Simple, scalable, and ultrasensitive tip-based identification of protease substrates

Area of Science:

• Biochemistry
• Proteomics
• Molecular Biology

Background:

• Proteases and their substrates are crucial drug targets in numerous diseases.
• Mass spectrometry, using methods like COFRADIC and TAILS, is key for discovering protease substrates via N-terminal peptide enrichment.
• Existing methods require optimization for sensitivity and simplicity in identifying protease targets.

Purpose of the Study:

• To present Charge-Based Fractional Diagonal Chromatography (ChaFRADIC) as a novel, simplified protocol for N-terminal peptide enrichment.
• To demonstrate the high sensitivity and efficiency of ChaFRADIC for identifying protease substrates and consensus motifs.
• To apply ChaFRADIC to investigate dynamic changes during staurosporine-induced apoptosis.

Main Methods:

• Development of the Charge-Based Fractional Diagonal Chromatography (ChaFRADIC) protocol for N-terminal peptide enrichment.
• Quantification of unique N-terminal peptides using iTRAQ-8-plex, analyzing samples from 4.3 μg per channel.
• Application of the method to study apoptosis dynamics induced by staurosporine at different time points (1.5h, 3h, 6h).

Main Results:

• ChaFRADIC enabled the identification of an average of 2,073 unique N-terminal peptides per sample.
• The method demonstrated high sensitivity, potentially enabling analysis of clinical samples like needle biopsies.
• Data revealed orchestrated pathway regulation during staurosporine-induced apoptosis, with early targeting of homeostasis players and modulation of splicing machinery.

Conclusions:

• ChaFRADIC is a simple, sensitive, and effective method for N-terminal peptide enrichment and protease substrate discovery.
• The study identified early molecular events in staurosporine-induced apoptosis, highlighting the role of proteolysis and phosphorylation in modulating the splicing machinery.
• This approach holds promise for future applications in clinical diagnostics and disease research.