An efficient tandem affinity purification procedure for interaction proteomics in mammalian cells

Area of Science:

• Biochemistry
• Molecular Biology
• Proteomics

Background:

• Tandem affinity purification (TAP) isolates protein complexes under physiological conditions for mass spectrometry.
• Conventional TAP yields are often low in mammalian cells, limiting its application.
• Developing efficient protein complex purification methods is crucial for understanding cellular machinery.

Purpose of the Study:

• To design and evaluate novel dual-affinity tags for improved protein complex purification in mammalian cells.
• To compare the efficiency of new tags against the conventional TAP tag.
• To enhance the yield and specificity of protein complex isolation for interaction proteomics.

Main Methods:

• Design and synthesis of several dual-affinity tags optimized for mammalian expression.
• Comparative analysis of tag efficiency using tandem affinity purification.
• Mass spectrometry-based identification and characterization of purified protein complexes.
• Testing the optimized GS-TAP tag using the well-characterized Ku70-Ku80 complex.

Main Results:

• A novel GS-TAP tag, combining protein G and streptavidin-binding peptide, demonstrated a tenfold increase in protein-complex yield.
• The GS-TAP tag significantly improved the specificity of the purification procedure.
• The enhanced method enables purification of previously inaccessible protein complexes.
• Reduced starting material requirements lead to higher success rates in interaction proteomics.

Conclusions:

• The GS-TAP tag represents a significant advancement over conventional TAP for mammalian systems.
• This improved technique facilitates more comprehensive and successful interaction proteomics studies.
• The method allows for the identification of both known and novel components within protein complexes.