Modulation of Y [subscript 356] Photooxidation in E. Coli Class Ia Ribonucleotide Reductase by Y [subscript 731] Across the α [subscript 2] :β [subscript 2] Interface
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Author(s)
Pizano, Arturo A.
Olshansky, Lisa
Holder, Patrick
Stubbe, JoAnne
Nocera, Daniel G.
Date Issued
August 2013
Journal
Journal of the American Chemical Society
Publisher
American Chemical Society (ACS)
Citation
Pizano, Arturo A., Lisa Olshansky, Patrick G. Holder, JoAnne Stubbe, and Daniel G. Nocera. “ Modulation of Y [subscript 356] Photooxidation in E. Coli Class Ia Ribonucleotide Reductase by Y [subscript 731] Across the α [subscript 2] :β [subscript 2] Interface .” Journal of the American Chemical Society 135, no. 36 (September 11, 2013): 13250–13253.
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Author's final manuscript
Abstract
Substrate turnover in class Ia ribonucleotide reductase (RNR) requires reversible radical transport across two subunits over 35 Å, which occurs by a multistep proton-coupled electron-transfer mechanism. Using a photooxidant-labeled β[subscript 2] subunit of Escherichia coli class Ia RNR, we demonstrate photoinitiated oxidation of a tyrosine in an α[subscript 2]:β[subscript 2] complex, which results in substrate turnover. Using site-directed mutations of the redox-active tyrosines at the subunit interface, Y[subscript 356]F(β) and Y[subscript 731]F(α), this oxidation is identified to be localized on Y[subscript 356]. The rate of Y[subscript 356] oxidation depends on the presence of Y[subscript 731] across the interface. This observation supports the proposal that unidirectional PCET across the Y[subscript 356](β)–Y[subscript 731](α)–Y[subscript 730](α) triad is crucial to radical transport in RNR.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/ja405498e
