title: Oxygen Activation at the Active Site of a Fungal Lytic Polysaccharide Monooxygenase.
abstract: Lytic polysaccharide monooxygenases have attracted vast attention owing to their abilities to disrupt glycosidic bonds via oxidation instead of hydrolysis and to enhance enzymatic digestion of recalcitrant substrates including chitin and cellulose. We have determined high-resolution X-ray crystal structures of an enzyme from Neurospora crassa in the resting state and of a copper(II) dioxo intermediate complex formed in the absence of substrate. X-ray crystal structures also revealed "pre-bound" molecular oxygen adjacent to the active site. An examination of protonation states enabled by neutron crystallography and density functional theory calculations identified a role for a conserved histidine in promoting oxygen activation. These results provide a new structural description of oxygen activation by substrate free lytic polysaccharide monooxygenases and provide insights that can be extended to reactivity in the enzyme-substrate complex.
authors.affiliation: Department of Molecular and Structural Biochemistry, North Carolina State University and Biology and Soft Matter Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
authors.forename: William B
authors.identifier: 0000-0002-8063-5190
authors.initials: WB
authors.lastname: O'Dell
authors.affiliation: Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville and Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
authors.forename: Pratul K
authors.initials: PK
authors.lastname: Agarwal
authors.affiliation: Department of Molecular and Structural Biochemistry, North Carolina State University and Biology and Soft Matter Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
authors.forename: Flora
authors.identifier: 0000-0001-9313-8989
authors.initials: F
authors.lastname: Meilleur
mesh_terms: D020134:Catalytic Domain; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009492:Neurospora crassa / Q000201:enzymology*; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D011134:Polysaccharides; D006899:Mixed Function Oxygenases; D010100:Oxygen
keywords: copper; oxidoreductases; oxygen activation; polysaccharide monooxygenases; protein structures