1RNR

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

Summary for 1RNR

• Entry DOI: 10.2210/pdb1rnr/pdb
• Descriptor: RIBONUCLEOTIDE REDUCTASE R1 PROTEIN, FE (III) ION, MERCURY (II) ION, ... (4 entities in total)
• Functional Keywords: reductase(acting on ch2), oxidoreductase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 89835.26

Authors

Aberg, A.,Nordlund, P. (deposition date: 1993-04-26, release date: 1994-01-31, Last modification date: 2024-11-06)

Primary citation

Aberg, A.,Ormo, M.,Nordlund, P.,Sjoberg, B.M.
Autocatalytic generation of dopa in the engineered protein R2 F208Y from Escherichia coli ribonucleotide reductase and crystal structure of the dopa-208 protein.
Biochemistry, 32:9845-9850, 1993

PubMed 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 [Ormö, M., de Maré, F., Regnström, K., Aberg, A., Sahlin, M., Ling, J., Loehr, T. M., Sanders-Loehr, J., & Sjöberg, 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.

PubMed: 8373782
DOI: 10.1021/bi00088a040

Experimental method

X-RAY DIFFRACTION (2.5 Å)