Rad27 and Exo1 function in different excision pathways for mismatch repair in Saccharomyces cerevisiae

Related Experiment Video

Updated: Oct 19, 2025

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae
07:55

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Published on: September 11, 2022

2.0K

Felipe A Calil1, Bin-Zhong Li1, Kendall A Torres1

  • 1Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0660, USA.

Nature Communications
|September 23, 2021
PubMed

Insights

Eukaryotic DNA mismatch repair (MMR) has multiple pathways. This study identifies Rad27 as a key component of an Exo1-independent MMR pathway, revealing pathway redundancy.

Area of Science:

  • Molecular Biology
  • Genetics
  • DNA Repair Mechanisms

Background:

  • Eukaryotic DNA mismatch repair (MMR) utilizes both Exonuclease 1 (Exo1)-dependent and Exo1-independent pathways.
  • The mechanisms of Exo1-independent MMR pathways remain largely uncharacterized.

Purpose of the Study:

  • To investigate the roles of specific mutations in elucidating distinct MMR pathways.
  • To identify novel components and mechanisms within Exo1-independent MMR.

Main Methods:

  • Utilized specific mutations: exo1Δ440-702 (disrupting Exo1 interaction domains), rad27Δ, and pms1-A99V (inactivating an Exo1-independent pathway).
  • Analyzed the effects of combined mutations on MMR functionality.
  • Reconstituted an in vitro MMR reaction using purified proteins and a mispaired DNA substrate.

Main Results:

  • The exo1Δ440-702 mutation, affecting Msh2 and Mlh1 interactions, eliminates Exo1 MMR functions but is viable with rad27Δ.
  • Combinatorial analysis revealed that exo1Δ440-702, rad27Δ, and pms1-A99V each inactivate a distinct MMR pathway.
  • Successfully reconstituted a Rad27- and Msh2-Msh6-dependent MMR reaction in vitro.

Conclusions:

  • Rad27 defines a specific Exo1-independent eukaryotic MMR pathway.
  • This Rad27-dependent pathway is redundant with at least two other MMR pathways.
  • The study clarifies the complex, redundant nature of eukaryotic MMR.

More Related Videos

Laser Micro-Irradiation to Study DNA Recruitment During S Phase07:11

Laser Micro-Irradiation to Study DNA Recruitment During S Phase

Published on: April 16, 2021

4.6K
Author Spotlight: Visualizing Single-Stranded DNA During DNA Repair for Therapeutic Insights08:30

Author Spotlight: Visualizing Single-Stranded DNA During DNA Repair for Therapeutic Insights

Published on: December 22, 2023

2.9K

Related Concept Videos

Base Excision Repair01:54

Base Excision Repair

One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing and strand breakage during replication. This type of damage causes minimal change to the DNA double helix structure and can be repaired by the base excision repair (BER) pathways. BER corrects damaged DNA sequences by removing the damaged base and restoring the original base sequence using the complementary strand as a template.
The first step of...
23.8K
Nucleotide Excision Repair01:38

Nucleotide Excision Repair

DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
4.1K
Mismatch Repair01:20

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
5.4K
Long-patch Base Excision Repair01:02

Long-patch Base Excision Repair

Since the discovery of the two BER pathways, there has been a debate about how a cell chooses one pathway over the other and the factors determining this selection. Numerous in vitro experiments have pointed out multiple determinants for the sub-pathway selection. These are:
7.3K
Conservative Site-specific Recombination and Phase Variation02:53

Conservative Site-specific Recombination and Phase Variation

Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
6.2K
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...
55.8K