Extended Data Table 1 |.

X-Ray Data Collection and Structure Refinement Statistics

	Apo CAPP	dGTP complex	Post-catalytic complex	Primer initiation complex	Primer initiation complex (alternate)
Deposition ID (PDB)	7NQD	7NQE	7NQF	7P9J	7QAZ
Data Collection
Wavelength (Å)	0.97624	0.97625	0.91589	0.97950	0.97950
Space group	P 65	P 21 21 21	P21212	P 21 21 21	P 21 21 21
Cell parameters
a, b, c (Å)	97.4, 97.4, 109.0	40.0, 62.7, 82.5	77.0, 160.4, 39.8	227.8, 39.5, 75.0	227.9, 39.6, 79.8
α, β, γ (°)	90, 90, 120	90, 90, 90	90, 90, 90	90, 90, 90	90, 90, 90
Resolution limits (Å)	45.79 – 2.97	49.90 – 1.28	80.18 – 2.02	45.35 – 1.90	56.98 – 2.11
(high-resolution bin)*	(3.02 – 2.97)	(1.33 – 1.28)	(2.06 – 2.02)	(1.93 – 1.90)	(2.15 – 2.11)
Completeness (%)	100.00 (99.67)	99.20 (90.64)	99.8 (99.9)	76.4 (78.2)	94.4 (69.6)
Multiplicity	6.75 (6.88)	5.90 (3.52)	4.3 (4.4)	2.5 (2.1)	3.8 (1.9)
CC-half	0.9924 (0.3348)	0.9987 (0.2840)	0.995 (0.321)	0.997 (0.282)	0.992 (0.298)
l/sigma	8.55 (1.01)	9.58 (1.00)	5.6 (0.7)	7.7 (0.5)	6.5 (0.6)
Rmerge	0.2191 (1.7515)	0.0805 (1.6421)	0.159 (1.986)	0.070 (1.373)	0.151 (1.042)
Refinement
Protein monomers per asymmetric unit	2	1	2	3	3
Total nonhydrogen atoms	3375	2198	4268	5813	6224
Water molecules	0	191	141	154	395
Rcryst (%)	21.60	16.29	21.21	22.75	20.97
Rfree (%)	23.99	19.01	25.93	25.90	26.08
Ramachandran analysis (%)
Most favoured	96.34	97.70	97.89	97.21	97.38
Outliers	0.24	0	0	0.16	0
Rmsds
Bonds (Å)	0.003	0.006	0.008	0.009	0.007
Angles (°)	0.620	1.007	0.942	1.347	0.979
Planes (Å)	0.004	0.007	0.008	0.008	0.007
Mean atomic b value (Å2)	79.50	14.19	34.34	37.49	31.36

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