title: The architecture of a eukaryotic replisome.
abstract: At the eukaryotic DNA replication fork, it is widely believed that the Cdc45-Mcm2-7-GINS (CMG) helicase is positioned in front to unwind DNA and that DNA polymerases trail behind the helicase. Here we used single-particle EM to directly image a Saccharomyces cerevisiae replisome. Contrary to expectations, the leading strand Pol ɛ is positioned ahead of CMG helicase, whereas Ctf4 and the lagging-strand polymerase (Pol) α-primase are behind the helicase. This unexpected architecture indicates that the leading-strand DNA travels a long distance before reaching Pol ɛ, first threading through the Mcm2-7 ring and then making a U-turn at the bottom and reaching Pol ɛ at the top of CMG. Our work reveals an unexpected configuration of the eukaryotic replisome, suggests possible reasons for this architecture and provides a basis for further structural and biochemical replisome studies.
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, New York, USA.|Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Jingchuan
authors.initials: J
authors.lastname: Sun
authors.affiliation: DNA Replication Laboratory, Rockefeller University, New York, New York, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Shi
authors.affiliation: DNA Replication Laboratory, Rockefeller University, New York, New York, USA.|Howard Hughes Medical Institute, Rockefeller University, New York, New York, USA.
authors.forename: Roxana E
authors.initials: RE
authors.lastname: Georgescu
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, New York, USA.|Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Zuanning
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: DNA Replication Laboratory, Rockefeller University, New York, New York, USA.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Chait
authors.affiliation: Biosciences Department, Brookhaven National Laboratory, Upton, New York, USA.|Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
authors.affiliation: DNA Replication Laboratory, Rockefeller University, New York, New York, USA.|Howard Hughes Medical Institute, Rockefeller University, New York, New York, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: O'Donnell
mesh_terms: D004261:DNA Replication; D004271:DNA, Fungal / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D009097:Multienzyme Complexes / Q000378:metabolism / Q000648:ultrastructure*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D004271:DNA, Fungal; D009097:Multienzyme Complexes