Physical and functional interactions between polo kinase and the spindle pole component Cut12 regulate mitotic...

Area of Science:

• Cell cycle regulation
• Molecular biology
• Yeast genetics

Background:

• Mitotic commitment is controlled by Maturation-Promoting Factor (MPF), regulated by Wee1 kinases and Cdc25 phosphatase.
• Feedback loops involving polo kinase (Plo1) likely contribute to MPF activation.
• Mutations in Cut12, a spindle pole body component in Schizosaccharomyces pombe, affect mitotic commitment.

Purpose of the Study:

• To investigate the interaction between Cut12 and Plo1 in Schizosaccharomyces pombe.
• To elucidate the role of Cut12 in regulating Plo1 activity and its impact on mitotic commitment.

Main Methods:

• Yeast two-hybrid assays and immunoprecipitation to assess Cut12-Plo1 interaction.
• In vivo MPM-2 staining and in vitro kinase assays to evaluate Plo1 activity.
• Genetic analysis using loss-of-function and gain-of-function mutations in Cut12 and Plo1.

Main Results:

• Cut12 physically associates with Plo1.
• Plo1 activity is required for proper spindle pole body (SPB) recognition during mitosis.
• The gain-of-function cut12.s11 mutation enhances Plo1 activity, suppressing mitotic commitment defects.
• Compromised Plo1 function negates the suppressive effect of cut12.s11.
• Constitutively active Plo1 rescues the mitotic commitment defect in cdc25.22 cells.

Conclusions:

• Cut12 regulates mitotic commitment by modulating Plo1 activity.
• Plo1 is a key component in the regulatory network controlling MPF activation in Schizosaccharomyces pombe.
• The cut12.s11 mutation suppresses cdc25.22 defects through enhanced Plo1 activity.