Extended Data Fig. 4: Insights into Pol ε positioning within the S. cerevisiae replisome.

a, Cryo-EM density derived from multi-body refinement (top) and corresponding atomic model (bottom) of the Pol ε non-catalytic module (Pol ε^non-Cat), with the exception of the Dpb2 NTD. b, Representative cryo-EM density (mesh) allowing de novo model building and adjustment of prior structures. c, Pol2-Mcm2 AAA+ domain interface. d, Interactions formed by the Mcm5 winged-helix (WH) domain with Pol ε^non-Cat. The Mcm5 WH is observed to contact regions of Pol2 (dark green) in addition to the Pol2 CysB and Dpb2 OB-fold domains. Interactions depicted in c and d have not been characterised previously. e, Regions of additional cryo-EM density observed for SCF^Dia2-bound replisome complexes on dsDNA, visible at low map contour levels. The crystal structure of the Pol2 catalytic domain (PDB: 4M8O³⁴) has been rigid-body fitted to additional density beside the MCM channel exit. In contrast to previous structures^19,28,35, this positions the Pol2 catalytic domain at the C-tier face of CMG, adjacent to the leading-strand template, in a state that may be important for leading-strand synthesis. Additional unassigned density between Ctf4^SepB, Tof1 and SCF^Dia2 is outlined. f, Focused view of additional density attributed to the Pol2 catalytic domain (as in e, except rotated 180°). The C-terminal residue of the Pol2 catalytic domain (residue 1186), the N-terminal residue of the Pol2 non-catalytic domain (residue 1321), and density linking the two domains are indicated.