Propagated Perturbations from a Peripheral Mutation Show Interactions Supporting WW Domain Thermostability

Area of Science:

• Protein structure and dynamics
• Biophysics
• Molecular biology

Background:

• Inter-residue interactions are vital for protein stability and allosteric communication.
• Predicting the impact of mutations on protein function remains a significant challenge in molecular biology.

Purpose of the Study:

• To investigate the molecular basis for the unexpected loss of thermostability caused by a peripheral mutation in the Pin1 WW domain.
• To understand how mutations propagate conformational changes and affect protein cooperative responses.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy to study structural and dynamic changes.
• Microsecond molecular dynamics (MD) simulations to model protein behavior and interactions.

Main Results:

• A single surface mutation (Q33E) in the Pin1 WW domain led to a significant loss of thermostability.
• NMR studies revealed that the mutation caused reorganizations of electrostatic and hydrophobic interactions, leading to propagated conformational perturbations.
• MD simulations indicated that the wild-type protein's stability depends on couplings between a surface electrostatic network and a hydrophobic core, which are disrupted by the Q33E mutation.

Conclusions:

• The study demonstrates the cooperative response of the Pin1 WW domain to external perturbations, consistent with its allosteric behavior.
• Predictive models of mutation consequences should consider the interplay of multiple interaction types, not just single dominant forces.
• Understanding these complex couplings is essential for accurately predicting protein mutational landscapes and designing proteins with desired stability and function.