title: DpgC is a metal- and cofactor-free 3,5-dihydroxyphenylacetyl-CoA 1,2-dioxygenase in the vancomycin biosynthetic pathway.
abstract: 3,5-Dihydroxyphenylglycine is a crucial amino acid monomer in the nonribosomal glycopeptide antibiotic vancomycin. This nonproteinogenic amino acid is constructed from malonyl-CoA by a set of four enzymes, DpgA-D, in the biosynthetic cluster. DpgC is an unusual metal-free, cofactor-free enzyme that consumes O(2) during the conversion of 3,5-dihydroxyphenylacetyl-CoA (DPA-CoA) to the penultimate intermediate 3,5-dihydroxyphenylglyoxylate (DPGx). We show that in anaerobic incubations, DpgC catalyzes the exchange of the C(2)-methylene hydrogens of DPA-CoA at unequal rates, consistent with enzyme-mediated formation of the substrate-derived C(2)-carbanion as an early intermediate. Incubations with (18)O(2) reveal that DpgC transfers both atoms of an O(2) molecule to DPGx product. This establishes DpgC as a 1,2-dioxygenase that mediates thioester cleavage by the oxygen transfer process. These results are consistent with a DPA-CoA C(2)-peroxy intermediate, followed by enzyme-directed alpha-peroxylactone formation and collapse by O-O bond cleavage.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Claire C
authors.initials: CC
authors.lastname: Tseng
authors.forename: Frédéric H
authors.initials: FH
authors.lastname: Vaillancourt
authors.forename: Steven D
authors.initials: SD
authors.lastname: Bruner
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Walsh
mesh_terms: D000693:Anaerobiosis; D003903:Deuterium / Q000378:metabolism; D049308:Dioxygenases / Q000737:chemistry / Q000378:metabolism*; D008956:Models, Chemical; D015394:Molecular Structure; D010100:Oxygen / Q000378:metabolism; D010103:Oxygen Isotopes / Q000378:metabolism; D011048:Polarography; D021241:Spectrometry, Mass, Electrospray Ionization; D014640:Vancomycin / Q000096:biosynthesis*
chemical_list: D010103:Oxygen Isotopes; D014640:Vancomycin; D003903:Deuterium; D049308:Dioxygenases; D010100:Oxygen