3n38

Publication Abstract from PubMed

The class Ib ribonucleotide reductase of Escherichia coli can initiate reduction of nucleotides to deoxynucleotides with either a Mn(III)(2)-tyrosyl radical (Y*) or a Fe(III)(2)-Y* cofactor in the NrdF subunit. Whereas Fe(III)(2)-Y* can self-assemble from Fe(II)(2)-NrdF and O(2), activation of Mn(II)(2)-NrdF requires a reduced flavoprotein, NrdI, proposed to form the oxidant for cofactor assembly by reduction of O(2). The crystal structures reported here of E. coli Mn(II)(2)-NrdF and Fe(II)(2)-NrdF reveal different coordination environments, suggesting distinct initial binding sites for the oxidants during cofactor activation. In the structures of Mn(II)(2)-NrdF in complex with reduced and oxidized NrdI, a continuous channel connects the NrdI flavin cofactor to the NrdF Mn(II)(2) active site. Crystallographic detection of a putative peroxide in this channel supports the proposed mechanism of Mn(III)(2)-Y* cofactor assembly.

Structural Basis for Activation of Class Ib Ribonucleotide Reductase.,Boal AK, Cotruvo JA Jr, Stubbe J, Rosenzweig AC Science. 2010 Aug 5. PMID:20688982^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.