Human CST complex protects stalled replication forks by directly blocking MRE11 degradation of nascent-strand DNA
Journal
The EMBO Journal
Journal Volume
40
Journal Issue
2
Pages
e103654
Date Issued
2021
Author(s)
Abstract
Degradation and collapse of stalled replication forks are main sources of genomic instability, yet the molecular mechanisms for protecting forks from degradation/collapse are not well understood. Here, we report that human CST (CTC1-STN1-TEN1) proteins, which form a single-stranded DNA-binding complex, localize at stalled forks and protect stalled forks from degradation by the MRE11 nuclease. CST deficiency increases MRE11 binding to stalled forks, leading to nascent-strand degradation at reversed forks and ssDNA accumulation. In addition, purified CST complex binds to 5’ DNA overhangs and directly blocks MRE11 degradation in vitro, and the DNA-binding ability of CST is required for blocking MRE11-mediated nascent-strand degradation. Our results suggest that CST inhibits MRE11 binding to reversed forks, thus antagonizing excessive nascent-strand degradation. Finally, we uncover that CST complex inactivation exacerbates genome instability in BRCA2 deficient cells. Collectively, our findings identify the CST complex as an important fork protector that preserves genome integrity under replication perturbation. ? 2020 The Authors
Subjects
CST complex; DNA degradation; genome stability; nascent strand; replication stress
Other Subjects
CTC1 STN1 TEN1 complex; double strand break repair protein MRE11; multiprotein complex; Rad51 protein; single stranded DNA; unclassified drug; Ctc1 protein, human; DNA binding protein; DNA helicase; double strand break repair protein MRE11; MRE11 protein, human; protein binding; single stranded DNA; Stn1 protein, human; telomere binding protein; Ten1 protein, human; 5' untranslated region; Article; BRCA2 syndrome cell line; cancer survival; controlled study; correlational study; DNA binding; DNA replication; DNA strand; genetic correlation; genomic instability; HCT 116 cell line; HEK293T cell line; HeLa cell line; human; human cell; in vitro study; priority journal; protein expression level; U2OS cell line; cell line; DNA repair; DNA replication; double stranded DNA break; genetics; HEK293 cell line; metabolism; tumor cell line; Cell Line; Cell Line, Tumor; DNA Breaks, Double-Stranded; DNA Helicases; DNA Repair; DNA Replication; DNA, Single-Stranded; DNA-Binding Proteins; HCT116 Cells; HEK293 Cells; HeLa Cells; Humans; MRE11 Homologue Protein; Protein Binding; Telomere-Binding Proteins
Publisher
EMBO press
Type
journal article