Generation of a stable, aminotyrosyl radical-induced α2ß2 complex of Escherichia coli class Ia ribonucleotide reductase.
Proc Natl Acad Sci U S A
; 110(10): 3835-40, 2013 Mar 05.
Article
en En
| MEDLINE
| ID: mdl-23431160
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 (α2) subunit is transiently oxidized by a stable tyrosyl radical (Yâ¢) in the RNR small (ß2) subunit over a 35-Å pathway of redox-active amino acids Y122⢠â [W48?] â Y356 in ß2 to Y731 â Y730 â C439 in α2. When 3-aminotyrosine (NH2Y) is incorporated in place of Y730, a long-lived NH2Y730⢠is generated in α2 in the presence of wild-type (wt)-ß2, 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 α2ß2 complex. Under conditions that generate NH2Y730â¢, binding between Y730NH2Y-α2 and wt-ß2 is 25-fold tighter (Kd = 7 nM) than for wt-α2
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Ribonucleótido Reductasas
/
Proteínas de Escherichia coli
/
Escherichia coli
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2013
Tipo del documento:
Article
País de afiliación:
Estados Unidos