1r65
From Proteopedia
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caption="1r65, resolution 1.95Å" /> | caption="1r65, resolution 1.95Å" /> | ||
'''Crystal structure of ferrous soaked Ribonucleotide Reductase R2 subunit (wildtype) at pH 5 from E. coli'''<br /> | '''Crystal structure of ferrous soaked Ribonucleotide Reductase R2 subunit (wildtype) at pH 5 from E. coli'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The R2 subunit of Escherichia coli ribonucleotide reductase contains a | + | The R2 subunit of Escherichia coli ribonucleotide reductase contains a dinuclear iron center that generates a catalytically essential stable tyrosyl radical by one electron oxidation of a nearby tyrosine residue. After acquisition of Fe(II) ions by the apo protein, the resulting diiron(II) center reacts with O(2) to initiate formation of the radical. Knowledge of the structure of the reactant diiron(II) form of R2 is a prerequisite for a detailed understanding of the O(2) activation mechanism. Whereas kinetic and spectroscopic studies of the reaction have generally been conducted at pH 7.6 with reactant produced by the addition of Fe(II) ions to the apo protein, the available crystal structures of diferrous R2 have been obtained by chemical or photoreduction of the oxidized diiron(III) protein at pH 5-6. To address this discrepancy, we have generated the diiron(II) states of wildtype R2 (R2-wt), R2-D84E, and R2-D84E/W48F by infusion of Fe(II) ions into crystals of the apo proteins at neutral pH. The structures of diferrous R2-wt and R2-D48E determined from these crystals reveal diiron(II) centers with active site geometries that differ significantly from those observed in either chemically or photoreduced crystals. Structures of R2-wt and R2-D48E/W48F determined at both neutral and low pH are very similar, suggesting that the differences are not due solely to pH effects. The structures of these "ferrous soaked" forms are more consistent with circular dichroism (CD) and magnetic circular dichroism (MCD) spectroscopic data and provide alternate starting points for consideration of possible O(2) activation mechanisms. |
==About this Structure== | ==About this Structure== | ||
| - | 1R65 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with FE2 and HG as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonucleoside-diphosphate_reductase Ribonucleoside-diphosphate reductase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.17.4.1 1.17.4.1] Full crystallographic information is available from [http:// | + | 1R65 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=FE2:'>FE2</scene> and <scene name='pdbligand=HG:'>HG</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonucleoside-diphosphate_reductase Ribonucleoside-diphosphate reductase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.17.4.1 1.17.4.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1R65 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Baldwin, J.]] | [[Category: Baldwin, J.]] | ||
| - | [[Category: Jr., J | + | [[Category: Jr., J M.Bollinger.]] |
| - | [[Category: Rosenzweig, A | + | [[Category: Rosenzweig, A C.]] |
[[Category: Saleh, L.]] | [[Category: Saleh, L.]] | ||
[[Category: Sommerhalter, M.]] | [[Category: Sommerhalter, M.]] | ||
| - | [[Category: Voegtli, W | + | [[Category: Voegtli, W C.]] |
[[Category: FE2]] | [[Category: FE2]] | ||
[[Category: HG]] | [[Category: HG]] | ||
[[Category: oxidoreductase]] | [[Category: oxidoreductase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:47:36 2008'' |
Revision as of 12:47, 21 February 2008
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Crystal structure of ferrous soaked Ribonucleotide Reductase R2 subunit (wildtype) at pH 5 from E. coli
Overview
The R2 subunit of Escherichia coli ribonucleotide reductase contains a dinuclear iron center that generates a catalytically essential stable tyrosyl radical by one electron oxidation of a nearby tyrosine residue. After acquisition of Fe(II) ions by the apo protein, the resulting diiron(II) center reacts with O(2) to initiate formation of the radical. Knowledge of the structure of the reactant diiron(II) form of R2 is a prerequisite for a detailed understanding of the O(2) activation mechanism. Whereas kinetic and spectroscopic studies of the reaction have generally been conducted at pH 7.6 with reactant produced by the addition of Fe(II) ions to the apo protein, the available crystal structures of diferrous R2 have been obtained by chemical or photoreduction of the oxidized diiron(III) protein at pH 5-6. To address this discrepancy, we have generated the diiron(II) states of wildtype R2 (R2-wt), R2-D84E, and R2-D84E/W48F by infusion of Fe(II) ions into crystals of the apo proteins at neutral pH. The structures of diferrous R2-wt and R2-D48E determined from these crystals reveal diiron(II) centers with active site geometries that differ significantly from those observed in either chemically or photoreduced crystals. Structures of R2-wt and R2-D48E/W48F determined at both neutral and low pH are very similar, suggesting that the differences are not due solely to pH effects. The structures of these "ferrous soaked" forms are more consistent with circular dichroism (CD) and magnetic circular dichroism (MCD) spectroscopic data and provide alternate starting points for consideration of possible O(2) activation mechanisms.
About this Structure
1R65 is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Ribonucleoside-diphosphate reductase, with EC number 1.17.4.1 Full crystallographic information is available from OCA.
Reference
Variable coordination geometries at the diiron(II) active site of ribonucleotide reductase R2., Voegtli WC, Sommerhalter M, Saleh L, Baldwin J, Bollinger JM Jr, Rosenzweig AC, J Am Chem Soc. 2003 Dec 24;125(51):15822-30. PMID:14677973
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