title: A pyridoxal phosphate-dependent enzyme that oxidizes an unactivated carbon-carbon bond.
abstract: Pyridoxal 5'-phosphate (PLP)-dependent enzymes have wide catalytic versatility but are rarely known for their ability to react with oxygen to catalyze challenging reactions. Here, using in vitro reconstitution and kinetic analysis, we report that the indolmycin biosynthetic enzyme Ind4, from Streptomyces griseus ATCC 12648, is an unprecedented O2- and PLP-dependent enzyme that carries out a four-electron oxidation of L-arginine, including oxidation of an unactivated carbon-carbon (C-C) bond. We show that the conjugated product of this reaction, which is susceptible to nonenzymatic deamination, is efficiently intercepted and stereospecifically reduced by the partner enzyme Ind5 to give D-4,5-dehydroarginine. Thus, Ind4 couples the redox potential of O2 with the ability of PLP to stabilize anions to efficiently oxidize an unactivated C-C bond, with the subsequent stereochemical inversion by Ind5 preventing off-pathway reactions. Altogether, these results expand our knowledge of the catalytic versatility of PLP-dependent enzymes and enrich the toolbox for oxidative biocatalysis.
authors.affiliation: Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Du
authors.affiliation: Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Rahul
authors.initials: R
authors.lastname: Singh
authors.affiliation: Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Lona M
authors.initials: LM
authors.lastname: Alkhalaf
authors.affiliation: Genome Science and Technology Program, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Eugene
authors.initials: E
authors.lastname: Kuatsjah
authors.affiliation: Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: He
authors.affiliation: Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Lindsay D
authors.initials: LD
authors.lastname: Eltis
authors.affiliation: Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Ryan
mesh_terms: D001120:Arginine / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D003641:Deamination; D007700:Kinetics; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000737:chemistry*; D013237:Stereoisomerism; D013305:Streptomyces griseus / Q000201:enzymology
chemical_list: D011732:Pyridoxal Phosphate; D002244:Carbon; D001120:Arginine; D044925:Oxidoreductases Acting on CH-CH Group Donors