DNA polymerization-independent functions of DNA polymerase epsilon in assembly and progression of the replisome in fission yeast.

ABSTRACT: DNA polymerase epsilon (Pol ?) synthesizes the leading strands, following the CMG (Cdc45, Mcm2-7, and GINS [Go-Ichi-Nii-San]) helicase that translocates on the leading-strand template at eukaryotic replication forks. Although Pol ? is essential for the viability of fission and budding yeasts, the N-terminal polymerase domain of the catalytic subunit, Cdc20/Pol2, is dispensable for viability, leaving the following question: what is the essential role(s) of Pol ?? In this study, we investigated the essential roles of Pol ? using a temperature-sensitive mutant and a recently developed protein-depletion (off-aid) system in fission yeast. In cdc20-ct1 cells carrying mutations in the C-terminal domain of Cdc20, the CMG components, RPA, Pol ?, and Pol ? were loaded onto replication origins, but Cdc45 did not translocate from the origins, suggesting that Pol ? is required for CMG helicase progression. In contrast, depletion of Cdc20 abolished the loading of GINS and Cdc45 onto origins, indicating that Pol ? is essential for assembly of the CMG complex. These results demonstrate that Pol ? plays essential roles in both the assembly and progression of CMG helicase.

SUBMITTER: Handa T 

PROVIDER: S-EPMC3418317 | biostudies-other | 2012 Aug

REPOSITORIES: biostudies-other