Journal
JOURNAL OF INORGANIC BIOCHEMISTRY
Volume 104, Issue 6, Pages 683-690Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.jinorgbio.2010.02.011
Keywords
Manganese; Peroxidase; Crystallography; Atomic resolution; Refinement
Funding
- National Institutes of Health [GM42614]
- National Science Foundation [MCB-9808420]
- Division of Energy Biosciences, U.S. Department of Energy [DE-03-96ER20235]
- Department of Energy, Office of Biological and Environmental Research
- National Center for Research Resources
- National Institute of General Medical Sciences
- Biomedical Technology Program
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM042614] Funding Source: NIH RePORTER
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Manganese peroxidase (MnP) is an extracellular heme enzyme produced by the lignin-degrading white-rot fungus Phanerochaete chrysosporium. MnP catalyzes the peroxide-dependent oxidation of Mn(II) to Mn(III). The Mn(III) is released from the enzyme in complex with oxalate, enabling the oxalate-Mn(III) complex to serve as a diffusible redox mediator capable of oxidizing lignin, especially under the mediation of unsaturated fatty acids. One heme propionate and the side chains of Glu35, Glu39 and Asp179 have been identified as Mn(II) ligands in our previous crystal structures of native MnP. In our current work, new 0.93 angstrom and 1.05 angstrom crystal structures of MnP with and without bound Mn(II), respectively, have been solved. This represents only the sixth structure of a protein of this size at 0.93 angstrom resolution. In addition, this is the first structure of a heme peroxidase from a eukaryotic organism at sub-Angstrom resolution. These new structures reveal an ordering/disordering of the C-terminal loop, which is likely required for Mn binding and release. In addition, the catalytic Arg42 residue at the active site, normally thought to function only in the peroxide activation process, also undergoes ordering/disordering that is coupled to a transient H-bond with the Mn ligand, Glu39. Finally, these high-resolution structures also reveal the exact H atoms in several parts of the structure that are relevant to the catalytic mechanism. (C) 2010 Elsevier Inc. All rights reserved.
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