EMD-11055

Single-particle
3.8 Å
EMD-11055 Deposition: 19/05/2020
Map released: 11/11/2020
Last modified: 22/05/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-11055

Mec1-Ddc2 (wild-type) in complex with AMP-PNP

EMD-11055

Single-particle
3.8 Å
EMD-11055 Deposition: 19/05/2020
Map released: 11/11/2020
Last modified: 22/05/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Saccharomyces cerevisiae S288C
Sample: Mec1-Ddc2
Fitted models: 6z3a (Avg. Q-score: 0.257)

Deposition Authors: Yates LA , Zhang X
Mechanism of auto-inhibition and activation of Mec1 ATR checkpoint kinase.
Tannous EA , Yates LA , Zhang X , Burgers PM
(2021) Nat Struct Mol Biol , 28 , 50 - 61
PUBMED: 33169019
DOI: doi:10.1038/s41594-020-00522-0
ISSN: 1545-9985
Abstract:
In response to DNA damage or replication fork stalling, the basal activity of Mec1ATR is stimulated in a cell-cycle-dependent manner, leading to cell-cycle arrest and the promotion of DNA repair. Mec1ATR 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 Å and the wild type at 3.8 Å, both in complex with Mg2+-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.