1RNR: AUTOCATALYTIC GENERATION OF DOPA IN THE ENGINEERED PROTEIN R2 F208Y FROM ESCHERICHIA COLI RIBONUCLEOTIDE REDUCTASE AND CRYSTAL STRUCTURE OF THE DOPA-208 PROTEIN

Citation:
Abstract
The mutant form Phe-208-->Tyr of the R2 protein of Escherichia coli ribonucleotide reductase contains an intrinsic ferric-Dopa cofactor with characteristic absorption bands at 460 and ca. 700 nm [Ormo, M., de Mare, F., Regnstrom, K., Aberg, A., Sahlin, M., Ling, J., Loehr, T. M., Sanders-Loehr, J., & Sjoberg, B. M. (1992) J. Biol. Chem. 267, 8711-8714]. The three-dimensional structure of the mutant protein, solved to 2.5-A resolution, shows that the Dopa is localized to residue 208 and that it is a bidentate ligand of Fe1 of the binuclear iron center of protein R2. Nascent apoR2 F208Y, lacking metal ions, can be purified from overproducing cells grown in iron-depleted medium. ApoR2 F208Y is rapidly and quantitatively converted to the Dopa-208 form in vitro by addition of ferrous iron in the presence of oxygen. Other metal ions (Cu2+, Mn2+, Co2+) known to bind to the metal site of wild-type apoR2 do not generate a Dopa in apoR2 F208Y. The autocatalytic generation of Dopa does not require the presence of a tyrosine residue at position 122, the tyrosine which in a wild-type R2 protein acquires the catalytically essential tyrosyl radical. It is proposed that generation of Dopa initially follows the suggested reaction mechanism for tyrosyl radical generation in the wild-type protein and involves a ferryl intermediate, which in the case of the mutant R2 protein oxygenates Tyr 208. This autocatalytic metal-mediated reaction in the engineered R2 F208Y protein may serve as a model for formation of covalently bound quinones in other proteins.
PDB ID: 1RNRDownload
MMDB ID: 51197
PDB Deposition Date: 1993/4/26
Updated in MMDB: 2017/12
Experimental Method:
x-ray diffraction
Resolution: 2.5  Å
Source Organism:
Similar Structures:
Biological Unit for 1RNR: dimeric; determined by author and by software (PISA)
Molecular Components in 1RNR
Label Count Molecule
Proteins (2 molecules)
2
Ribonucleotide Reductase R1 Protein(Gene symbol: nrdB)
Molecule annotation
Chemicals (18 molecules)
1
4
2
14
* Click molecule labels to explore molecular sequence information.

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