ETD-Based Proteomic Profiling Improves Arginine Methylation Identification and Reveals Novel PRMT5 Substrates

Area of Science:

• Biochemistry
• Proteomics
• Cell Biology

Background:

• Protein arginine methylation is a crucial post-translational modification (PTM) in eukaryotes.
• Conventional mass spectrometry methods struggle to identify methylarginine sites due to neutral losses.

Purpose of the Study:

• To develop an optimized mass spectrometry workflow for deep profiling of arginine methylation.
• To improve the identification and site localization of symmetric dimethylarginine (sDMA).

Main Methods:

• Developed an optimized mass spectrometry workflow using electron-transfer dissociation (ETD) with supplemental activation.
• Applied quantitative proteomics to identify sDMA sites in human HeLa cells.
• Conducted biochemical studies on identified substrates like SERBP1.

Main Results:

• The ETD-based workflow significantly enhanced sDMA identification and site localization.
• Identified 138 novel sDMA sites, suggesting potential PRMT5 substrates.
• Demonstrated that SERBP1 methylation is crucial for its recruitment to stress granules under oxidative stress.

Conclusions:

• The optimized workflow enables extensive identification and localization of sDMA sites in human cells.
• Discovered novel PRMT5 substrates with potentially significant biological functions related to sDMA.
• Highlight the importance of arginine methylation in regulating protein localization during cellular stress.