title: Function of Rad17/Mec3/Ddc1 and its partial complexes in the DNA damage checkpoint.
abstract: The Saccharomyces cerevisiae heterotrimeric checkpoint clamp consisting of the Rad17, Mec3, and Ddc1 subunits (Rad17/3/1, the 9-1-1 complex in humans) is an early response factor to DNA damage in a signal transduction pathway leading to the activation of the checkpoint system and eventually to cell cycle arrest. These subunits show structural similarities with the replication clamp PCNA and indeed, it was demonstrated in vitro that Rad17/3/1 could be loaded onto DNA by checkpoint specific clamp loader Rad24-RFC, analogous to the PCNA-RFC clamp-clamp loader system. We have studied the interactions between the checkpoint clamp subunits and the activity of partial clamp complexes. We find that none of the possible partial complexes makes up a clamp that can be loaded onto DNA by Rad24-RFC. In agreement, overexpression of DDC1 or RAD17 in a MEC3Delta strain, or of MEC3 or RAD17 in a DDC1Delta strain shows no rescue of damage sensitivity.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Majka
authors.forename: Peter M
authors.initials: PM
authors.lastname: Burgers
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C440013:Ddc1 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; C099938:MEC3 protein, S cerevisiae; D009687:Nuclear Proteins; D010750:Phosphoproteins; C501395:RAD17 protein, S cerevisiae; C088385:RAD24 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA