A comprehensive ensemble model for comparing the allosteric effect of ordered and disordered proteins.

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Intrinsically disordered proteins/regions (IDPs/IDRs) are common in allosteric regulation.
• Previously, intrinsic disorder was thought to enhance allosteric coupling.
• The precise role of IDPs/IDRs in allosteric mechanisms remains debated.

Purpose of the Study:

• To develop a comprehensive ensemble model comparing order-order and disorder-order transitions in allosteric effects.
• To elucidate the complex role of IDPs/IDRs in regulatory proteins.
• To provide insights for the rational design of allosteric drugs.

Main Methods:

• Development of a comprehensive ensemble model.
• Comparison of Monod-Wyman-Changeux (MWC) pathway (order-order transition) and the allosteric effect (EAM) pathway (disorder-order transition).
• Derivation of an analytic formula for maximal allosteric coupling response.

Main Results:

• The MWC pathway (order-order transition) demonstrates a higher probability in allosteric regulation compared to the EAM pathway (disorder-order transition).
• This suggests a more intricate function for IDPs/IDRs in regulatory proteins than previously assumed.
• An analytic formula revealed that extreme stability or instability of protein states is detrimental to allosteric function.

Conclusions:

• The study reveals a complex, non-uniform role for intrinsically disordered proteins in allosteric regulation.
• Order-order transitions are more likely than disorder-order transitions in allosteric mechanisms.
• Understanding the balance of protein stability is crucial for designing effective allosteric drugs.