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14:09
Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System
Published on: March 18, 2010
DNA structure-dependent requirements for yeast RAD genes in gene conversion
N Sugawara1, E L Ivanov, J Fishman-Lobell
1Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02254-9110.
Nature
|January 5, 1995
Summary
DNA repair genes RAD51, RAD52, RAD54, RAD55, and RAD57 are crucial for Saccharomyces cerevisiae mating-type switching. RAD52 is essential only when the donor sequence is accessible, highlighting chromatin
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- HO endonuclease-induced mating-type (MAT) switching in Saccharomyces cerevisiae is a mitotic recombination process.
- Donor sequences (HML or HMR) are typically silenced and inaccessible due to chromatin structure.
Purpose of the Study:
- To investigate the role of DNA repair genes in the HO endonuclease-induced MAT switching process.
- To determine how chromatin accessibility of donor sequences affects the requirement for specific DNA repair genes.
Main Methods:
- Utilized physical monitoring of DNA to track recombination events.
- Employed gene deletion strategies for key DNA repair genes (RAD51, RAD52, RAD54, RAD55, RAD57).
- Manipulated donor sequence silencing and chromosomal location (plasmid vs. chromosome).
Main Results:
- MAT switching was blocked at an early recombination step in strains lacking RAD51, RAD52, RAD54, RAD55, or RAD57.
- RAD52 was essential for switching only when the donor sequence was transcribed and on a plasmid.
- RAD51, RAD54, RAD55, and RAD57 remained essential even with a transcribed donor on the chromosome.
Conclusions:
- Recombination in vivo is influenced by the chromatin structure of DNA molecules.
- RAD51, RAD54, RAD55, and RAD57 facilitate strand invasion into inaccessible donor sequences.
- Specific DNA repair pathways are modulated by chromatin accessibility and donor status.
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