A Genetic Toggle for Chemical Control of Individual Plk1 Substrates

Area of Science:

• Cell Biology
• Biochemistry
• Molecular Genetics

Background:

• Polo-like kinase 1 (Plk1) is crucial for regulating mitosis, with numerous substrates and functions.
• Controlling specific Plk1 substrates is challenging due to its complex roles during the cell cycle.

Purpose of the Study:

• To develop a chemical-genetic system for precise control over Plk1 substrate phosphorylation.
• To investigate the functional consequences of toggling specific phosphorylation sites on Plk1 substrates.

Main Methods:

• Engineered Plk1 variants (Plk1^S and Plk1^T) with altered phosphoacceptor selectivity.
• Biochemical assays and phosphoproteomic analysis of mitotic cell extracts.
• Utilized a genetic Ser/Thr toggle system to control Kif2b phosphorylation.

Main Results:

• Plk1^S and Plk1^T selectively phosphorylate Ser and Thr residues, respectively.
• Plk1^S sustains mitotic progression, while Plk1^T does not, allowing for chemical control.
• Toggling Kif2b phosphorylation from Ser to Thr resulted in chromosome misalignment and prometaphase arrest.

Conclusions:

• Demonstrated a novel method for chemically controlling individual Plk1 substrates via a Ser/Thr toggle.
• This system provides a powerful tool for dissecting Plk1 function and substrate roles in mitosis.
• Highlights the importance of specific phosphorylation events in regulating chromosome alignment.