TopBP1 assembles nuclear condensates to switch on ATR signaling.
Amino Acid Substitution
Animals
Ataxia Telangiectasia Mutated Proteins
/ chemistry
Carrier Proteins
/ chemistry
Cell Nucleus
/ chemistry
Checkpoint Kinase 1
/ chemistry
DNA-Binding Proteins
/ chemistry
HeLa Cells
Humans
Mutation, Missense
Nuclear Proteins
/ chemistry
Sf9 Cells
Signal Transduction
Spodoptera
ATR
DNA damage response
DNA replication
S phase checkpoint
TopBP1
biomolecular condensates
liquid phase separation
optogenetics
proximity-labeling proteomics
signal transduction
Journal
Molecular cell
ISSN: 1097-4164
Titre abrégé: Mol Cell
Pays: United States
ID NLM: 9802571
Informations de publication
Date de publication:
18 03 2021
18 03 2021
Historique:
received:
02
07
2019
revised:
01
10
2020
accepted:
16
12
2020
pubmed:
28
1
2021
medline:
2
4
2021
entrez:
27
1
2021
Statut:
ppublish
Résumé
ATR checkpoint signaling is crucial for cellular responses to DNA replication impediments. Using an optogenetic platform, we show that TopBP1, the main activator of ATR, self-assembles extensively to yield micrometer-sized condensates. These opto-TopBP1 condensates are functional entities organized in tightly packed clusters of spherical nano-particles. TopBP1 condensates are reversible, occasionally fuse, and co-localize with TopBP1 partner proteins. We provide evidence that TopBP1 condensation is a molecular switch that amplifies ATR activity to phosphorylate checkpoint kinase 1 (Chk1) and slow down replication forks. Single amino acid substitutions of key residues in the intrinsically disordered ATR activation domain disrupt TopBP1 condensation and consequently ATR/Chk1 signaling. In physiologic salt concentration and pH, purified TopBP1 undergoes liquid-liquid phase separation in vitro. We propose that the actuation mechanism of ATR signaling is the assembly of TopBP1 condensates driven by highly regulated multivalent and cooperative interactions.
Identifiants
pubmed: 33503405
pii: S1097-2765(20)30991-6
doi: 10.1016/j.molcel.2020.12.049
pii:
doi:
Substances chimiques
Carrier Proteins
0
DNA-Binding Proteins
0
Nuclear Proteins
0
TOPBP1 protein, human
0
ATR protein, human
EC 2.7.11.1
Ataxia Telangiectasia Mutated Proteins
EC 2.7.11.1
CHEK1 protein, human
EC 2.7.11.1
Checkpoint Kinase 1
EC 2.7.11.1
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
1231-1245.e8Commentaires et corrections
Type : CommentIn
Informations de copyright
Copyright © 2021 Elsevier Inc. All rights reserved.
Déclaration de conflit d'intérêts
Declaration of interests The authors declare no competing interests.