Many-molecule encapsulation by an icosahedral shell

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Abstract

We computationally study how an icosahedral shell assembles around hundreds of molecules. Such a process occurs during the formation of the carboxysome, a bacterial microcompartment that assembles around many copies of the enzymes ribulose 1,5-bisphosphate carboxylase/oxygenase and carbonic anhydrase to facilitate carbon fixation in cyanobacteria. Our simulations identify two classes of assembly pathways leading to encapsulation of many-molecule cargoes. In one, shell assembly proceeds concomitantly with cargo condensation. In the other, the cargo first forms a dense globule; then, shell proteins assemble around and bud from the condensed cargo complex. Although the model is simplified, the simulations predict intermediates and closure mechanisms not accessible in experiments, and show how assembly can be tuned between these two pathways by modulating protein interactions. In addition to elucidating assembly pathways and critical control parameters for microcompartment assembly, our results may guide the reengineering of viruses as nanoreactors that self-assemble around their reactants.

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Jason D Perlmutter

Martin Fisher School of Physics, Brandeis University, Waltham, United States

Competing interests
The authors declare that no competing interests exist.
Farzaneh Mohajerani

Martin Fisher School of Physics, Brandeis University, Waltham, United States

Competing interests
The authors declare that no competing interests exist.
Michael F Hagan

Martin Fisher School of Physics, Brandeis University, Waltham, United States

For correspondence
hagan@brandeis.edu

Competing interests
The authors declare that no competing interests exist.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.