Elucidation of novel budding yeast separase mutants

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Mitotic separase, encoded by ESP1, is crucial for cleaving Scc1 in cohesin, enabling sister chromatid separation during anaphase.
• Separase also plays a vital role in DNA damage repair pathways.
• Understanding separase function is key to comprehending cell cycle regulation and genome stability.

Purpose of the Study:

• To isolate and characterize temperature-sensitive (ts) mutants of the budding yeast Saccharomyces cerevisiae ESP1 gene.
• To investigate the role of separase in sister chromatid separation and DNA damage response.
• To identify genetic suppressors and modifiers of separase mutations.

Main Methods:

• Isolation and characterization of 10 temperature-sensitive (ts) mutants of the ESP1 gene.
• Assessing sister chromatid separation defects at restrictive temperatures.
• Evaluating hypersensitivity to genotoxic agents (benomyl, bleomycin).
• Investigating the effects of securin overexpression and identifying high-dosage suppressors (e.g., MPT5).

Main Results:

• All 10 esp1-ts mutants exhibited defects in sister chromatid separation at the restrictive temperature.
• Some mutants showed hypersensitivity to benomyl and/or bleomycin, indicating roles in DNA damage repair.
• Securin overexpression had varied effects, alleviating growth defects in some mutants while exacerbating them in others.
• The Drosophila Pumilio homolog, MPT5, was identified as a high-dosage suppressor.

Conclusions:

• The characterized esp1-ts mutants provide valuable tools for studying separase function in vivo.
• These findings highlight the multifaceted roles of separase in cell division and DNA repair.
• Genetic interactions with securin and MPT5 offer new avenues for exploring separase regulation and function.