1MRR: SUBSTITUTION OF MANGANESE FOR IRON IN RIBONUCLEOTIDE REDUCTASE FROM ESCHERICHIA COLI. SPECTROSCOPIC AND CRYSTALLOGRAPHIC CHARACTERIZATION

Citation:
Abstract
Each polypeptide chain of protein R2, the small subunit of ribonucleotide reductase from Escherichia coli, contains a stable tyrosyl radical and two antiferromagnetically coupled oxo-bridged ferric ions. A refined structure of R2 has been recently obtained. R2 can be converted into apoR2 by chelating out the metal cofactor and scavenging the radical. This study shows that apoR2 has a very strong affinity for four stable Mn2+ ions. The manganese-containing form of R2, named Mn-R2, has been studied by EPR spectroscopy and x-ray crystallography. It contains two binuclear manganese clusters in which the two manganese ions occupy the natural iron-binding sites and are only bridged by carboxylates from glutamates 115 and 238. This in turn explains why the spin-exchange interaction between the two ions is very weak and why Mn-R2 is EPR active. Mn-R2 could provide a model for the native diferrous form of protein R2, and a detailed molecular mechanism for the reduction of the iron center of protein R2 is proposed.
PDB ID: 1MRRDownload
MMDB ID: 50351
PDB Deposition Date: 1992/7/28
Updated in MMDB: 2017/12
Experimental Method:
x-ray diffraction
Resolution: 2.5  Å
Source Organism:
Similar Structures:
Biological Unit for 1MRR: dimeric; determined by author and by software (PISA)
Molecular Components in 1MRR
Label Count Molecule
Proteins (2 molecules)
2
Ribonucleotide Reductase R1 Protein(Gene symbol: nrdB)
Molecule annotation
Chemicals (17 molecules)
1
4
2
13
* Click molecule labels to explore molecular sequence information.

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