Xiangzhou Meng1,3,4, Clémence Claussin1,4, Gemma Regan-Mochrie1,2,4, Iestyn Whitehouse1 and Xiaolan Zhao1 1Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA; 2Gerstner Sloan Kettering Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA Corresponding authors: zhaox1mskcc.org, whitehouseimskcc.org

↵4 These author contributed equally to this work.

↵3 Present address: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.

Abstract

Pol2 is the leading-strand DNA polymerase in budding yeast. Here we describe an antagonism between its conserved POPS (Pol2 family-specific catalytic core peripheral subdomain) and exonuclease domain and the importance of this antagonism in genome replication. We show that multiple defects caused by POPS mutations, including impaired growth and DNA synthesis, genome instability, and reliance on other genome maintenance factors, were rescued by exonuclease inactivation. Single-molecule data revealed that the rescue stemmed from allowing sister replication forks to progress at equal rates. Our data suggest that balanced activity of Pol2's POPS and exonuclease domains is vital for genome replication and stability.

Received August 26, 2022. Accepted December 19, 2022.