Zipping and Entanglement in Flagellar Bundle of E. Coli: Role of Motile Cell Body

TL;DR

This study uses numerical and analytical models to explore how flagellar entanglement, hydrodynamics, and cell body movements influence the rapid formation of flagellar bundles in E. coli, revealing the importance of self-organization.

Contribution

The paper introduces a detailed numerical and simplified analytical model showing how flagellar entanglement and cell body movements drive rapid bundle formation in E. coli.

Findings

Flagellar entanglement significantly alters flagellar dynamics.

Bundle formation occurs through a rapid zipping motion.

Hydrodynamic interactions and cell body movements facilitate bundling.

Abstract

The course of a peritrichous bacterium such as E. coli crucially depends on the level of synchronization and self-organization of several rotating flagella. However, the rotation of each flagellum generates counter body movements which in turn affect the flagellar dynamics. Using a detailed numerical model of an E. coli, we demonstrate that flagellar entanglement, besides fluid flow relative to the moving body, dramatically changes the dynamics of flagella from that compared to anchored flagella. In particular, bundle formation occurs through a zipping motion in a remarkably rapid time, affected little by initial flagellar orientation. A simplified analytical model supports our observations. Finally, we illustrate how entanglement, hydrodynamic interactions, and body movement contribute to zipping and bundling.