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| - | [[Image:1yfd.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1yfd| PDB=1yfd | SCENE= }} | | {{STRUCTURE_1yfd| PDB=1yfd | SCENE= }} |
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| - | '''Crystal structure of the Y122H mutant of ribonucleotide reductase R2 protein from E. coli'''
| + | ===Crystal structure of the Y122H mutant of ribonucleotide reductase R2 protein from E. coli=== |
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| - | ==Overview==
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| - | The R2 protein subunit of class I ribonucleotide reductase (RNR) belongs to a structurally related family of oxygen bridged diiron proteins. In wild-type R2 of Escherichia coli, reductive cleavage of molecular oxygen by the diferrous iron center generates a radical on a nearby tyrosine residue (Tyr122), which is essential for the enzymatic activity of RNR, converting ribonucleotides into deoxyribonucleotides. In this work, we characterize the mutant E. coli protein R2-Y122H, where the radical site is substituted with a histidine residue. The x-ray structure verifies the mutation. R2-Y122H contains a novel stable paramagnetic center which we name H, and which we have previously proposed to be a diferric iron center with a strongly coupled radical, Fe(III)Fe(III)R.. Here we report a detailed characterization of center H, using 1H/2H -14N/15N- and 57Fe-ENDOR in comparison with the Fe(III)Fe(IV) intermediate X observed in the iron reconstitution reaction of R2. Specific deuterium labeling of phenylalanine residues reveals that the radical results from a phenylalanine. As Phe208 is the only phenylalanine in the ligand sphere of the iron site, and generation of a phenyl radical requires a very high oxidation potential, we propose that in Y122H residue Phe208 is hydroxylated, as observed earlier in another mutant (R2-Y122F/E238A), and further oxidized to a phenoxyl radical, which is coordinated to Fe1. This work demonstrates that small structural changes can redirect the reactivity of the diiron site, leading to oxygenation of a hydrocarbon, as observed in the structurally similar methane monoxygenase, and beyond, to formation of a stable iron-coordinated radical. | + | The line below this paragraph, {{ABSTRACT_PUBMED_15634667}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15634667 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15634667}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Sjoeberg, B M.]] | | [[Category: Sjoeberg, B M.]] |
| | [[Category: Di-iron center]] | | [[Category: Di-iron center]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:15:10 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 11:23:50 2008'' |
Revision as of 08:23, 28 July 2008
Template:STRUCTURE 1yfd
Crystal structure of the Y122H mutant of ribonucleotide reductase R2 protein from E. coli
Template:ABSTRACT PUBMED 15634667
About this Structure
1YFD is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
A new tyrosyl radical on Phe208 as ligand to the diiron center in Escherichia coli ribonucleotide reductase, mutant R2-Y122H. Combined x-ray diffraction and EPR/ENDOR studies., Kolberg M, Logan DT, Bleifuss G, Potsch S, Sjoberg BM, Graslund A, Lubitz W, Lassmann G, Lendzian F, J Biol Chem. 2005 Mar 25;280(12):11233-46. Epub 2005 Jan 5. PMID:15634667
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