A key role for Ctf4 in coupling the MCM2-7 helicase to DNA polymerase alpha within the eukaryotic replisome.
The eukaryotic replisome is a crucial determinant of genome stability, but its structure is still poorly understood. We found previously that many regulatory proteins assemble around the MCM2-7 helicase at yeast replication forks to form the replisome progression complex (RPC), which might link MCM2-7 to other replisome components. Here, we show that the RPC associates with DNA polymerase alpha that primes each Okazaki fragment during lagging strand synthesis. Our data indicate that a complex of the GINS and Ctf4 components of the RPC is crucial to couple MCM2-7 to DNA polymerase alpha. Others have found recently that the Mrc1 subunit of RPCs binds DNA polymerase epsilon, which synthesises the leading strand at DNA replication forks. We show that cells lacking both Ctf4 and Mrc1 experience chronic activation of the DNA damage checkpoint during chromosome replication and do not complete the cell cycle. These findings indicate that coupling MCM2-7 to replicative polymerases is an important feature of the regulation of chromosome replication in eukaryotes, and highlight a key role for Ctf4 in this process.
Gambus
Agnieszka
A
Cancer Research UK, Paterson Institute for Cancer Research, University of Manchester, Manchester, UK.
van Deursen
Frederick
F
Polychronopoulos
Dimitrios
D
Foltman
Magdalena
M
Jones
Richard C
RC
Edmondson
Ricky D
RD
Calzada
Arturo
A
Labib
Karim
K
D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D004247:DNA / Q000378:metabolism; D004256:DNA Polymerase I / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D064168:Minichromosome Maintenance Complex Component 7; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
C078338:CTF4 protein, S cerevisiae; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C441579:MRC1 protein, S cerevisiae; D009687:Nuclear Proteins; C022262:Okazaki fragments; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D004256:DNA Polymerase I; C083536:POL1 protein, S cerevisiae; C069199:MCM2 protein, S cerevisiae; C491088:MCM7 protein, S cerevisiae; D064168:Minichromosome Maintenance Complex Component 7