A Tad-like apparatus is required for contact-dependent prey killing in predatory social bacteria.

Sofiene Seef,Rikesh Jain,Romain Mercier,Gael Brasseur,Laetitia My,Bianca H Habermann,Julien Herrou,Paul De Boissier,Eric Cascales,Tâm Mignot,Donovan Robert

doi:10.7554/elife.72409

Abstract

Myxococcus xanthus, a soil bacterium, predates collectively using motility to invade prey colonies. Prey lysis is mostly thought to rely on secreted factors, cocktails of antibiotics and enzymes, and direct contact with Myxococcus cells. In this study, we show that on surfaces the coupling of A-motility and contact-dependent killing is the central predatory mechanism driving effective prey colony invasion and consumption. At the molecular level, contact-dependent killing involves a newly discovered type IV filament-like machinery (Kil) that both promotes motility arrest and prey cell plasmolysis. In this process, Kil proteins assemble at the predator-prey contact site, suggesting that they allow tight contact with prey cells for their intoxication. Kil-like systems form a new class of Tad-like machineries in predatory bacteria, suggesting a conserved function in predator-prey interactions. This study further reveals a novel cell-cell interaction function for bacterial pili-like assemblages.

Highlights

Bacterial predators have evolved strategies to consume other microbes as a nutrient source
Social (S)-motility is a form of bacterial ‘twitching’ motility that uses so-called Type IV pili (TFP) acting at the bacterial pole (Mercier et al, 2020)
S-motility promotes the coordinated movements of Myxococcus cells within large cell groups due to interaction with a self-secreted extracellular matrix formed of Exo-Polysaccharide (EPS) (Hu et al, 2016; Li et al, 2003; Islam et al, 2020)

Summary

Introduction

Bacterial predators have evolved strategies to consume other microbes as a nutrient source. It is considered that coordinated group movements allow Myxococcus cells to invade prey colonies and consume them via the secretion of a number of diffusible factors, extracellular enzymes, antibiotics, and outer membrane vesicles (Thiery and Kaimer, 2020; Perez et al, 2016; Xiao et al, 2011).

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Conclusion