A 2.8 A Fe-Fe separation in the Fe2(III/IV) intermediate, X, from Escherichia coli ribonucleotide reductase.

ABSTRACT: A class Ia ribonucleotide reductase (RNR) employs a μ-oxo-Fe2(III/III)/tyrosyl radical cofactor in its β subunit to oxidize a cysteine residue ~35 Å away in its α subunit; the resultant cysteine radical initiates substrate reduction. During self-assembly of the Escherichia coli RNR-β cofactor, reaction of the protein's Fe2(II/II) complex with O2 results in accumulation of an Fe2(III/IV) cluster, termed X, which oxidizes the adjacent tyrosine (Y122) to the radical (Y122(•)) as the cluster is converted to the μ-oxo-Fe2(III/III) product. As the first high-valent non-heme-iron enzyme complex to be identified and the key activating intermediate of class Ia RNRs, X has been the focus of intensive efforts to determine its structure. Initial characterization by extended X-ray absorption fine struc

SUBMITTER: Dassama LM 

PROVIDER: S-EPMC4209742 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature