Esc4/Rtt107 and the control of recombination during replication.
When replication forks stall during DNA synthesis, cells respond by assembling multi-protein complexes to control the various pathways that stabilize the replication machinery, repair the replication fork, and facilitate the reinitiation of processive DNA synthesis. Increasing evidence suggests that cells have evolved scaffolding proteins to orchestrate and control the assembly of these repair complexes, typified in mammalian cells by several BRCT-motif containing proteins, such as Brca1, Xrcc1, and 53BP1. In Saccharomyces cerevisiae, Esc4 contains six such BRCT domains and is required for the most efficient response to a variety of agents that damage DNA. We show that Esc4 interacts with several proteins involved in the repair and processing of stalled or collapsed replication forks, including the recombination protein Rad55. However, the function of Esc4 does not appear to be restricted to a Rad55-dependent process, as we observed an increase in sensitivity to the DNA alkylating agent methane methylsulfonate (MMS) in a esc4Deltarad55Delta mutant, as well as in double mutants of esc4Delta and other recombination genes, compared to the corresponding single mutants. In addition, we show that Esc4 forms multiple nuclear foci in response to treatment with MMS. Similar behavior is also observed in the absence of damage when either of the S-phase checkpoint proteins, Tof1 or Mrc1, is deleted. Thus, we propose that Esc4 associates with ssDNA of stalled forks and acts as a scaffolding protein to recruit and/or modulate the function of other proteins required to reinitiate DNA synthesis.
Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA.
Jodie K
JK
Chin
Vladimir I
VI
Bashkirov
Wolf-Dietrich
WD
Heyer
Floyd E
FE
Romesberg
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D064447:Checkpoint Kinase 2; D004260:DNA Repair; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008954:Models, Biological; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C087191:RAD55 protein, S cerevisiae; C501265:RTT107 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D064447:Checkpoint Kinase 2; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae