Systems-level effects of allosteric perturbations to a model molecular switch.

Area of Science:

• Molecular biology
• Biochemistry
• Cellular signaling

Background:

• Molecular switch proteins are crucial for signal transduction and operate within complex interaction networks.
• Understanding functional specificity is key when common regulators are shared across different biological processes.

Purpose of the Study:

• To investigate how functional specificity is achieved in the small GTPase switch protein Gsp1 (RAN) in Saccharomyces cerevisiae.
• To determine the relationship between Gsp1 (RAN) interaction interface perturbations and cellular effects.

Main Methods:

• Generated 55 targeted point mutations in Gsp1 (RAN) protein interaction interfaces.
• Utilized quantitative genetic and physical interaction mapping to assess cellular consequences.
• Analyzed the biophysical effects of mutations on GTPase switch cycle kinetics.

Main Results:

• Gsp1 (RAN) interface mutations had widespread cellular effects, grouping by their impact on kinetic parameters rather than targeted interfaces.
• Mutations were shown to allosterically tune the kinetics of the GTPase switch cycle.
• Differential sensitivity of biological processes to Gsp1 (RAN) switch cycle kinetics underlies functional specificity.

Conclusions:

• Protein partner binding or distal post-translational modifications may act as allosteric regulators of GTPase switching.
• The findings suggest a general mechanism for regulating biological switches.
• An integrative platform was developed to quantify molecular perturbation effects, aiding in understanding disease mutations.