Table 1.
| ecCTLA4 | |
|---|---|
| Data collection | |
| Space group | P3121 |
| Cell dimensions | |
| a, b, c (Å) | 43.0, 43.0, 140.1 |
| α, β, γ (°) | 90, 90, 120 |
| Resolution (Å) | 18.6–2.6 |
| Rmerge | 3.6 (20.0) |
| I/σI | 29.1 (9.0) |
| No. of reflections/no. unique | 99,136/4488 |
| Completeness (%) | 85.0 (45.8) |
| Redundancy | 22.1 (21.3) |
| Refinement | |
| Resolution (Å) | 18.6–2.6 |
| No. of reflections | 4289 |
| Rwork/Rfree | 19.2/24.5⁎ |
| No. of atoms | |
| Protein | 914 |
| Water | 50 |
| B-factors | |
| Protein (main chain) | 26.6 |
| Protein (side chain) | 31.1 |
| Water | 22.1 |
| Overall | 28.4 |
| R.M.S.D.s | |
| Bond lengths (Å) | 0.006 |
| Bond angles (°) | 1.03 |
| Ramachandran plot analysis | |
| Outliers | 0.00% |
| In allowed regions | 4.31% |
| In preferred regions | 95.69% |
The CTLA4 vl-Ig was concentrated to 10 mg/ml in Hepes-buffered saline at pH 7.4 and crystallised in 0.02 M magnesium chloride, 0.1 M Hepes (pH 7.5), 22% (w/v) polyacrylic acid 5100 sodium salt and 0.4 M NDSB-256 (nondetergent sulfobetaine 256, dimethylbenzylammonium propane sulfonate), or with 6% 1,6-diaminohexane. Crystals appeared after 12 h and were frozen in a stream of nitrogen either with perfluorated oil or with 25% glycerol in the mother liquor as cryoprotectant. Data were collected on a MAR345 in-house detector at a wavelength of 1.542 Å. Data were indexed, integrated and scaled with the XDS package21 and the structure was solved by molecular replacement using PHASER22 with monomeric CTLA4 (Protein Data Bank code 1I8L, the structure of CTLA4 from the complex with B7-13). The structure was refined with Refmac5.423 using a maximum likelihood target alternated with manual rebuilding of the structure (⁎4.2% of the reflections have been used for Rfree calculation, i.e., 189 reflections). Parenthetical values are for the highest-resolution shell.