Table 1.
Wild-type and mutant MNEI crystallization and X-ray crystallographic data collection, refinement, and model statistics
| WT-MNEI | G16A-MNEI | V37A-MNEI | G16A/V37A-MNEI | |
| [Protein] (mg/ml) | 7.6 | 6.6 | 7 | 8.8 |
| Crystallization conditionsa | 200 mM (NH4)2SO4 and 30% w/v PEG4000 | 3.6 M sodium formate and 10% v/v glycerol | 0.2 M Li2SO4 0.1M HEPES and 25% w/v PEG4000 | 200 mM NaCl, 100 mM phosphate-citrate and 20% w/v PEG8000 |
| Space group | P21 | P41212 | P1 | P21 |
| High resolution (Å) | 1.15 | 2.0 | 1.8 | 2.4 |
| Unit-cell parameters | ||||
| a, b, c (Å) | 27.1, 66.3, 27.2 | 48.7, 48.7, 114.8 | 29.9, 39.7, 45.2 | 31.4, 144.1, 45.8 |
| α, β, γ (°) | 90.0, 111.6, 90.0 | 90.0, 90.0, 90.0 | 84.9, 80.2, 83.9 | 90.0, 90.9, 90.0 |
| Redundancyb | 3.8 (3.7) | 13.6 (13.7) | 3.5 (3.5) | 7.3 (5.5) |
| Total observations | 178 910 | 135 715 | 62 318 | 122 444 |
| Unique observations (hkl) | 28 254 | 9968 | 17 417 | 16 708 |
| Completeness (%) | 88.5 (88.5) | 100 (100) | 92.8 (89.5) | 98.4 (85.0) |
| Rmerge (%)c | 4.3 (25.4) | 5.5 (23.7) | 7.8 (13.0) | 10.7 (53.1) |
| I/σI (%) | 8.9 (2.7) | 7.6 (1.4) | 17.9 (6.4) | 16.0 (4.3) |
| Solvent content (%) | 32.9 | 58.6 | 53.0 | 52.6 |
| Non-H protein atoms in refinement | 1074 | 863 | 1839 | 3202 |
| Solvent molecules | 143 | 61 | 228 | 203 |
| Rwork (%)d | 13.2 | 23.1 | 17.7 | 18.4 |
| Rfree (%)d | 16.2 | 27.0 | 21.9 | 24.5 |
| Overall B factor (Å2) | 15.6 | 33.8 | 23.6 | 27.8 |
| Ramachandran analysis (%) | ||||
| Favorable | 92.4 | 87.8 | 91.4 | 96.3 |
| Allowed | 7.6 | 12.2 | 8.6 | 3.7 |
| Others | 0 | 0 | 0 | 0 |
| RMS deviations from ideal geometry | ||||
| Bond lengths (Å) | 0.026 | 0.018 | 0.014 | 0.008 |
| Bond angles (°) | 1.99 | 1.66 | 1.46 | 1.04 |
| PDB codes | 2O9U | 3PYJ | 3PXM | 3Q2P |
HEPES, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
a
Crystallization experiments performed as sitting drop (WT-MNEI) or hanging drop (all mutants) vapor diffusion.
b
Values in parenthesis correspond to the highest resolution shell.
c
Rmerge = ΣhΣi|I(h)i − <I(h)>|/ΣhΣiI(h)i, where I(h)i is the ith observation of the intensity of reflection h and <I(h)> is the mean value of all I(h)i.
d
R = Σhkl‖Fobs| − |Fcalc‖/Σ|Fobs|, where |Fobs| and |Fcalc| are the observed and calculated structure factor amplitudes for reflection hkl, applied to the work (Rwork) and test (Rfree) sets, respectively.