Table S1.
Data collection and refinement statistics*
| Mg formate | Tris | Mes | |
| Data collection | |||
| Space group | P61 | P21 | P61 |
| Cell dimensions | |||
| a, b, c, Å | 154.9, 154.9, 118.4 | 151.9, 118.6, 151.9 | 153.9, 153.9, 116.5 |
| α, β, γ, ° | 90, 90, 120 | 90, 118.6, 90 | 90, 90, 120 |
| Resolution, Å | 50–2.5 | 50–2.15 | 50–2.9 |
| CC1/2, %† | 98.8 (11.4) | 98 (10.1) | 99.6 (13) |
| Rmerge‡ | 19 (211) | 17.6 (199) | 9.3 (168) |
| I/σ, I | 6.2 (0.45) | 5.2 (0.47) | 9.47 (0.47) |
| Completeness, % | 99.5 (96.3) | 70.5 (34.7) | 97.8 (85.3) |
| Redundancy, % | 5.2 (2.8) | 2.8 (1.9) | 3.11 (1.88) |
| Refinement | |||
| Resolution, Å | 50–2.5 | 50–2.15 | 50–2.9 |
| No. reflections, total/unique | 282,303 (54,239) | 510,372 (180,557) | 105,809 (33,986) |
| % Rwork§/Rfree¶ | 17.9/22.5 | 19.4/23.4 | 19.3/22.9 |
| No. atoms | |||
| Protein | 8,081 | 24,146 | 7,997 |
| Ion | 7 | 18 | 5 |
| Water | 654 | 2,052 | 206 |
| B factors | |||
| Protein | 53 | 38 | 85 |
| Ion | 44 | 48 | 92 |
| Water | 51 | 39 | 71 |
| Mol/asym unit | 1 | 3 | 1 |
| Ramachandran, %# | 96.1, 3.7, 0.2 | 95.7, 4.0, 0.3 | 94.7, 4.8, 0.5 |
| MolProbity score | 1.67 (99%) | 1.74 (94%) | 1.78 (100%) |
| MolProbity ClashScore | 5.6 (99%) | 5.24 (97%) | 4.85 (100%) |
| rmsd | |||
| Bond lengths, Å | 0.007 | 0.004 | 0.012 |
| Bond angles, ° | 0.762 | 0.800 | 0.788 |
| PDB ID code | 5E6U | 5E6S | 5E6R |
Numbers in parentheses correspond to the outermost resolution shell.
CC1/2, Pearson’s correlation coefficient between average intensities of random half-datasets for each unique reflection (37).
Rmerge = ΣhklΣi|Ii(hkl) − 〈Ī(hkl)〉|/ΣhklΣiIi(hkl), where Ii(hkl) and 〈I(hkl))〉 are the ith and mean measurement of the intensity of reflection hkl.
Rwork = Σhkl||Fobs(hkl)| − |Fcalc(hkl)||/Σhkl|Fobs(hkl)|, where Fobs(hkl) and Fcalc(hkl) are the observed and calculated structure factors, respectively. No I/σ cutoff was applied.
Rfree is the R value obtained for a test set of reflections consisting of a randomly selected ∼5% subset of the dataset excluded from refinement.
Residues in favored, accepted, and outlier regions of the Ramachandran plot as reported by MolProbity (36).