Multiple approaches to study S. cerevisiae Rad9, a prototypical checkpoint protein

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• The Saccharomyces cerevisiae RAD9 gene is a key component of the DNA damage response.
• Rad9 is essential for checkpoint control during late G1, S phase, and the G2/M transition after DNA damage.
• Rad9 plays roles in lesion recognition, DNA repair, and maintaining genome stability, and is required for Rad53 activation.

Purpose of the Study:

• To describe methodologies for studying G1, intra-S, and G2/M checkpoints in budding yeast.
• To detail the analysis of Rad9 and Rad53 protein modifications and functions.
• To present techniques for investigating Rad9's cellular localization and interactions.

Main Methods:

• Established protocols for analyzing G1, intra-S, and G2/M cell cycle checkpoints.
• Methods for analyzing Rad9/Rad53 phosphorylation.
• Biochemical assays for Rad9 and Rad53.
• Chromatin fractionation to isolate soluble and chromatin-associated proteins.
• Live-cell imaging of Green Fluorescent Protein (GFP)-tagged Rad9.

Main Results:

• Developed and validated comprehensive methodologies for studying budding yeast DNA damage checkpoints.
• Characterized Rad9 and Rad53 protein states and biochemical activities.
• Demonstrated the fractionation of Rad9 between soluble and chromatin-associated fractions.
• Visualized the dynamic localization of Rad9 within live cells.

Conclusions:

• The described methodologies provide a robust framework for investigating DNA damage checkpoint mechanisms.
• These methods facilitate a deeper understanding of Rad9's roles in cell cycle regulation and genome integrity.
• The study offers tools for future research into DNA repair and checkpoint control in Saccharomyces cerevisiae.