1w69

From Proteopedia

Revision as of 08:19, 3 February 2008

CRYSTAL STRUCTURE OF MOUSE RIBONUCLEOTIDE REDUCTASE SUBUNIT R2 UNDER REDUCING CONDITIONS. A FULLY OCCUPIED DINUCLEAR IRON CLUSTER AND BOUND ACETATE.

Overview

Class I ribonucleotide reductase (RNR) catalyzes the de novo synthesis of, deoxyribonucleotides in mammals and many other organisms. The RNR subunit, R2 contains a dinuclear iron center, which in its diferrous form, spontaneously reacts with O2, forming a mu-oxo-bridged diferric cluster, and a stable tyrosyl radical. Here, we present the first crystal, structures of R2 from mouse with its native dinuclear iron center, both, under reducing and oxidizing conditions. In one structure obtained under, reducing conditions, the iron-bridging ligand Glu-267 adopts the, mu-(eta1,eta2) coordination mode, which has previously been related to O2, activation, and an acetate ion from the soaking solution is observed where, O2 has been proposed to bind the iron. The structure of mouse R2 under, oxidizing conditions resembles the nonradical diferric R2 from Escherichia, coli, with the exception of the coordination of water and Asp-139 to Fe1., There are also additional water molecules near the tyrosyl radical site, as suggested by previous spectroscopic studies. Since no crystal structure, of the active radical form has been reported, we propose models for the, movement of waters and/or tyrosyl radical site when diferric R2 is, oxidized to the radical form, in agreement with our previous ENDOR study., Compared with E. coli R2, two conserved phenylalanine residues in the, hydrophobic environment around the diiron center have opposing rotameric, conformations, and the carboxylate ligands of the diiron center in mouse, R2 appear more flexible. Together, this might contribute to the lower, affinity and cooperative binding of iron in mouse R2.

About this Structure

1W69 is a Single protein structure of sequence from Mus musculus with and as ligands. Active as Ribonucleoside-diphosphate reductase, with EC number 1.17.4.1 Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Crystal structural studies of changes in the native dinuclear iron center of ribonucleotide reductase protein R2 from mouse., Strand KR, Karlsen S, Kolberg M, Rohr AK, Gorbitz CH, Andersson KK, J Biol Chem. 2004 Nov 5;279(45):46794-801. Epub 2004 Aug 17. PMID:15322079

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