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Mismatch Repair

Mismatch Repair

Mismatch Repair

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...

Translesion DNA Polymerases

Translesion DNA Polymerases

Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...

Proofreading

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template DNA strand. DNA polymerase has a higher affinity to add the correct base and ensures fidelity during DNA replication. Furthermore, it exhibits proofreading activity during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.
Errors During Replication are Corrected by the DNA Polymerase Enzyme

Proofreading

Proofreading

Synthesis of new DNA molecules starts when DNA polymerase links nucleotides together in a sequence that is complementary to the template DNA strand. DNA polymerase has a higher affinity for the correct base to ensure fidelity in DNA replication. The DNA polymerase furthermore proofreads during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.Errors during Replication Are Corrected by the DNA Polymerase EnzymeGenomic DNA is synthesized in...

Spontaneous and Induced Mutations

Spontaneous and Induced Mutations

Spontaneous mutations arise infrequently during DNA replication due to errors in the process. A key factor behind these errors is tautomeric shifts in nitrogenous bases, where bases transition from keto to enol forms or amino to imino forms. This shift can alter base-pairing rules, leading to mutations. Additionally, reactive oxygen species (ROS) arising from aerobic metabolism can damage DNA, resulting in depurination (loss of a purine base) or depyrimidination (loss of a pyrimidine base).

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Related Experiment Video

Updated: Jun 20, 2026

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Following the Dynamics of Structural Variants in Experimentally Evolved Populations

Published on: February 3, 2023

A novel interaction between human DNA polymerase eta and MutLalpha.

Rie Kanao¹, Fumio Hanaoka, Chikahide Masutani

¹Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan.

Biochemical and Biophysical Research Communications

|August 26, 2009

Summary

Human DNA polymerase eta (Poleta) interacts with mismatch repair (MMR) proteins, including MLH1. This interaction, crucial for DNA repair, is more prominent during DNA replication, suggesting a role in maintaining genomic stability.

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Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein

Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein

Published on: March 31, 2010

Area of Science:

Molecular Biology
Genetics
DNA Repair Mechanisms

Background:

DNA polymerase eta (Poleta) is critical for translesion DNA synthesis and is linked to xeroderma pigmentosum variant.
Mismatch repair (MMR) proteins, such as MLH1, are essential for correcting DNA replication errors.

Purpose of the Study:

To identify proteins that interact with human DNA polymerase eta (Poleta).
To investigate the functional significance of Poleta's interaction with MMR proteins, particularly MLH1.

Main Methods:

Co-immunoprecipitation assays were used to detect protein-protein interactions.
Analysis of protein complexes formed with Poleta, including interactions with MLH1/PMS2 (MutLalpha) and MSH2/MSH6 (MutSalpha).
Examination of protein abundance in chromatin-bound complexes during different cell cycle phases.

Main Results:

Human MLH1, a key MMR protein, was identified as a Poleta-interacting protein.
Poleta interacts with the MLH1/PMS2 heterodimer (MutLalpha) and the MSH2/MSH6 heterodimer (MutSalpha).
The interaction between Poleta and MMR proteins is more pronounced in S phase-synchronized cells, indicating a role during DNA replication.

Conclusions:

Poleta physically interacts with essential MMR proteins MutLalpha and MutSalpha.
The interaction between Poleta and MLH1 is likely involved in DNA replication and maintaining genomic integrity.
These findings reveal a novel connection between translesion synthesis and DNA mismatch repair pathways.