Biology subjects

Botting, J. M.

Publications and source records attributed to Botting, J. M..

3 recordsLinked to original sources

bioRxiv2025

The architecture, assembly, and evolution of a complex flagellar motor

Bacterial flagella drive motility in many species, likely including the last bacterial common ancestor 1,2. Knowledge of flagellar assembly and function has mainly come from studies of Escherichia coli and Salmonella enterica, which have simple flagellar motors 3-7. However, most flagellated bacteria possess complex motors with unique, species-specific adaptations whose mechanisms and evolution remain largely unexplored 8-10. Here, we deploy a multidisciplinary approach to build a near-complete model of the flagellar motor in Campylobacter jejuni, revealing its remarkable complexity in architecture and composition. We identify an E-ring around the MS-ring, a periplasmic cage with two distinctive conformations, and an intricate interaction network between the E-ring and cage. These scaffolds play critical roles in stabilizing and regulating 17 torque-generating stator complexes for optimal motility. In-depth evolutionary analyses uncover the ancient origin and prevalence of the E-ring in flagellated species of the domain Bacteria as well as a unique exaptation of type IV pili components PilMNOPQF in the ancestral motor of the phylum Campylobacterota. Collectively, our studies reveal novel mechanisms of assembly and function in complex flagellar motors and shed light on the evolution of flagella and modern bacterial species.

microbiology↗

bioRxiv2024

Saccharibacteria deploy two distinct Type IV pili, driving episymbiosis, host competition, and twitching motility

All cultivated Patescibacteria, or CPR, exist as obligate episymbionts on other microbes. Despite being ubiquitous in mammals and environmentally, molecular mechanisms of host identification and binding amongst ultrasmall bacterial episymbionts are largely unknown. Type 4 pili (T4P) are well conserved in this group and predicted to facilitate symbiotic interactions. To test this, we targeted T4P pilin genes in Saccharibacteria Nanosynbacter lyticus strain TM7x to assess their essentiality and roles in symbiosis. Our results revealed that N. lyticus assembles two distinct T4P, a non-essential thin pili that has the smallest diameter of any T4P and contributes to host-binding, episymbiont growth, and competitive fitness relative to other Saccharibacteria, and an essential thick pili whose functions include twitching motility. Identification of lectin-like minor pilins and modification of host cell walls suggest glycan binding mechanisms. Collectively our findings demonstrate that Saccharibacteria encode unique extracellular pili that are vital mediators of their underexplored episymbiotic lifestyle.

microbiology↗

bioRxiv2022

Helicobacter pylori FlgV forms a flagellar motor ring structure required for optimal motility

The bacterium Helicobacter pylori has a large flagellar motor that generates significantly higher torque than the archetypical Escherichia coli motor. To understand how H. pylori navigates the viscous environment of the stomach, it is essential to establish how specific motor components contribute to efficient motility. We show here that the protein FlgV, required for motility in Campylobacter jejuni, forms a novel ring associated with the MS and C rings in H. pylori. Deletion of flgV from H. pylori B128 or a highly motile variant of H. pylori G27 (G27M) resulted in reduced motility in soft agar medium. Based on comparative analyses of in-situ flagellar motor structures of H. pylori wild-type and {Delta}flgV mutants, the reduced motility of the {Delta}flgV mutants and the location of the FlgV ring suggest it stabilizes interactions between the MS and C rings and/or plays a role in switching the direction of flagellar rotation. Overall, these results identify a novel motor accessory likely adapted to promote flagellar function for bacterial colonization of high-load environments such as the gastric mucosa.

microbiology↗