Table 1.

Data collection and refinement statistics

Space group	P1	P31
Cell dimensions (Å) (°)	a = 27.9	a = 49.7
	b = 28.5	b = 49.7
	c = 37.2	c = 36.5
	α = 107.4	α = 90.0
	β = 96.9	β = 90.0
	γ = 104.6	γ = 120.0
Molecules/asymmetric unit	2	2
Resolution (Å)	1.8	2.0
Completeness (%)	94.0	99.7
Observed reflections	33871	24299
Unique reflections	9025	6795
Rmergea (%)	7.2	6.9
R-factorb (%)	20.2	18.9
R-free (%)	23.3	23.5
Number of protein atoms	970	963
Number of water molecules	94	92
Average B-value (Å2)
overall	20.8	24.6
main chain	19.2	23.9
side chain	22.3	25.4
R.m.s.d. bond lengths (Å)	0.007	0.016
R.m.s.d. bond angles (°)	1.38	1.85

^a R_merge = ∑|I_i − 〈I〉| Σ 〈I〉.

^bR-factor = ∑|F_o = F_c|/∑F_o.