Related Experiment Video

Updated: Nov 14, 2025

Visualization of DNA Repair Proteins Interaction by Immunofluorescence
07:55

Visualization of DNA Repair Proteins Interaction by Immunofluorescence

Published on: June 26, 2020

10.7K

Mrc1-Dependent Chromatin Compaction Represses DNA Double-Stranded Break Repair by Homologous Recombination Upon

Poyuan Xing1, Yang Dong1, Jingyu Zhao1

  • 1Hubei Key Laboratory of Cell Homeostasis and the Institute for Advanced Studies, College of Life Sciences, Wuhan University, Wuhan, China.

Frontiers in Cell and Developmental Biology
|March 8, 2021
PubMed

Insights

The Mrc1 protein prevents DNA double-strand break repair during replication stress by compacting chromatin, hindering repair protein access. Removing Mrc1 partially restores repair, highlighting its role in genome stability.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • DNA replication and repair coordination is vital for genome stability.
  • The Mrc1-mediated S phase checkpoint inhibits DNA double-strand break (DSB) repair via homologous recombination (HR).
  • The precise mechanism by which the replication checkpoint suppresses HR is not fully understood.

Purpose of the Study:

  • To elucidate how the replication checkpoint inhibits homologous recombination (HR) under replication stress.
  • To investigate the role of Mrc1 in suppressing DNA double-strand break (DSB) repair pathways.
  • To understand the mechanistic link between Mrc1, chromatin structure, and HR suppression.

Main Methods:

  • Investigated the impact of replication stress on DNA resection pathways (Sgs1/Dna2 and Exo1).
  • Assessed the loading of replication protein A (RPA) and Rad51 under replication stress.
  • Utilized deletion mutants of *MRC1* and other factors (Csm3, Tof1, Ctf4) to study HR inhibition.
  • Analyzed chromatin compaction using microscopy and assessed the accessibility of HR proteins.

Main Results:

  • Replication stress suppresses Sgs1/Dna2 and Exo1 resection pathways in an Mrc1-dependent manner.
  • Mrc1-dependent suppression of resection impairs RPA and Rad51 loading, inhibiting DSB repair by HR.
  • Deletion of *MRC1* partially restores resection, RPA/Rad51 loading, and HR.
  • Replication stress induces Mrc1-dependent global chromatin compaction, limiting HR protein access.

Conclusions:

  • Mrc1 plays a critical role in inhibiting DSB end resection and HR under replication stress.
  • Mrc1-dependent chromatin compaction is a key mechanism suppressing HR during replication stress.
  • This study reveals how Mrc1 coordinates DNA replication and recombination through chromatin structure modulation for genome stability.
Keywords:
DNA double-stranded breaksMrc1homologous recombinationreplication checkpointreplication stress

More Related Videos

Author Spotlight: Unraveling the Dynamics of Eukaryotic DNA Replication Through Single-Molecule Visualization07:37

Author Spotlight: Unraveling the Dynamics of Eukaryotic DNA Replication Through Single-Molecule Visualization

Published on: September 27, 2024

2.0K
Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging06:44

Assessment of Global DNA Double-Strand End Resection using BrdU-DNA Labeling coupled with Cell Cycle Discrimination Imaging

Published on: April 28, 2021

4.3K

Related Concept Videos

Homologous Recombination02:31

Homologous Recombination

The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
58.7K
Homologous Recombination02:31

Homologous Recombination

5.5K
The DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication...
38.6K
Fixing Double-strand Breaks02:04

Fixing Double-strand Breaks

The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
13.5K
Fixing Double-strand Breaks02:04

Fixing Double-strand Breaks

3.8K
Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
6.1K