Fig. 2: Structures of the pol ι product complexes.

(A) Close-up of the active site of the pol ι complex with pyrophosphate bound and with the newly formed base pair labeled n, the primer-terminal base pair labeled n-1, and the base on the 5′ side of the template base labeled n + 1 and with a polder map contoured at σ = 3.0 around the pyrophosphate (green mesh). (B) Overlay of the DNA and dTTP substrates of the pol ι-DNA-dTTP ternary complex (white) and the DNA of the pol ι complex with pyrophosphate bound (yellow). The distances moved by the α-phosphate of the dTTP, the 3′ oxygen of the primer terminus, and the two metal ions is indicated. (C) Close-up of the active sites of the pol ι complex with two monophosphate products bound and with the newly formed base pair labeled n, the primer-terminal base pair labeled n-1, and the base on the 5′ side of the template base labeled n + 1 and with a polder map contoured at σ = 3.0 around the two monophosphates (green mesh). The conclusion that the electron density shown here corresponds to monophosphates rather than water molecules is supported by observing an increase in R-free when modeling water molecules. (D) Graph showing the production of monophosphate by pol ι in the presence of DNA and dTTP. Data are presented as mean values ± SEM. Four technical replicates of each experimental condition were carried out. Source data are provided as a Source Data file. The p values were derived from one-way ANOVA using GraphPad Prism, and **** indicates p < 0.0001.