Serial Femtosecond Zero Dose Crystallography Captures a Water-Free Distal Heme Site in a Dye-Decolorising Peroxidase to Reveal a Catalytic Role for an Arginine in Fe IV =O Formation

Obtaining structures of intact redox states of metal centers derived from zero dose X-ray crystallography can advance our mechanistic understanding of metalloenzymes. In dye-decolorising heme peroxidases (DyPs), controversy exists regarding the mechanistic role of the distal heme residues aspartate...

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Published in:Angewandte Chemie International Edition 2020-11, Vol.59 (48), p.21656-21662
Main Authors: Lučić, Marina, Svistunenko, Dimitri A, Wilson, Michael T, Chaplin, Amanda K, Davy, Bradley, Ebrahim, Ali, Axford, Danny, Tosha, Takehiko, Sugimoto, Hiroshi, Owada, Shigeki, Dworkowski, Florian S N, Tews, Ivo, Owen, Robin L, Hough, Michael A, Worrall, Jonathan A R
Format: Article
Language:English
Subjects:
Arginine - chemistry
Arginine - metabolism
Biocatalysis
Coloring Agents - chemistry
Coloring Agents - metabolism
Crystallography, X-Ray
Heme - chemistry
Heme - metabolism
Iron Compounds - chemistry
Iron Compounds - metabolism
Models, Molecular
Oxidation-Reduction
Oxygen - chemistry
Oxygen - metabolism
Peroxidase - chemistry
Peroxidase - metabolism
Streptomyces lividans - enzymology
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Summary:Obtaining structures of intact redox states of metal centers derived from zero dose X-ray crystallography can advance our mechanistic understanding of metalloenzymes. In dye-decolorising heme peroxidases (DyPs), controversy exists regarding the mechanistic role of the distal heme residues aspartate and arginine in the heterolysis of peroxide to form the catalytic intermediate compound I (Fe =O and a porphyrin cation radical). Using serial femtosecond X-ray crystallography (SFX), we have determined the pristine structures of the Fe and Fe =O redox states of a B-type DyP. These structures reveal a water-free distal heme site that, together with the presence of an asparagine, imply the use of the distal arginine as a catalytic base. A combination of mutagenesis and kinetic studies corroborate such a role. Our SFX approach thus provides unique insight into how the distal heme site of DyPs can be tuned to select aspartate or arginine for the rate enhancement of peroxide heterolysis.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202008622