# Parsimonious evolutionary scenario for the origin of allostery and coevolution patterns in proteins

## TL;DR

This paper proposes an evolutionary scenario where proteins develop allostery and coevolution patterns as by-products of selection for discriminative ligand binding, driven by conformational changes and physical constraints.

## Contribution

It introduces a parsimonious evolutionary model linking allostery, coevolution, and ligand discrimination, supported by a physical model and testable experimental predictions.

## Key findings

- Proteins' allostery and coevolution patterns can arise as evolutionary spandrels.
- Conformational changes are essential for discriminative ligand binding.
- Most coevolving residues are related to thermal stability, not direct contact.

## Abstract

Proteins display generic properties that are challenging to explain by direct selection, notably allostery, the capacity to be regulated through long-range effects, and evolvability, the capacity to adapt to new selective pressures. An evolutionary scenario is proposed where proteins acquire these two features indirectly as a by-product of their selection for a more fundamental property, exquisite discrimination, the capacity to bind discriminatively very similar ligands. Achieving this task is shown to typically require proteins to undergo a conformational change. We argue that physical and evolutionary constraints impel this change to be controlled by a group of sites extending from the binding site. Proteins can thus acquire a latent potential for allosteric regulation and evolutionary adaptation because of long-range effects that initially arise as evolutionary spandrels. This scenario accounts for the groups of conserved and coevolving residues observed in multiple sequence alignments. However, we propose that most pairs of coevolving and contacting residues inferred from such alignments have a different origin, related to thermal stability. A physical model is presented that illustrates this evolutionary scenario and its implications. The scenario can be implemented in experiments of protein evolution to directly test its predictions.