Fig. 6: Single-point mutations in POPS are sufficient to cause replication defects and GCR increase.

a POPS mutants, but not pol2-4, are synthetically sick with dpb2-1 and pol32∆. Representative tetrads from diploids of indicated genotypes are shown (more tetrads in Supplementary Fig. 6a). b pol2-R567C leads to reduced replication initiation and progression. Experiments were performed, and data are represented as in Fig. 1e. A represented gel and its quantification are shown. c pol2-R567C increases GCR rates. Experiments were performed, and data are represented as in Fig. 5d. Two-tailed Mann–Whitney tests were performed for statistical analysis. ***p < 0.001. Error bars indicate 95% confidence intervals. Data are presented as median rates of at least seven cultures from two biological replicates per genotype. d A proposed model for dynamic roles of the Pol2 catalytic core and its POPS during genome replication. Briefly, our data suggest that POPS enables efficient Pol ε incorporation into the pre-LC and consequently promotes CMG formation and replication initiation; once replication initiates, POPS supports optimal DNA polymerization activity and ability to overcome template barriers. POPS mutations as seen in cancer cells can lead to reduced CMG formation and replication initiation, as well as poor replication progression, resulting in increased genome rearrangements (see text for details).