Multibody simulation of adhesion pili

TL;DR

This paper introduces a coarse-grained multibody model to simulate the mechanical behavior of bacterial adhesion pili, accurately capturing their force-extension response and effects of external forces and antibodies.

Contribution

The novel multibody model effectively reproduces experimental force-extension behaviors of bacterial pili, including antibody effects, enhancing understanding of bacterial adhesion mechanics.

Findings

Model matches experimental force-extension data

Reproduces effects of anti-shaft antibodies

Provides insights into pilus unwinding dynamics

Abstract

We present a coarse grained rigid multibody model of a subunit assembled helix-like polymer, e.g., adhesion pili expressed by bacteria, that is capable of describing the polymers force-extension response. With building blocks representing individual subunits the model appropriately describes the complex behavior of pili expressed by the gram-negative uropathogenic Escherichia coli bacteria under the action of an external force. Numerical simulations show that the dynamics of the model, which include both the effects of unwinding and rewinding, are in good quantitative agreement with the characteristic force-extension response as observed experimentally for type 1 and P pili. By tuning the model, it is also possible to reproduce the force-extension response in the presence of anti-shaft antibodies, which dramatically changes the mechanical properties. Thus, the model and the results in this work give enhanced understanding of how a pilus unwinds under action of external forces and provide new perspective of the complex bacterial adhesion processes.