Cooperatively enhanced reactivity and 'stabilitaxis' of dissociating oligomeric proteins

TL;DR

This paper explores how the reversible assembly and disassembly of oligomeric proteins can enhance their reactivity and lead to a new phenomenon called 'stabilitaxis', affecting their spatial distribution in complex environments.

Contribution

It introduces a generic model showing how dissociating proteins can improve target reactivity and spatial organization through enhanced diffusion and stabilitaxis.

Findings

Reversible dissociation increases reactivity in uniform environments.

Dissociating proteins tend to accumulate in stable regions in non-uniform environments.

The concept of 'stabilitaxis' explains spatial distribution driven by stability gradients.

Abstract

Many functional units in biology, such as enzymes or molecular motors, are composed of several subunits that can reversibly assemble and disassemble. This includes oligomeric proteins composed of several smaller monomers, as well as protein complexes assembled from a few proteins. By studying the generic spatial transport properties of such proteins, we investigate here whether their ability to reversibly associate and dissociate may confer them a functional advantage with respect to non-dissociating proteins. In uniform environments with position-independent association-dissociation, we find that enhanced diffusion in the monomeric state coupled to reassociation into the functional oligomeric form leads to enhanced reactivity with distant targets. In non-uniform environments with position-dependent association-dissociation, caused e.g. by spatial gradients of an inhibiting chemical, we find that dissociating proteins generically tend to accumulate in regions where they are most stable, a process that we term 'stabilitaxis'.