title: A tale of two tails: activation of DNA damage checkpoint kinase Mec1/ATR by the 9-1-1 clamp and by Dpb11/TopBP1.
abstract: The DNA damage and replication checkpoint kinase Mec1/ATR is a member of the PI3-kinase related kinases that function in response to various genotoxic stresses. The checkpoint clamp 9-1-1 (Rad9-Rad1-Hus1 in S. pombe and mammals; Ddc1-Rad17-Mec3 in S. cerevisiae) executes two distinct checkpoint functions. In S. cerevisiae, DNA-bound 9-1-1 directly activates Mec1 kinase activity, a function that has not been demonstrated in other organisms. A second, conserved activity of 9-1-1 is that of TopBP1/Cut5/Dpb11 recruitment to stalled replication sites; subsequent activation of Mec1/ATR is carried out by TopBP1/Cut5/Dpb11. Biochemical studies indicate that the mode of Mec1/ATR activation by S. cerevisiae 9-1-1 is analogous to activation by S. cerevisiae Dpb11 or by vertebrate TopBP1: activation is mediated by the intrinsically disordered C-terminal tail of each activator. The relative contributions made by multiple activators of Mec1/ATR are discussed.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, United States.
authors.forename: Vasundhara M
authors.initials: VM
authors.lastname: Navadgi-Patil
authors.forename: Peter M
authors.initials: PM
authors.lastname: Burgers
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D004249:DNA Damage; D004789:Enzyme Activation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C097185:DPB11 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases