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Supercomplex formation between Mlh1-Mlh3 and Sgs1-Top3 heterocomplexes in meiotic yeast cells
1Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan, ROC. tfwang@gate.sinica.edu.tw
Abstract:
The genome of Saccharomyces cerevisia encodes four mismatch repair MutL proteins and these proteins form three heterocomplexes: Mlh1-Mlh2, Mlh1-Mlh3, and Mlh1-Pms1. Only, the Mlh1-Mlh3 heterocomplex has been implicated specifically in promotion of meiotic crossing-over. In this report, we show that yeast Mlh3 co-immunoprecipitates with Sgs1 helicase in sporulating cells at late stage of meiotic prophase I. Sgs1, a member of the RecQ DNA helicase family, appears to form a stable complex with topoisomerase III (Top3) during meiosis. We suggest that Mlh1-Mlh3 heterocomplex may act as a molecular matchmaker to coordinate Sgs1-Top3 complex in the resolution of meiotic recombination intermediates.
Insights
The Mlh1-Mlh3 complex in yeast interacts with the Sgs1-Top3 complex during meiosis. This interaction is crucial for resolving meiotic recombination intermediates and promoting crossing-over.
Area of Science:
- Molecular biology
- Genetics
- Cell biology
Background:
- Saccharomyces cerevisiae possesses four MutL proteins forming three heterocomplexes: Mlh1-Mlh2, Mlh1-Mlh3, and Mlh1-Pms1.
- The Mlh1-Mlh3 heterocomplex is specifically linked to promoting meiotic crossing-over.
Purpose of the Study:
- To investigate the role of the Mlh1-Mlh3 heterocomplex in meiotic recombination.
- To explore potential interactions between Mlh1-Mlh3 and other key meiotic proteins.
Main Methods:
- Co-immunoprecipitation assays were used to detect protein interactions.
- Analysis was performed on sporulating yeast cells during late meiotic prophase I.
Main Results:
- Yeast Mlh3 was shown to co-immunoprecipitate with the Sgs1 helicase.
- The Sgs1 helicase, a RecQ DNA helicase family member, forms a stable complex with topoisomerase III (Top3) during meiosis.
Conclusions:
- The Mlh1-Mlh3 heterocomplex may function as a molecular scaffold.
- This scaffold likely coordinates the Sgs1-Top3 complex in resolving meiotic recombination intermediates, thereby facilitating meiotic crossing-over.