Table 1.

Cryo-EM refinement parameters and model validation.

	FA CHI	FA-CP CHI	FA-CP POST
Map refinement
Number of particles	178 679	303 005	40 800
Map resolution, half-map FSC0.143 [Å]	2.49	2.02	2.44
Model statistics
Model composition
Total non-hydrogen atoms	146 593	149 701	149 413
RNA residues	4585	4585	4645
Protein residues	6091	6091	6103
Waters	0	3169	1619
Mg ions	169	169	145
General
Map-model FSC0.5 [Å]	2.5	2	2.4
Map-model CCmask	0.89	0.88	0.9
MolProbity score	1.25	1.26	1.26
Clash score	2.89	3.46	2.82
RMSD bond length [Å]	0.005	0.004	0.006
RMSD bond angles [°]	0.633	0.632	0.682
Mean B-factor (protein/nucleotide/ligand/water)	70.7/74.1/51.2/-	40.9/35.1/19.7/8.4	56.9/61.8/40.8/38.9
Protein geometry
Rotamer outliers [%]	1.05	0.99	1.24
Cß deviations > 0.25 Å [%]	0	0	0
Ramachandran [%] (Fav./Allow./Outl.)	97.1/2.9/0.02	97.3/2.7/0.02	97.4/2.6/0.03
Rama-Z (whole/helix/sheet/loop)	0.05/0.88/-0.20/-0.38	0.78/1.80/-0.12/-0.04	0.76/1.74/-0.17/0.00
CaBLAM [%] (Outl./Disf.)	0.98/5.14	0.92/5.31	1.00/5.07
CA Geometry outliers [%]	0.46	0.49	0.51
EMRinger score	4.21	5.48	4.32
Nucleic acid geometry
Backbone bond length outliers [%]	0	0	0
Backbone bond angle outliers [%]	0	0	0
Sugar puckers outliers [%]	0.48	0.50	0.43
Backbone bond torsion suite outliers [%]	11.9	11.9	12.8