Systematic control of protein interaction using a modular ER/K α-helix linker

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Protein interactions are crucial for cellular functions.
• Interaction frequency depends on local concentration and affinity.
• Existing methods lack systematic control over intramolecular interaction concentrations.

Purpose of the Study:

• To introduce a modular, genetically encoded ER/K alpha-helix linker.
• To regulate the frequency of protein-protein or protein-peptide interactions.
• To systematically vary effective concentrations in intramolecular interactions.

Main Methods:

• Utilized an ER/K (glutamic acid/arginine or lysine) alpha-helix as a genetically encoded linker.
• Employed calmodulin and its binding peptides with a range of affinities.
• Applied Förster Resonance Energy Transfer (FRET) to quantify interaction dynamics.

Main Results:

• Increasing ER/K alpha-helix length reduced the on-rate of intramolecular interactions.
• The off-rate remained largely unaffected by linker length.
• Demonstrated a genetically encoded method to determine dissociation constants (Kd) for various affinities.

Conclusions:

• The ER/K alpha-helix provides a tool to systematically engineer FRET biosensors.
• This linker can modulate enzyme autoinhibition by controlling protein interactions.
• Findings support a worm-like chain model for the ER/K helix, explaining myosin VI's actin-based movement.