6z2w
From Proteopedia
Mec1-Ddc2 (F2244L mutant) in complex with Mg AMP-PNP
Structural highlights
FunctionLCD1_YEAST Forms a complex with the serine/threonine kinase MEC1 which activates checkpoint signaling upon genotoxic stresses. The MEC1-LCD1 complex is recruited by the single-strand-binding protein complex RPA to DNA lesions in order to initiate the DNA repair by homologous recombination, after the MRX-complex and TEL1 are displaced. Required for the recruitment of MEC1 to DNA lesions, the activation of CHK1 and RAD53 kinases and phosphorylation of RAD9 in response to DNA damage. Required for cell growth and meiotic recombination.[1] [2] [3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedIn response to DNA damage or replication fork stalling, the basal activity of Mec1(ATR) is stimulated in a cell-cycle-dependent manner, leading to cell-cycle arrest and the promotion of DNA repair. Mec1(ATR) dysfunction leads to cell death in yeast and causes chromosome instability and embryonic lethality in mammals. Thus, ATR is a major target for cancer therapies in homologous recombination-deficient cancers. Here we identify a single mutation in Mec1, conserved in ATR, that results in constitutive activity. Using cryo-electron microscopy, we determine the structures of this constitutively active form (Mec1(F2244L)-Ddc2) at 2.8 A and the wild type at 3.8 A, both in complex with Mg(2+)-AMP-PNP. These structures yield a near-complete atomic model for Mec1-Ddc2 and uncover the molecular basis for low basal activity and the conformational changes required for activation. Combined with biochemical and genetic data, we discover key regulatory regions and propose a Mec1 activation mechanism. Mechanism of auto-inhibition and activation of Mec1(ATR) checkpoint kinase.,Tannous EA, Yates LA, Zhang X, Burgers PM Nat Struct Mol Biol. 2021 Jan;28(1):50-61. doi: 10.1038/s41594-020-00522-0. Epub , 2020 Nov 9. PMID:33169019[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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