1H0N

Cobalt substitution of mouse R2 ribonucleotide reductase to model the reactive diferrous state

1H0N の概要

• エントリーDOI: 10.2210/pdb1h0n/pdb
• 関連するPDBエントリー: 1AFT 1H0O 1XSM
• 分子名称: RIBONUCLEOSIDE-DIPHOSPHATE REDUCTASE, COBALT (II) ION (3 entities in total)
• 機能のキーワード: oxidoreductase, ribonucleotide reductase, dinuclear metal-cluster
• 由来する生物種: MUS MUSCULUS (MOUSE)
• 細胞内の位置: Cytoplasm: P11157
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 45267.41

構造登録者

Strand, K.R.,Karlsen, S.,Andersson, K.K. (登録日: 2002-06-26, 公開日: 2002-07-25, 最終更新日: 2023-12-13)

主引用文献

Strand, K.R.,Karlsen, S.,Andersson, K.K.
Cobalt Substitution of Mouse R2 Ribonucleotide Reductase as a Model for Thereactive Diferrous State. Spectroscopic and Structural Evidence for a Ferromagnetically Coupled Dinuclear Cobalt Cluster
J.Biol.Chem., 277:34229-, 2002

PubMed Abstract: The R2 dimer of mouse ribonucleotide reductase contains a dinuclear iron-oxygen cluster and tyrosyl radical/subunit. The dinuclear diferrous form reacts with dioxygen to generate the tyrosyl radical essential for the catalytic reaction that occurs at the R1 dimer. It is important to understand how the reactivity toward oxygen is related to the crystal structure of the dinuclear cluster. For the mouse R2 protein, no structure has been available with a fully occupied dinuclear metal ion site. A cobalt substitution of mouse R2 was performed to produce a good model for the very air-sensitive diferrous form of the enzyme. X-band EPR and light absorption studies (epsilon(550 nm) = 100 mm(-1) cm(-1)/Co(II)) revealed a strong cooperative binding of cobalt to the dinuclear site. In perpendicular mode EPR, the axial signal from mouse R2 incubated with Co(II) showed a typical S = 3/2 Co(II) signal, and its low intensity indicated that the majority of the Co(II) bound to R2 is magnetically coupled. In parallel mode EPR, a typical integer spin signal (M(s) = +/-3) with g approximately 12 is observed at 3.6 K and 10 K, showing that the two Co(II) ions (S = 3/2) in the dinuclear site are ferromagnetically coupled. We have solved the 2.4 A crystal structure of the Co(II)-substituted R2 with a fully occupied dinuclear cluster. The bridging Co(II) carboxylate ligand Glu-267 adopts an altered orientation compared with its counterpart Glu-238 in Escherichia coli R2. This might be important for proper O(2) activation of the more exposed native diferrous site in mouse R2 compared with E. coli R2.

PubMed: 12087093
DOI: 10.1074/JBC.M203358200

実験手法

X-RAY DIFFRACTION (2.4 Å)