DNA-uptake pili of Vibrio cholerae are required for chitin colonization and capable of kin recognition via sequence-specific self-interaction

Abstract

How bacteria colonise surfaces and how they distinguish the individuals around them are fundamental biological questions. Type IV pili are a widespread and multi-purpose class of cell surface polymers. Here we directly visualise the DNA-uptake pilus of Vibrio cholerae, which is produced specifically during growth upon its natural habitat - chitinous surfaces. As predicted, these pili are highly dynamic and retract prior to DNA-uptake during competence for natural transformation. Interestingly, DNA-uptake pili can also self-interact to mediate auto-aggregation. This capability is conserved in disease-causing pandemic strains, which typically encode the same major pilin subunit, PilA. Unexpectedly, however, we discovered that extensive strain-to-strain variability in PilA, present in environmental isolates, creates a set of highly specific interactions, enabling cells producing pili composed of different PilA subunits to distinguish between one another. We go on to show that DNA-uptake pili bind to chitinous surfaces, are required for chitin colonisation under flow, and that pili capable of self-interaction connect cells on chitin within dense pili networks. Our results suggest a model whereby DNA-uptake pili function to promote inter-bacterial interactions during surface colonisation. Moreover, they provide evidence that type IV pili could offer a simple and potentially widespread mechanism for bacterial kin recognition.

CryoEM structure of the type IVa pilus secretin required for natural competence in Vibrio cholerae

“…The T3SS uses a "needle and syringe" to export cytosolic effector proteins outside of the cell, or directly into another cell. The T4P have a broad range of functionality, including DNA uptake, twitching motility, biofilm formation, and adhesion 15,16,30,37 . During natural transformation, the T4aP extends and retracts a filament to take up DNA cargo.…”

The polar Ras-like GTPase MglA activates type IV pilus via SgmX to enable twitching motility in Myxococcus xanthus

“…To investigate how MglA-GTP activates S-motility, we aimed to image Tfpa-pilin filament dynamics directly in single twitching cells. For that purpose, we adapted a recently described pilin cysteine-labeling method that involves adding extracellularly cysteine-reactive maleimide fluorescent conjugates; this technique enabled the real-time imaging of Tfps in other bacteria (3,31,32). Among several cysteine substitutions tested in the major pilin PilA subunit, we found one substitution, PilA D71C , that allowed us to label pilin filaments when expressed under the control of the pilA promoter (P pilA ).…”

“…Tfps are particularly widespread in bacteria and play key roles in adaptation, development, and virulence (1,2). While Tfps exhibit highly conserved macromolecular structures, they support very diverse cellular functions, including host cell adhesion, extracellular DNA import (competence), kin recognition, and cell motility (twitching) (1)(2)(3). Twitching motility leads to the remarkable formation of coordinated cell groups, in which hundreds of cells move in a cooperative manner similar to swarming motility in flagellated bacteria (4,5).…”

Labile Dissolved Organic Matter Compound Characteristics Select for Divergence in Marine Bacterial Activity and Transcription

“…The most striking feature of the polysaccharide non-core was the pronounced expression of genes encoding motility and chemotaxis, in addition to type IV pili genes. Type IV pili can have a multitude of functions (e.g., adherence and aggregation, motility, biofilm formation, competence and conjugation, protein secretion) (Chen and Dubnau, 2004;Giltner et al, 2012;Maier and Wong, 2015), and can be involved in inter-bacterial interactions during surface colonization of the polymer chitin (Adams et al, 2019). The dominant expression of Alteromonadales (Colwellia sp.…”