Table 1. Crystallographic statistics.
Values in parentheses refer to the highest resolution bin of approximate width 0.1 Å. Rmerge=ΣhΣi‖(h,i)−<I(h)> ΣhΣi I(h,i). Rwork=Σhkl‖Fo|-|Fc‖/Σ|Fo|, where Fo is the observed structure factor and Fc the calculated structure factor. Rfree is the same as Rwork except calculated using the 5% of the data that are not included in any refinement calculations.
| Parameter | Value |
|---|---|
| Data collection | |
| Space group | I2 |
| Wavelength (Å) | 0.9763 |
| Unit cell parameters | |
| a, b, c, (Å) | 115.5, 122.2, 227.8 |
| β (°) | 95.6 |
| Resolution range (Å) | 29.5–3.2 |
| Unique reflections (n) | 51975 |
| Completeness (%) | 99.6 (98.6) |
| <I/σ(I)> | 9.7 (1.8) |
| Multiplicity | 3.8 (3.8) |
| Rmerge (%) | 10.4 (58.1) |
| Refinement | |
| Resolution range (Å) | 29.5–3.2 |
| Number of used reflections | 49122 |
| Rwork, Rfree | 15.9, 20.6 |
| Protein atoms | 19918 |
| Waters, chlorides, magnesium, sulfates | 114, 7, 3, 2 |
| RMSD from ideal geometry | |
| Bond lengths (Å) | 0.011 |
| Bond angles (°) | 1.523 |
| Thermal parameters (Å2) | |
| Wilson B-factor | 83.8 |
| Mean B-factor | 56.9 |
| Subunit L, S, A, B, C, D | 55.0, 56.5, 59.2, 59.6, 56.0, 59.2 |
| FeS centres (heterodimers: LS, AB and CD) | |
| F4S (proximal 4Fe–3S cluster) | 82.0, 82.1, 82.3 |
| FXS (medial 3Fe–4S cluster) | 52.5, 56.4, 53.1 |
| SFW (distal 4Fe–4S cluster) | 55.75, 52.79, 52.59 |
| NFU ([NiFe] active site) | 53.2, 58.5, 55.7 |
| Magnesium, chlorides, sulfates, water | 49.4, 74.9, 114, 46.6 |
| Ramachandran plot | |
| Favoured, allowed, disallowed (%) | 92.1, 7.6, 0.3 |