Direct Interfacial Y731 Oxidation in α2 by a Photoβ2 Subunit of E. Coli Class Ia Ribonucleotide Reductase

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Direct Interfacial Y731 Oxidation in α2 by a Photoβ2 Subunit of E. Coli Class Ia Ribonucleotide Reductase

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dc.contributor.author Song, David Y.
dc.contributor.author Pizano, Arturo A.
dc.contributor.author Holder, Patrick G.
dc.contributor.author Stubbe, JoAnne
dc.contributor.author Nocera, Daniel
dc.date.accessioned 2017-07-20T14:43:00Z
dc.date.issued 2015
dc.identifier Quick submit: 2017-05-11T12:22:16-0400
dc.identifier.citation Song, David Y., Arturo A. Pizano, Patrick G. Holder, JoAnne Stubbe, and Daniel G. Nocera. 2015. Direct Interfacial Y731 Oxidation in α2 by a Photoβ2 Subunit of E. Coli Class Ia Ribonucleotide Reductase.” Chem. Sci. 6 (8): 4519–4524. doi:10.1039/c5sc01125f. en_US
dc.identifier.issn 2041-6520 en_US
dc.identifier.uri http://nrs.harvard.edu/urn-3:HUL.InstRepos:33468941
dc.description.abstract Proton-coupled electron transfer (PCET) is a fundamental mechanism important in a wide range of biological processes including the universal reaction catalysed by ribonucleotide reductases (RNRs) in making de novo, the building blocks required for DNA replication and repair. These enzymes catalyse the conversion of nucleoside diphosphates (NDPs) to deoxynucleoside diphosphates (dNDPs). In the class Ia RNRs, NDP reduction involves a tyrosyl radical mediated oxidation occurring over 35 Å across the interface of the two required subunits (β2 and α2) involving multiple PCET steps and the conserved tyrosine triad [Y356(β2)–Y731(α2)–Y730(α2)]. We report the synthesis of an active photochemical RNR (photoRNR) complex in which a Re(I)-tricarbonyl phenanthroline ([Re]) photooxidant is attached site-specifically to the Cys in the Y356C-(β2) subunit and an ionizable, 2,3,5-trifluorotyrosine (2,3,5-F3Y) is incorporated in place of Y731 in α2. This intersubunit PCET pathway is investigated by ns laser spectroscopy on [Re356]-β2:2,3,5-F3Y731-α2 in the presence of substrate, CDP, and effector, ATP. This experiment has allowed analysis of the photoinjection of a radical into α2 from β2 in the absence of the interfacial Y356 residue. The system is competent for light-dependent substrate turnover. Time-resolved emission experiments reveal an intimate dependence of the rate of radical injection on the protonation state at position Y731(α2), which in turn highlights the importance of a well-coordinated proton exit channel involving the key residues, Y356 and Y731, at the subunit interface. en_US
dc.description.sponsorship Chemistry and Chemical Biology en_US
dc.language.iso en_US en_US
dc.publisher Royal Society of Chemistry (RSC) en_US
dc.relation.isversionof doi:10.1039/C5SC01125F en_US
dash.license LAA
dc.title Direct Interfacial Y731 Oxidation in α2 by a Photoβ2 Subunit of E. Coli Class Ia Ribonucleotide Reductase en_US
dc.type Journal Article en_US
dc.date.updated 2017-05-11T16:21:43Z
dc.description.version Version of Record en_US
dc.relation.journal Chem. Sci. en_US
dash.depositing.author Nocera, Daniel
dc.date.available 2015
dc.date.available 2017-07-20T14:43:00Z

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