Fig. 1: Cryo-EM structure of Pol ε cat bound to DNA and PCNA.
a, Cryo-EM density map of the human Pol ε–DNA–PCNA complex in the open Finger conformation. b, Two views of a ribbon model of Pol ε cat in complex with PCNA, substrate DNA and an incoming nucleotide in the open Finger conformation. In this and subsequent figures, unless otherwise stated, domains are colored as follows: NTD, yellow; Exo domain, orange; Finger domain, teal; Palm domain, light pink; P domain, salmon; Thumb domain, blue; PIP box, dark green. DNA template and nascent strands are shown as magenta and cyan spheres, respectively. c, Contact sites between PCNA and Pol ε are formed by the PIP box motif and Pol ε unique Thumb insert and P domain. The PCNA protomer that interacts with the PIP box is shown in the front in surface representation. Conserved interface residues of the PIP box are shown as sticks and colored by atom type: carbon, as the respective domain or region; nitrogen, blue; oxygen, red. d, Contacts formed by the Thumb insert (blue, left) and P domain (salmon, right) with the adjacent PCNA protomers (PCNAThumb and PCNAP, respectively). Q and hydrophobic pockets of the PCNA protomers (shown in surface representation) are indicated. Rotation symbols in this figure indicate the view relative to c.
