Self-assembly of artificial microtubules

TL;DR

This study uses molecular dynamics simulations to explore how designed monomers self-assemble into tubules, revealing conditions for optimal formation and unexpected helical structures, advancing the design of artificial microtubules.

Contribution

It introduces a model for artificial microtubule self-assembly, analyzes the assembly process, and maps the structural phase diagram across interaction strengths.

Findings

Optimal interaction strength range for tubule formation

Helical tubules form despite nonhelical monomer design

Detailed dynamics of self-assembly process

Abstract

Understanding the complex self-assembly of biomacromolecules is a major outstanding question. Microtubules are one example of a biopolymer that possesses characteristics quite distinct from standard synthetic polymers that are derived from its hierarchical structure. In order to understand how to design and build artificial polymers that possess features similar to those of microtubules, we have initially studied the self-assembly of model monomers into a tubule geometry. Our model monomer has a wedge shape with lateral and vertical binding sites that are designed to form tubules. We used molecular dynamics simulations to study the assembly process for a range of binding site interaction strengths. In addition to determining the optimal regime for obtaining tubules, we have calculated a diagram of the structures that form over a wide range of interaction strengths. Unexpectedly, we find that the helical tubules form, even though the monomer geometry is designed for nonhelical tubules. We present the detailed dynamics of the tubule self-assembly process and show that the interaction strengths must be in a limited range to allow rearrangement within clusters. We extended previous theoretical methods to treat our system and to calculate the boundaries between different structures in the diagram.