Table II. Data collection and refinement statistics.
| Statistics | Apo Form (WT-AtPPPS) | Ternary Complex (SM-AtPPPS) |
| Ligands | – | Mg2+/C5-IPSP/C15-FPP |
| Data collection | ||
| Space group | F222 | P61 |
| Unit cell dimensions (Å) | ||
| a | 148.51 | 115.96 |
| b | 150.13 | 115.96 |
| c | 176.11 | 385.87 |
| Resolution (Å)a | 30.00-2.60 (2.69-2.60) | 30.00-2.65 (2.74-2.65) |
| No. of unique reflectionsa | 30,232 (2,979) | 83,662 (8,206) |
| Redundancya | 3.9 (3.5) | 3.7 (2.6) |
| Completeness (%)a | 99.5 (98.8) | 98.8 (97.4) |
| Average I/σ(I)a | 18.3 (2.5) | 28.3 (2.1) |
| Rmerge (%)ab | 7.1 (48.9) | 4.8 (49.5) |
| Refinement | ||
| No. of reflectionsc | 28,230 | 79,172 |
| Rwork/Rfree (%)de | 20.6/25.6 | 22.2/27.4 |
| r.m.s. deviationsf | ||
| Bond lengths (Å) | 0.015 | 0.011 |
| Bond angles (°) | 1.685 | 1.472 |
| B value (Å2)/no. of atoms | ||
| Protein | 48.0/4,586 | 32.2/19,484 |
| Ligand/ion | – | 47.9/248 |
| Water | 53.5/373 | 47.8/721 |
| Ramachandran plot (%)g | ||
| Most favored regions | 93.1 | 92.8 |
| Allowed regions | 6.5 | 6.4 |
| Generously allowed | 0.4 | 0.7 |
| Disallowed | 0 | 0.1 |
Values in parentheses correspond to the highest resolution data shell.
Rmerge = ∑∑I(h)j − <I(h)>/∑∑I(h)j, where I(h)j is the measured diffraction intensity and the summation includes all observations.
All positive reflections were used in the refinement.
Rwork is the R factor = (∑|Fo| − ∑|Fc|)/∑|Fo|, where Fo and Fc are observed and calculated structure factors, respectively.
Rfree is the R factor calculated using 5% of the data that were excluded from the refinement.
The r.m.s. deviation is the root mean square deviation from ideal geometry of protein.
Ramachandran plots were generated with PROCHECK (Laskowski et al., 1993). For the ternary complex of SM-AtPPPS, three residues, Asn-123 (chain D), Leu-30 (chain D), and Leu-30 (chain F), are located in the disallowed region.