Table 1.

Crystallographic data and refinement statistics.

Crystals	M1	M1	M2	M3	M4
Growth conditions	PEG1000	MPD	MPD	MPD	PEG1000
Soaking	Soaked with isopropanol	No	No	No	Soaked with isopropanol
Data collection
Space group	P212121	P212121	P212121	P212121	P212121
Cell dimensions
a, b, c (Å)	74.7, 130.0, 146.4	75.5, 133.0, 147.5	75.6, 132.9, 146.8	76.7, 130.9, 146.4	74.3, 129.5, 146.1
α, β, γ (°)	90, 90, 90	90, 90, 90	90, 90, 90	90, 90, 90	90, 90, 90
Resolution (Å)a	66.5 – 3.14 (3.22 – 3.14)	67.2 – 3.14 (3.22 – 3.14)	64.2 – 3.70 (3.8 – 3.70)	66.1 – 3.95 (4.06 – 3.95)	63.6 – 2.80 (2.87 – 2.80)
Rmeas (%)b	9.5 (90.6)	11.9 (60.0)	7.4 (104.4)	9.8 (133.3)	9.9 (175.7)
Rp.i.m.(%)b	2.7 (24.2)	3.6 (19.9)	3.3 (44.2)	2.9 (36.0)	2.9 (45.4)
I/σ	16.3 (2.98)	12.9 (3.62)	13.0 (1.92)	15.6 (2.09)	15.0 (1.46)
CC1/2	99.6 (89.9)	99.1 (93.9)	99.7 (78.7)	99.9 (86.2)	99.5 (76.0)
Completeness (%)	98.9 (87.9)	95.9 (82.6)	99.5 (96.9)	99.5 (94.4)	99.3 (90.9)
Redundancy	12.9 (11.8)	10.3 (8.1)	5.4 (5.0)	12.9 (12.4)	12.9 (11.3)
Refinement
Resolution (Å)	63.8 – 3.14	67.2 – 3.14	64.2 – 3.70	66.1 – 3.95	63.6 – 2.80
No. of unique reflections	25,212	25,498	16,335	13,323	35,173
% of reflections in test set	10%	10%	10%	10%	5%
Rwork/Rfree	0.211/0.229	0.250/0.270	0.199/.229	0.246/0.266	0.211/0.226
No. of atoms
RNA	6,770	6,776	6,778	6,812	6,746
Mg2+	20	22	23	9	19
K+	0	0	0	0	1

^aValues in parentheses are statistics for the highest resolution bin.

^b

$$\begin{gathered} R_{\mathit{meas}}={\sum }_{\mathit{hkl}}\sqrt{N(\mathit{hkl})/(N(\mathit{hkl})-1)}\times {\sum }_i\mid I_i(\mathit{hkl})-\langle I(\mathit{hkl})\rangle \mid /{\sum }_{\mathit{hkl}}{\sum }_i{I}_i(\mathit{hkl}) \\ {R}_{p.i.m.}={\sum }_{\mathit{hkl}}\sqrt{1/(N(\mathit{hkl})-1}\times {\sum }_i\mid I_i(\mathit{hkl})-\langle I(\mathit{hkl})\rangle \mid /{\sum }_{\mathit{hkl}}{\sum }_i{I}_i(\mathit{hkl}) \end{gathered}$$