|
|
| Line 1: |
Line 1: |
| [[Image:1yfd.gif|left|200px]] | | {{Seed}} |
| | [[Image:1yfd.png|left|200px]] |
|
| |
|
| <!-- | | <!-- |
| Line 9: |
Line 10: |
| {{STRUCTURE_1yfd| PDB=1yfd | SCENE= }} | | {{STRUCTURE_1yfd| PDB=1yfd | SCENE= }} |
|
| |
|
| '''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=== |
|
| |
|
|
| |
|
| ==Overview==
| | <!-- |
| 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. |
| | --> |
| | {{ABSTRACT_PUBMED_15634667}} |
|
| |
|
| ==About this Structure== | | ==About this Structure== |
| Line 33: |
Line 37: |
| [[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'' |