External Stresses Affect Gonococcal Type 4 Pilus Dynamics

Kraus-Römer, Sebastian; Wielert, Isabelle; Rathmann, Isabel; Großbach, Jan; Maier, Berenike

doi:10.3389/fmicb.2022.839711

Cited by 7 publications

(6 citation statements)

References 61 publications

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“…By contrast to P. aeruginosa, N. gonorrhoeae uses type 4 pilus (T4P)-driven motility to self-aggregate into surface-attached spherical microcolonies consisting of thousands of cells within a few minutes [18][19][20]. T4P are extracellular polymers that continuously elongate and retract [21][22][23][24]. T4P dynamics are crucial for the structure of gonococcal colonies; a tug-ofwar mechanism fluidizes the colonies, introducing local liquid-like order and causing colonies to form spheres [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Collective polarization dynamics in bacterial colonies signify the occurrence of distinct subpopulations

et al. 2023

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Membrane potential in bacterial systems has been shown to be dynamic and tightly related to survivability at the single-cell level. However, little is known about spatiotemporal patterns of membrane potential in bacterial colonies and biofilms. Here, we discovered a transition from uncorrelated to collective dynamics within colonies formed by the human pathogen Neisseria gonorrhoeae. In freshly assembled colonies, polarization is heterogeneous with instances of transient and uncorrelated hyper- or depolarization of individual cells. As colonies reach a critical size, the polarization behavior transitions to collective dynamics: A hyperpolarized shell forms at the center, travels radially outward, and halts several micrometers from the colony periphery. Once the shell has passed, we detect an influx of potassium correlated with depolarization. Transient hyperpolarization also demarks the transition from volume to surface growth. By combining simulations and the use of an alternative electron acceptor for the respiratory chain, we provide strong evidence that local oxygen gradients shape the collective polarization dynamics. Finally, we show that within the hyperpolarized shell, tolerance against aminoglycoside antibiotics increases. These findings highlight that the polarization pattern can signify the differentiation into distinct subpopulations with different growth rates and antibiotic tolerance.

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Section: Introductionmentioning

confidence: 99%

Collective polarization dynamics in bacterial colonies signify the occurrence of distinct subpopulations

et al. 2023

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“…In this study, we focus on the following T4P-related functions: twitching motility, generation of attractive forces between cells, colony formation, and antibiotic tolerance. Twitching motility is a mode of surface motility driven by cycles of T4P elongation, surface attachment, and retraction [17,2,18]. N. gonorrhoeae follows a tug-of-war mechanism during twitching motility [19,20] and, as a consequence, gonococcal motility can be described as a correlated random walk.…”

Section: Introductionmentioning

confidence: 99%

Antigenic variation impacts gonococcal lifestyle and antibiotic tolerance by modulating interbacterial forces

Wielert,

Kraus-Römer,

Volkmann

et al. 2023

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Type 4 pili (T4P) are multifunctional filaments involved in adhesion, surface motility, colony formation, and horizontal gene transfer. These extracellular polymers are surface-exposed and, therefore, act as antigens. The human pathogen Neisseria gonorrhoeae uses pilin antigenic variation to escape immune surveillance, yet it is unclear how antigenic variation impacts other functions of T4P. Here, we addressed this question by replacing the major pilin of a laboratory strain of N. gonorrhoeae with pilins from clinical isolates. Structural predictions reveal filament features that vary from one strain to the next, with the potential to impact pilus:pilus interactions. Using a combination of laser tweezers, electron microscopy, and advanced image analysis, we explore the phenotypic consequences of these structural changes. We reveal that strains differing only in their major pilin sequence vary substantially in their attractive forces, which we attribute to variations in the stereochemistry of the T4P filament. In liquid culture, strongly interacting bacteria form colonies while weakly interacting bacteria retain a planktonic lifestyle. We show that lifestyle strongly affects growth kinetics and antibiotic tolerance. In the absence of external stresses, planktonic bacteria grow faster than colony-forming bacteria. In the presence of the antibiotics ceftriaxone and ciprofloxacin, the killing kinetics indicate strongly increased tolerance of colony-forming strains. We propose that pilin antigenic variation produces a mixed population containing variants optimized for growth, colonization, or survivability under external stress. Different environments select different variants, ensuring the survival and reproduction of the population as a whole.

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“…One study used time-lapse microscopy of fluorescent DNA uptake by N. gonorrhoeae to demonstrate that ComE colocalizes with DNA during import [24], yet the authors noted that no association of DNA with T4P-like structures was observed despite experiments being performed in a ΔpilV background with heightened expression of pilus-localized ComP. This may result from the fact that rapid retraction of pili [33,49] and sequestration of associated DNA into the periplasm can cause highly transient visibility of T4P-DNA complexes [50]. Here, we quantified DNA binding to in situ gonococcal T4P fibres via direct visualization of binding complexes with fluorescence microscopy in order to unequivocally demonstrate the sequence-specific, comP-dependent DNA binding capacity of elongated T4P fibres.…”

Section: Introductionmentioning

confidence: 99%

Direct visualization of sequence-specific DNA binding by gonococcal type IV pili

2022

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Neisseria gonorrhoeae , the causative agent of gonorrhoea, is a major burden on global healthcare systems, with an estimated ~80–90 million new global cases annually. This burden is exacerbated by increasing levels of antimicrobial resistance, which has greatly limited viable antimicrobial therapies. Decreasing gonococcal drug susceptibility has been driven largely by accumulation of chromosomal resistance determinants, which can be acquired through natural transformation, whereby DNA in the extracellular milieu is imported into cells and incorporated into the genome by homologous recombination. N. gonorrhoeae possesses a specialized system for DNA uptake, which strongly biases transformation in favour of DNA from closely related bacteria by recognizing a 10–12 bp DNA uptake sequence (DUS) motif, which is highly overrepresented in their chromosomal DNA. This process relies on numerous proteins, including the DUS-specific receptor ComP, which assemble retractile protein filaments termed type IV pili (T4P) extending from the cell surface, and one model for neisserial DNA uptake proposes that these filaments bind DNA in a DUS-dependent manner before retracting to transport DNA into the periplasm. However, conflicting evidence indicates that elongated pilus filaments may not have such a direct role in DNA binding uptake as this model suggests. Here, we quantitatively measured DNA binding to gonococcal T4P fibres by directly visualizing binding complexes with confocal fluorescence microscopy in order to confirm the sequence-specific, comP-dependent DNA binding capacity of elongated T4P fibres. This supports the idea that pilus filaments could be responsible for initially capturing DNA in the first step of sequence-specific DNA uptake.

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External Stresses Affect Gonococcal Type 4 Pilus Dynamics

Cited by 7 publications

References 61 publications

Collective polarization dynamics in bacterial colonies signify the occurrence of distinct subpopulations

Collective polarization dynamics in bacterial colonies signify the occurrence of distinct subpopulations

Antigenic variation impacts gonococcal lifestyle and antibiotic tolerance by modulating interbacterial forces

Direct visualization of sequence-specific DNA binding by gonococcal type IV pili

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