Figure 2. Structure of the BcR2b-NrdI complex.
(A) Structure of the BcR2bMnMn–NrdIox complex (PDB ID: 7Z3D). In each 1:1 R2b–NrdI dimer, R2b and NrdI are coloured in lighter and darker grey, respectively. The second dimer is generated by crystal symmetry. Manganese ions are represented as purple spheres and flavin mononucleotide as yellow sticks at the R2b–NrdI interface. (B) Superimposition of all structures of the BcR2b–NrdI dimer with their corresponding Cα-RMSD in the table. Individual structures are colour coded identically in the figure and the table. Visible N-termini are marked with an arrow (►) and C-termini with a square (◼).
Figure 2—figure supplement 1. Crystallization of the di-manganese BcR2b–NrdI complex.
Spontaneous nucleation yields crystals of the length of 100 µm or longer. In the batch crystallization, crystals are significantly smaller with most crystals between 20 and 50 µm. For the two pictures on the left side, crystals of the complex with NrdI in the oxidized state are viewed under an optical microscope. On the right side, pictures are shown for the complex in solution (top row) and in crystals (bottom row) with NrdI in the oxidized, semiquinone and hydroquinone states. The oxidation state of flavin mononucleotide changes the colour of the complex in both solution and crystals. The semiquinone state is produced by adding sodium dithionite in increments to solutions or crystals.
Figure 2—figure supplement 2. Extended C-terminus of R2b in BcR2bMnMn–NrdIox.
Superposition of BcR2bFeFe–NrdI-1 (PDB ID: 4BMO) (pale green for R2b and grey for NrdI) and BcR2bMnMn–NrdIox (in cyan) showing an extension of the ordered C-terminus of R2b by nine amino acids. The green arrow points towards the C-terminus of BcR2bFeFe–NrdI-1. The C-terminus is situated in a groove between R2b and NrdI; hydrogen bonds are shown with black dashed lines and bonded side chains are shown as sticks.