Mrc1 and Tof1 regulate DNA replication forks in different ways during normal S phase.
The Mrc1 and Tof1 proteins are conserved throughout evolution, and in budding yeast they are known to associate with the MCM helicase and regulate the progression of DNA replication forks. Previous work has shown that Mrc1 is important for the activation of checkpoint kinases in responses to defects in S phase, but both Mrc1 and Tof1 also regulate the normal process of chromosome replication. Here, we show that these two important factors control the normal progression of DNA replication forks in distinct ways. The rate of progression of DNA replication forks is greatly reduced in the absence of Mrc1 but much less affected by loss of Tof1. In contrast, Tof1 is critical for DNA replication forks to pause at diverse chromosomal sites where nonnucleosomal proteins bind very tightly to DNA, and this role is not shared with Mrc1.
Hodgson
Ben
B
Cancer Research U.K., Paterson Institute for Cancer Research, University of Manchester, Manchester M20 4BX, United Kingdom.
Calzada
Arturo
A
Labib
Karim
K
D018797:Cell Cycle Proteins / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism; D015825:Chromosomes, Fungal / Q000378:metabolism; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; C441579:MRC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C119636:TOF1 protein, S cerevisiae