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Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System
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Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System

Published on: March 18, 2010

Mms22p protects Saccharomyces cerevisiae from DNA damage induced by topoisomerase II

E L Baldwin1, A C Berger, A H Corbett

  • 1Department of Biochemistry, Vanderbilt University School of Medicine Nashville, TN 37232-0146, USA.

Nucleic Acids Research
|February 19, 2005
PubMed

Insights

DNA repair pathways are crucial for cancer treatment. This study identifies the single-strand invasion pathway and Mms22p as key players in repairing topoisomerase II-induced DNA damage in yeast.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • Topoisomerase II (TOP2) cleavage creates DNA breaks, vital for cancer therapy but also linked to cancer initiation.
  • Understanding the repair mechanisms for TOP2-induced DNA damage is critical for developing effective cancer treatments.

Purpose of the Study:

  • To identify genes and pathways involved in repairing topoisomerase II-mediated DNA damage using a genome-wide approach in Saccharomyces cerevisiae.
  • To elucidate the specific role of Mms22p in DNA damage response and cell cycle regulation.

Main Methods:

  • Genome-wide screening of etoposide-hypersensitive yeast strains.
  • Analysis of homologous recombination pathways, including the single-strand invasion pathway.
  • Cell cycle analysis of wild-type and mutant strains.
  • Epistasis analysis of MMS22 with RTT101 and RTT107.
  • Localization studies of Mms22p.

Main Results:

  • Several genes, including MRE11, XRS2, RAD50, RAD51, RAD52, RAD54, RAD55, RAD57, and MMS22, are essential for etoposide resistance.
  • The single-strand invasion pathway of homologous recombination is confirmed as the primary repair mechanism for TOP2-induced DNA damage.
  • Mms22p plays a significant role in DNA repair, functioning independently of the canonical single-strand invasion pathway, and its absence leads to G2/M cell cycle arrest.
  • Mms22p interacts with RTT101 and RTT107 and localizes to nuclear foci, suggesting a role in DNA processing.

Conclusions:

  • Homologous recombination, particularly the single-strand invasion pathway, is the major repair mechanism for topoisomerase II-induced DNA damage in yeast.
  • Mms22p is a novel factor involved in DNA repair and cell cycle control, with a role distinct from the core homologous recombination machinery.
  • Further investigation into Mms22p function could reveal new therapeutic targets for cancer treatment.

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