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Visualization of eukaryotic DNA mismatch repair reveals distinct recognition and repair intermediates

Hans Hombauer1, Christopher S Campbell, Catherine E Smith

  • 1Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA.

Cell
|November 29, 2011
PubMed

Insights

DNA mismatch repair (MMR) uses Msh2-Msh6 and Mlh1-Pms1 complexes to fix replication errors. Visualizing these proteins revealed distinct roles and pathways in DNA repair, enhancing our understanding of replication fidelity.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • DNA mismatch repair (MMR) is crucial for maintaining genomic stability by correcting replication errors.
  • In yeast, the Msh2-Msh6 complex detects mispairs, and the Mlh1-Pms1 complex facilitates correction.

Purpose of the Study:

  • To visualize the dynamic behavior of Msh2-Msh6 and Mlh1-Pms1 complexes in living yeast cells.
  • To elucidate the distinct roles and localization patterns of MMR proteins during DNA repair.

Main Methods:

  • Utilized functional fluorescently tagged Msh2-Msh6 and Mlh1-Pms1 proteins.
  • Observed protein localization and dynamics in living Saccharomyces cerevisiae cells using microscopy.
  • Manipulated the number of mispaired bases to assess MMR complex responses.

Main Results:

  • Msh2-Msh6 localizes to replication centers during S phase, independent of mispaired bases, contributing to MMR.
  • Mlh1-Pms1 forms nuclear foci dependent on Msh2-Msh6 but rarely colocalizes with it.
  • Mlh1-Pms1 foci formation is stimulated by increased mispaired bases, unlike Msh2-Msh6 foci.

Conclusions:

  • Msh2-Msh6 participates in both replication-coupled and independent pathways for mispair recognition.
  • Distinct pathways involving Msh2-Msh6 lead to the formation of Mlh1-Pms1 foci at active MMR sites.

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