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Generation of a stable, aminotyrosyl radical-induced ?2?2 complex of Escherichia coli class Ia ribonucleotide reductase.


ABSTRACT: Ribonucleotide reductase (RNR) catalyzes the conversion of nucleoside diphosphates to deoxynucleoside diphosphates (dNDPs). The Escherichia coli class Ia RNR uses a mechanism of radical propagation by which a cysteine in the active site of the RNR large (?2) subunit is transiently oxidized by a stable tyrosyl radical (Y•) in the RNR small (?2) subunit over a 35-Å pathway of redox-active amino acids: Y122• ? [W48?] ? Y356 in ?2 to Y731 ? Y730 ? C439 in ?2. When 3-aminotyrosine (NH2Y) is incorporated in place of Y730, a long-lived NH2Y730• is generated in ?2 in the presence of wild-type (wt)-?2, substrate, and effector. This radical intermediate is chemically and kinetically competent to generate dNDPs. Herein, evidence is presented that NH2Y730• induces formation of a kinetically stable ?2?2 complex. Under conditions that generate NH2Y730•, binding between Y730NH2Y-?2 and wt-?2 is 25-fold tighter (Kd = 7 nM) than for wt-?2

SUBMITTER: Minnihan EC 

PROVIDER: S-EPMC3593893 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Generation of a stable, aminotyrosyl radical-induced α2β2 complex of Escherichia coli class Ia ribonucleotide reductase.

Minnihan Ellen C EC   Ando Nozomi N   Brignole Edward J EJ   Olshansky Lisa L   Chittuluru Johnathan J   Asturias Francisco J FJ   Drennan Catherine L CL   Nocera Daniel G DG   Stubbe Joanne J  

Proceedings of the National Academy of Sciences of the United States of America 20130219 10


Ribonucleotide reductase (RNR) catalyzes the conversion of nucleoside diphosphates to deoxynucleoside diphosphates (dNDPs). The Escherichia coli class Ia RNR uses a mechanism of radical propagation by which a cysteine in the active site of the RNR large (α2) subunit is transiently oxidized by a stable tyrosyl radical (Y•) in the RNR small (β2) subunit over a 35-Å pathway of redox-active amino acids: Y122• ↔ [W48?] ↔ Y356 in β2 to Y731 ↔ Y730 ↔ C439 in α2. When 3-aminotyrosine (NH2Y) is incorpora  ...[more]

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