chemistry, which selects the Cα-C bond for disruption. This mechanism highlights evolutionary adaptation to structural constraints in proteins as a route to alternative enzyme function.
authors.affiliation: Université Grenoble-Alpes, Institut Nanosciences et Cryogénie (INAC)-Service de Chimie Inorganique et Biologique (SCIB)/Laboratoire de Résonance Magnétique (LRM), F-38000 Grenoble, France. Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), INAC-SCIB/LRM, F-38000 Grenoble, France.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Sicoli
authors.affiliation: Université Grenoble-Alpes, Institut Nanosciences et Cryogénie (INAC)-Service de Chimie Inorganique et Biologique (SCIB)/Laboratoire de Résonance Magnétique (LRM), F-38000 Grenoble, France. Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), INAC-SCIB/LRM, F-38000 Grenoble, France.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Mouesca
authors.affiliation: Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes, 71, Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Zeppieri
authors.affiliation: Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes, 71, Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
authors.forename: Patricia
authors.initials: P
authors.lastname: Amara
authors.affiliation: Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes, 71, Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
authors.forename: Lydie
authors.initials: L
authors.lastname: Martin
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses, UPR CNRS 3228, F-38048 Grenoble, France.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Barra
authors.affiliation: Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes, 71, Avenue des Martyrs, 38044 Grenoble Cedex 9, France.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Fontecilla-Camps
authors.affiliation: Université Grenoble-Alpes, Institut Nanosciences et Cryogénie (INAC)-Service de Chimie Inorganique et Biologique (SCIB)/Laboratoire de Résonance Magnétique (LRM), F-38000 Grenoble, France. Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), INAC-SCIB/LRM, F-38000 Grenoble, France. yvain.nicolet@ibs.fr serge.gambarelli@cea.fr.
authors.forename: Serge
authors.initials: S
authors.lastname: Gambarelli
authors.affiliation: Metalloproteins Unit, Institut de Biologie Structurale, CEA, CNRS, Université Grenoble-Alpes, 71, Avenue des Martyrs, 38044 Grenoble Cedex 9, France. yvain.nicolet@ibs.fr serge.gambarelli@cea.fr.
authors.forename: Yvain
authors.initials: Y
authors.lastname: Nicolet
mesh_terms: D019755:Carbon-Carbon Lyases / Q000737:chemistry*; D020134:Catalytic Domain; D004578:Electron Spin Resonance Spectroscopy; D007211:Indoles / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000737:chemistry*; D013302:Streptomyces / Q000201:enzymology*; D014364:Tryptophan / Q000737:chemistry*; D014368:Tryptophanase / Q000737:chemistry*
chemical_list: D007211:Indoles; D012436:S-Adenosylmethionine; D014364:Tryptophan; D019755:Carbon-Carbon Lyases; C000606497:S-adenosyl-L-methionine tryptophan lyase, Streptomyces actuosus; D014368:Tryptophanase