6Z3A

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

Summary for 6Z3A

• Entry DOI: 10.2210/pdb6z3a/pdb
• EMDB information: 11050 11055
• Descriptor: Serine/threonine-protein kinase MEC1, DNA damage checkpoint protein LCD1, PHOSPHOAMINOPHOSPHONIC ACID-ADENYLATE ESTER, ... (4 entities in total)
• Functional Keywords: serine/threonine protein kinase, complex, dna damage response, checkpoint control, hydrolase
• Biological source: Saccharomyces cerevisiae S288C; More
• Total number of polymer chains: 4
• Total formula weight: 721572.02

Authors

Yates, L.A.,Zhang, X. (deposition date: 2020-05-19, release date: 2020-11-11, Last modification date: 2024-05-22)

Primary citation

Tannous, E.A.,Yates, L.A.,Zhang, X.,Burgers, P.M.
Mechanism of auto-inhibition and activation of Mec1 ATR checkpoint kinase.
Nat.Struct.Mol.Biol., 28:50-61, 2021

PubMed Abstract: In response to DNA damage or replication fork stalling, the basal activity of Mec1 is stimulated in a cell-cycle-dependent manner, leading to cell-cycle arrest and the promotion of DNA repair. Mec1 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 Mg-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.

PubMed: 33169019
DOI: 10.1038/s41594-020-00522-0

Experimental method

ELECTRON MICROSCOPY (3.8 Å)