1mxr
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High resolution structure of Ribonucleotide reductase R2 from E. coli in its oxidised (Met) form
OverviewOverview
The R2 protein of class I ribonucleotide reductase generates and stores a, tyrosyl radical essential for ribonucleotide reduction and, thus, DNA, synthesis. X-ray structures of the protein have enabled detailed, mechanistic suggestions, but no structural information has been available, for the active radical-containing state of the protein. Here we report on, methods to generate the functional tyrosyl radical in single crystals of, R2 from Escherichia coli (Y122(*)). We further report on subsequent, high-field EPR experiments on the radical-containing crystals. A full, rotational pattern of the spectra was collected and the orientation of the, g-tensor axes were determined, which directly reflect the orientation of, the radical in the crystal frame. The EPR data are discussed in comparison, with a 1.42-A x-ray structure of the met (oxidized) form of the protein, also presented in this paper. Comparison of the orientation of the radical, Y122(*) obtained from high-field EPR with that of the reduced tyrosine, Y122-OH reveals a significant rotation of the tyrosyl side chain, away, from the diiron center, in the active radical state. Implications for the, radical transfer connecting the diiron site in R2 with the, substrate-binding site in R1 are discussed. In addition, the present study, demonstrates that structural and functional information about active, radical states can be obtained by combined x-ray and high-field EPR, crystallography.
About this StructureAbout this Structure
1MXR is a Single protein structure of sequence from Escherichia coli with FE, HG and GOL as ligands. Active as Ribonucleoside-diphosphate reductase, with EC number 1.17.4.1 Full crystallographic information is available from OCA.
ReferenceReference
Displacement of the tyrosyl radical cofactor in ribonucleotide reductase obtained by single-crystal high-field EPR and 1.4-A x-ray data., Hogbom M, Galander M, Andersson M, Kolberg M, Hofbauer W, Lassmann G, Nordlund P, Lendzian F, Proc Natl Acad Sci U S A. 2003 Mar 18;100(6):3209-14. Epub 2003 Mar 6. PMID:12624184
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