Crystal structural studies of changes in the native dinuclear iron center of ribonucleotide reductase protein R2 from mouse

Kari R. Strand, Solveig Karlsen, Matthias Kolberg, Åsmund Kjendseth Røhr, Carl Henrik Görbitz, K. Kristoffer Andersson

Research output: Contribution to journalArticle

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Abstract

Class I ribonucleotide reductase (RNR) catalyzes the de nova 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 μ-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 μ-(η1, η2) 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 non-radical diferric B2 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 R2 the lower affinity and cooperative binding of iron in mouse R2.

Original languageEnglish (US)
Pages (from-to)46794-46801
Number of pages8
JournalJournal of Biological Chemistry
Volume279
Issue number45
DOIs
StatePublished - Nov 5 2004

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Ribonucleotide Reductases
Iron
Crystals
Proteins
Escherichia coli
Water
Crystal structure
Deoxyribonucleotides
Ligands
Water Movements
Mammals
Electron Spin Resonance Spectroscopy
Phenylalanine
Conformations
Acetates
Chemical activation
Ions
Molecules

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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Crystal structural studies of changes in the native dinuclear iron center of ribonucleotide reductase protein R2 from mouse. / Strand, Kari R.; Karlsen, Solveig; Kolberg, Matthias; Røhr, Åsmund Kjendseth; Görbitz, Carl Henrik; Andersson, K. Kristoffer.

In: Journal of Biological Chemistry, Vol. 279, No. 45, 05.11.2004, p. 46794-46801.

Research output: Contribution to journalArticle

Strand, Kari R. ; Karlsen, Solveig ; Kolberg, Matthias ; Røhr, Åsmund Kjendseth ; Görbitz, Carl Henrik ; Andersson, K. Kristoffer. / Crystal structural studies of changes in the native dinuclear iron center of ribonucleotide reductase protein R2 from mouse. In: Journal of Biological Chemistry. 2004 ; Vol. 279, No. 45. pp. 46794-46801.
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