Statistical analysis of membrane proteome expression changes in Saccharomyces cerevisiae

Area of Science:

• Proteomics
• Yeast Molecular Biology
• Quantitative Biology

Background:

• Shotgun proteomics generates large datasets requiring robust quantitative analysis.
• Understanding protein expression changes in response to environmental conditions is crucial for cell biology.
• The normalized spectral abundance factor (NSAF) is a metric used for protein quantification.

Purpose of the Study:

• To develop and validate a quantitative proteomics approach using NSAF for analyzing shotgun proteomics data.
• To identify proteins with altered expression levels in Saccharomyces cerevisiae grown under different media conditions.
• To functionally validate changes in specific membrane proteins, such as amino acid transporters.

Main Methods:

• Quantitative proteomics analysis of plasma membrane-enriched samples from S. cerevisiae.
• Utilizing cells grown in 14N-rich and 15N-minimal media.
• Application of normalized spectral abundance factor (NSAF) for protein quantification and statistical analysis (t-test).

Main Results:

• The natural log transformation of NSAF values exhibited a normal distribution.
• A t-test analysis revealed 221 out of 1316 quantified proteins were significantly differentially expressed (p < 0.05) between growth conditions.
• Fourteen membrane proteins, including amino acid transporters, were significantly upregulated in minimal media.

Conclusions:

• The NSAF-based approach provides a reliable method for quantitative proteomics.
• Significant alterations in protein expression occur in S. cerevisiae adapting to nutrient-rich versus minimal media.
• Upregulation of amino acid transporters in minimal media suggests an adaptive response to nutrient scarcity, confirmed by functional assays.