DNA Mismatch Repair Mechanisms and Applications

DNA mismatch repair (MMR) is a conserved pathway that preserves genome integrity by recognising and correcting base–base mismatches and insertion–deletion loops arising during replication and recombination. The process is initiated by MutS homologues that detect helical distortions and recruit MutL homologues to form a sliding clamp on DNA. Strand discrimination relies on transient signals such as nicks or epigenetic marks to direct excision by exonucleases, followed by DNA synthesis and ligation. Beyond its canonical role in replication fidelity, MMR influences double‐strand break repair pathway choice, chromatin stability and mutational signatures in cancer. Defects in human MMR genes underlie hereditary colorectal and endometrial cancers, as well as sporadic tumours exhibiting microsatellite instability. Recent advances have characterised non‐canonical pathways in prokaryotes and revealed cell‐to‐cell variation in repair efficiency, with implications for microbial evolution and antibiotic resistance. In clinical settings, MMR status informs diagnosis, prognosis and therapeutic strategies, including the use of immune checkpoint inhibitors. Furthermore, engineered modulation of MMR components is emerging in biotechnology, for example to control mutation rates in synthetic biology and directed evolution.

Research from Nature Portfolio

Real‐time cellular analyses have visualised the fate of individual replication errors in bacterial cells by combining fluorescently labelled MMR complexes with microfluidics and time‐lapse microscopy. This work reveals that many mismatches are detected yet inefficiently excised due to a fleeting strand discrimination signal and that repair capacity varies between isogenic cells, generating subpopulations with elevated mutation rates. Such heterogeneity may accelerate adaptation, including antibiotic resistance.
Independent studies have identified an alternative MMR pathway in bacteria lacking canonical MutS–MutL proteins. A novel endonuclease, NucS/EndoMS, fulfils MutS‐like functions in recognition and correction, enforcing anti‐recombination and mutation avoidance. Phylogenetic analysis suggests that distinct MMR systems have evolved convergently, highlighting the versatility of genomic maintenance strategies.

DNA Mismatch Repair Mechanisms and Applications publication trend

The graph below shows the total number of articles in dna mismatch repair mechanisms and applications across all publications each year (not limited to Nature Index journals).

Technical terms

MutS homologues: Proteins that recognise and bind to mismatched base pairs in DNA.

MutL homologues: ATP-binding proteins that interact with MutS–DNA complexes to coordinate excision.

Strand discrimination signal: A molecular mark, such as a nick or methylation, that distinguishes the newly synthesised DNA strand.

Sliding clamp: A ring-shaped complex that encircles DNA, allowing repair proteins to diffuse along the helix.

Exonuclease 1 (EXO1): A 5′→3′ nuclease that removes a tract of DNA containing the mismatch.

Polymerase θ-mediated end-joining: An alternative, error-prone double-strand break repair pathway utilising polymerase θ.

References

1. Real-time monitoring of replication errors’ fate reveals the origin and dynamics of spontaneous mutations. Nature Communications (2024).
2. A non-canonical mismatch repair pathway in prokaryotes. Nature Communications (2017).
3. MSH2-MSH3 promotes DNA end resection during homologous recombination and blocks polymerase theta-mediated end-joining through interaction with SMARCAD1 and EXO1. Nucleic Acids Research (2023).
4. MRE11A: a novel negative regulator of human DNA mismatch repair. Cellular & Molecular Biology Letters (2024).
5. Action-At-A-Distance in DNA Mismatch Repair: Mechanistic Insights and Models for How DNA and Repair Proteins Facilitate Long-Range Communication. Biomolecules (2024).
6. MutS/MutL crystal structure reveals that the MutS sliding clamp loads MutL onto DNA. eLife (2015).