Allostery without conformation change: modelling protein dynamics at multiple scales

Area of Science:

• Biophysics
• Structural Biology
• Protein Dynamics

Background:

• Allosteric signaling in proteins is crucial for biological regulation.
• The Monod-Wyman-Changeux (MWC) model explains allostery via conformational shifts.
• Cooper and Dryden proposed an alternative: allostery via modulation of thermal fluctuations.

Purpose of the Study:

• To theoretically identify structural requirements for fluctuation-induced allostery.
• To extend coarse-grained models to more detailed protein dynamics.
• To understand the physical basis of allosteric signaling beyond conformational changes.

Main Methods:

• Theoretical modeling approach, progressing from coarse-grained to detailed representations.
• Analysis of protein elastic properties and their relationship to dynamics.
• Review and extension of existing theoretical frameworks for allostery.

Main Results:

• A strongly inhomogeneous elastic modulus is a fundamental requirement for fluctuation-induced allostery.
• Real proteins often exhibit this property, with rigid domains connected by flexible interfaces.
• This inhomogeneous elasticity supports allosteric signaling through amplitude modulation of thermal fluctuations.

Conclusions:

• Protein dynamics, specifically thermal fluctuations, can mediate allosteric signaling.
• Inhomogeneous elastic modulus is a critical structural determinant for this mechanism.
• This provides a complementary perspective to traditional allostery models like MWC.