Bacterial flagella: twist and stick, or dodge across the kingdoms.

Yannick Rossez,Ashleigh Holmes,Eliza B Wolfson,David L Gally,Nicola J Holden,James B Bliska

doi:10.1371/journal.ppat.1004483

Yannick Rossez, Ashleigh Holmes + Show 4 more

Open Access

https://doi.org/10.1371/journal.ppat.1004483

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Abstract

The flagellum organelle is an intricate multiprotein assembly best known for its rotational propulsion of bacteria. However, recent studies have expanded our knowledge of other functions in pathogenic contexts, particularly adherence and immune modulation, e.g., for Salmonella enterica, Campylobacter jejuni, Pseudomonas aeruginosa, and Escherichia coli. Flagella-mediated adherence is important in host colonisation for several plant and animal pathogens, but the specific interactions that promote flagella binding to such diverse host tissues has remained elusive. Recent work has shown that the organelles act like probes that find favourable surface topologies to initiate binding. An emerging theme is that more general properties, such as ionic charge of repetitive binding epitopes and rotational force, allow interactions with plasma membrane components. At the same time, flagellin monomers are important inducers of plant and animal innate immunity: variation in their recognition impacts the course and outcome of infections in hosts from both kingdoms. Bacteria have evolved different strategies to evade or even promote this specific recognition, with some important differences shown for phytopathogens. These studies have provided a wider appreciation of the functions of bacterial flagella in the context of both plant and animal reservoirs.

Highlights

The prokaryotic flagellum is best known as a motility organelle responsible for bacterial movement and necessary for chemotaxis [1]
Flagella from a variety of bacteria have been shown to bind to a diverse array of animal and plant substrates, and this review focuses on recent advances in our understanding of how flagella impact host-microbe interactions
Flagella from attaching and effacing bacteria enterohaemorrhagic E. coli (EHEC) O157:H7 and enteropathogenic E. coli (EPEC) O127:H6 have both been shown to be involved in the adherence to porcine gastric mucins and bovine primary intestinal epithelial cells and explants [21,22]

Summary

Introduction

The prokaryotic flagellum is best known as a motility organelle responsible for bacterial movement and necessary for chemotaxis [1]. Adherence is described for intact flagella, while aspects of recognition and evasion relate to the flagellin protein. A role for flagella-mediated adherence has been demonstrated in many different plant species and animal infection models, for both pathogenic and opportunistic bacteria [4,5]. A motility deficient mutant (motAB) was not deleteriously affected in adherence compared to the parental strain, demonstrating that flagellamediated binding did not require chemotaxis or flagella rotation.

Results

Conclusion