title: Biosynthetic versatility and coordinated action of 5'-deoxyadenosyl radicals in deazaflavin biosynthesis.
abstract: Coenzyme F420 is a redox cofactor found in methanogens and in various actinobacteria. Despite the major biological importance of this cofactor, the biosynthesis of its deazaflavin core (8-hydroxy-5-deazaflavin, F(o)) is still poorly understood. F(o) synthase, the enzyme involved, is an unusual multidomain radical SAM enzyme that uses two separate 5'-deoxyadenosyl radicals to catalyze F(o) formation. In this paper, we report a detailed mechanistic study on this complex enzyme that led us to identify (1) the hydrogen atoms abstracted from the substrate by the two radical SAM domains, (2) the second tyrosine-derived product, (3) the reaction product of the CofH-catalyzed reaction, (4) the demonstration that this product is a substrate for CofG, and (5) a stereochemical study that is consistent with the formation of a p-hydroxybenzyl radical at the CofH active site. These results enable us to propose a mechanism for F(o) synthase and uncover a new catalytic motif in radical SAM enzymology involving the use of two 5'-deoxyadenosyl radicals to mediate the formation of a complex heterocycle.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Philmus
authors.affiliation: ‡ChemSyBio, UMR 1319 Micalis, INRA, F-78350 Jouy-en-Josas, France.|§ChemSyBio, UMR Micalis, AgroParisTech, F-78350 Jouy-en-Josas, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Decamps
authors.affiliation: ‡ChemSyBio, UMR 1319 Micalis, INRA, F-78350 Jouy-en-Josas, France.|§ChemSyBio, UMR Micalis, AgroParisTech, F-78350 Jouy-en-Josas, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Berteau
authors.forename: Tadhg P
authors.initials: TP
authors.lastname: Begley
mesh_terms: D039903:Actinobacteria / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D053898:Biosynthetic Pathways; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism*; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D012258:Riboflavin Synthase / Q000378:metabolism*; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
chemical_list: D005609:Free Radicals; D014443:Tyrosine; C015084:coenzyme F420; D012258:Riboflavin Synthase; D012256:Riboflavin