Gated Proton Release during Radical Transfer at the Subunit Interface of Ribonucleotide Reductase
Name
nihms-1663977.pdf
Description
Accepted version
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1.99 MB
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Checksum (MD5)
70e4ee834417864d3cfd9ae1abbfbb7e
Author(s)
Cui, Chang
Greene, Brandon L
Kang, Gyunghoon
Drennan, Catherine L
Stubbe, JoAnne
Nocera, Daniel G
Date Issued
2021
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Citation
Cui, Chang, Greene, Brandon L, Kang, Gyunghoon, Drennan, Catherine L, Stubbe, JoAnne et al. 2021. "Gated Proton Release during Radical Transfer at the Subunit Interface of Ribonucleotide Reductase." Journal of the American Chemical Society, 143 (1).
Version
Author's final manuscript
Abstract
© The class Ia ribonucleotide reductase of Escherichia coli requires strict regulation of long-range radical transfer between two subunits, α and β, through a series of redox-active amino acids (Y122•[β] ↔ W48?[β] ↔ Y356[β] ↔ Y731[α] ↔ Y730[α] ↔ C439[α]). Nowhere is this more precarious than at the subunit interface. Here, we show that the oxidation of Y356 is regulated by proton release involving a specific residue, E52[β], which is part of a water channel at the subunit interface for rapid proton transfer to the bulk solvent. An E52Q variant is incapable of Y356 oxidation via the native radical transfer pathway or non-native photochemical oxidation, following photosensitization by covalent attachment of a photo-oxidant at position 355[β]. Substitution of Y356 for various FnY analogues in an E52Q-photoβ2, where the side chain remains deprotonated, recovered photochemical enzymatic turnover. Transient absorption and emission data support the conclusion that Y356 oxidation requires E52 for proton management, suggesting its essential role in gating radical transport across the protein-protein interface.
MIT Department
Massachusetts Institute of Technology. Department of Biology
Massachusetts Institute of Technology. Department of Chemistry
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1021/JACS.0C07879
