Table 1

Statistics for data collection, phase determination, and model construction. HA, heavy-atom concentration; ST, soaking time; Res, resolution; λ, wavelength; Obs, observations; Redun, redundancy; Compl, completeness; (*) last-resolution shell.R iso: Σ|F PHF P|/F PH, whereF PH and F P are the derivative and the native structure factor amplitudes, respectively.R sym: ΣΣi|I (h)iI (h)i|/ΣΣ:I (h)i, whereI (h) is the mean intensity after reflections. Phasing power: rms isomorphous difference divided by the rms residual lack of closure.R cullis: Σ(∥F PHF P| − |F H(calc)∥)/Σ|F PHF P|, where F PH is the structure factor of the derivative and F P is that of the native data. The summation is valid only for centric reflection. FOM (figure of merit): mean value of the cosine of the error in phase angles. Abbreviations: MIRAS, multiple isomorphous replacement, anomalous scattering; SAD, single wavelength anomalous diffraction.

Data statistics
HA (mM)30.00.520.04.53.0
ST (hours)1.5424 hours24 hours24 hours
Sites no.1322084389
Res (Å)90–2.440–3.540–3.830–2.930–3.230–3.530–3.8
λ (Å)
Redun (*)9.1 (6.5)3.0 (2.5)1.9 (1.6) (4.2)3.7
Compl (*)95.6 (71.0)99.4 (96.8)92.0 (54.1)97.193.898.1 (99.0)99.5
II (*)25.5 (1.9)13.5 (3.3)8.9 (1.6)18.0 (6.4)12.0 (2.6)10.6 (2.7)10.8 (3.2)
Rmerge (*)8.6 (69.1)7.2 (32.0)9.1 (37.9)11.2 (36.9)8.5 (29.5)12.1 (46.0)12.1 (40.5)
χ2 (ano) (*)2.8 (1.0)1.5 (1.0)2.63 (1.48)1.8 (1.0)2.42 (1.18)
Riso(*)14.1 (22.7)26.4 (47.0)12.9 (28.1)19.5 (39.4)
Phasing statistics
Resolution shells (Å): ∼73,200 reflections per bin
MIRAS1 (FOM)0.520.310.140.32
Os(NH3)5 2+
Phasing power0.870.720.660.75
Phasing power (SAD)1.400.580.260.75
UO2F5 3−
Phasing power0.470.330.280.36
Phasing power (SAD)0.460.250.36
MIRAS2 (FOM)0.480.400.280.120.33
Ir(NH3)6 3+
Phasing power1.020.920.780.660.89
Phasing power (SAD)2.021.601.220.831.47
Os(NH3)6 3+
Phasing power0.620.570.580.580.59
Phasing power (SAD)0.470.390.42
Ta6Br12 2+(used for SAD phasing only)
Phasing power (SAD)2.770.350.131.19
FOM(MIRAS1+MIRAS2+SAD) 0.760.510.310.140.37
Model statistics
Resolution range (Å)90.0–2.4rms deviations:Average B factors (Å2)
Reflections577,304Bonds (Å)0.0064 All atoms 37.4
Rcryst(%)25.2Angles (°)1.19 23SrRNA32.3
Rfree (%)26.1Dihedrals (°)28.8 5S rRNA43.2
Impropers (°)1.68Minimum/Max B factors (Å2)7.0/107.9