Extended Data Table 1.

Data collection and refinement statistics

	Crystal 1
Data collection
Space group	P1 21 1
Cell dimensions
a, b, c(Å)	83.5, 101.9, 88.2
α, β, γ (°)	90.0, 106.9, 90.0
Resolution (Å)	50-3.7 (3 .93-3 .70)*
Rsvm or Rmerge	0.165 (0 .621)
I / σI	5.92 (1.55)
Completeness(%)	98.1 (96.7)
Redundancy	4.0 (4.0)
Refinement
Resolution (Å)	46.12-3.70 (3 .82-3.70)
No. reflections	29885 (2697)
Rwork / Rfree	0.222 (0.333) / 0.285 (0.401)
No. atoms
Protein	19179
Ligand/ion
Water
B-factors
Protein	92.3
Ligand/ion
Water
R.m.s. deviations
Bond lengths (Å)	0.009
Bond angles (°)	1.6

^*Values in parentheses are for highest-resolution shell.