Molecular Assembly Lines in Active Droplets.

Tyler S Harmon,Frank Jülicher

doi:10.1103/physrevlett.128.108102

Abstract

Large protein complexes are assembled from protein subunits to form a specific structure. In our theoretic work, we propose that assembly into the correct structure could be reliably achieved through an assembly line with a specific sequence of assembly steps. Using droplet interfaces to position compartment boundaries, we show that an assembly line can be self-organized by active droplets. As a consequence, assembly steps can be arranged spatially so that a specific order of assembly is achieved and incorrect assembly is strongly suppressed.

Highlights

Large protein complexes are assembled from protein subunits to form a specific structure
We propose that assembly into the correct structure could be reliably achieved through an assembly line with a specific sequence of assembly steps
Using droplet interfaces to position compartment boundaries, we show that an assembly line can be self-organized by active droplets

Summary

Molecular Assembly Lines in Active Droplets

Large protein complexes are assembled from protein subunits to form a specific structure. Alternative strategies based on nonequilibrium assembly could avoid the problems of thermodynamic self-assembly or allow for the assembly of structures that cannot be reached by minimizing the free energy [1,11,14] This can be achieved when components assemble in a specific temporal order. We ask whether reliable and rapid assembly of complexes with a specific structure can be achieved in steady state where components flow in and complexes flow out We show that this is possible in a self-organized assembly line. We present the theory of nonequilibrium complex formation by a self-organized assembly line These emerge as patterns in reaction-diffusion systems that are confined in droplets. The spatial arrangement of different assembly steps defines the temporal order in which subunits are added to the complex This process can occur at steady state with a constant influx of subunits and constant outflux of finished complexes.

Published by the American Physical Society

In spherical coordinates we define the total association flux as