• ribonucleotide reductase R2;
  • diiron center;
  • dimanganese center;
  • crystal contacts.

A new crystal form of wild-type ribonucleotide reductase R2 from Escherichia coli was obtained. Crystals grow in space group P6122 with one R2 monomer in the asymmetric unit. A twofold crystallographic symmetry axis generates the physiological dimeric form of R2. Co-crystallization with CoCl2 or MnCl2 results in full occupancy of the dinuclear metal site. The structure of the MnII-loaded form was determined to 2.6 Å resolution by molecular replacement. The crystallization conditions, backbone conformation, crystal-packing interactions and metal centers are compared with those of previously determined crystal forms.