SILAC-based phosphoproteomics reveals new PP2A-Cdc55-regulated processes in budding yeast

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Biology

Background:

• Protein Phosphatase 2A (PP2A) is crucial for cell growth and proliferation.
• The PP2ACdc55 phosphatase is linked to cell cycle events in budding yeast.
• Limited knowledge exists regarding PP2ACdc55 substrates and their functions.

Purpose of the Study:

• To identify novel substrates of PP2ACdc55 phosphatase.
• To uncover new PP2A-related processes during mitosis.
• To investigate PP2ACdc55's role in cell cycle regulation.

Main Methods:

• Quantitative mass spectrometry was employed to identify PP2ACdc55 substrates.
• Phosphoproteomics analysis was performed on Cdc55-deficient cells.
• Protein docking models were constructed to analyze substrate interactions.

Main Results:

• 62 significant PP2ACdc55 substrates were identified, primarily involved in actin-cytoskeleton organization.
• New substrates like Slk19, Lte1, and Zeo1 were validated, implicating PP2ACdc55 in anaphase pathways and cell wall integrity.
• Docking models revealed a key interaction interface on Cdc55 involving residues 84-90.

Conclusions:

• PP2ACdc55 regulates diverse kinases beyond Cdk1, including Pkc1.
• PP2ACdc55 plays a significant role in actin cytoskeleton organization and cytokinesis.
• The study expands understanding of PP2ACdc55 functions in mitosis and cell cycle control.