scholarly journals Type IV Pili Are Required for Virulence, Twitching Motility, and Biofilm Formation of Acidovorax avenae subsp. citrulli

2009 ◽  
Vol 22 (8) ◽  
pp. 909-920 ◽  
Author(s):  
Ofir Bahar ◽  
Tal Goffer ◽  
Saul Burdman
Keyword(s):  
Biofilm Formation ◽  
Host Plants ◽  
Seed Transmission ◽  
Type Iv Pili ◽  
Twitching Motility ◽  
Wild Type ◽  
Type Iv ◽  
Group I ◽  
Tn5 Mutant

Acidovorax avenae subsp. citrulli is the causal agent of bacterial fruit blotch (BFB), a threatening disease of watermelon, melon, and other cucurbits. Despite the economic importance of BFB, relatively little is known about basic aspects of the pathogen's biology and the molecular basis of its interaction with host plants. To identify A. avenae subsp. citrulli genes associated with pathogenicity, we generated a transposon (Tn5) mutant library on the background of strain M6, a group I strain of A. avenae subsp. citrulli, and screened it for reduced virulence by seed-transmission assays with melon. Here, we report the identification of a Tn5 mutant with reduced virulence that is impaired in pilM, which encodes a protein involved in assembly of type IV pili (TFP). Further characterization of this mutant revealed that A. avenae subsp. citrulli requires TFP for twitching motility and wild-type levels of biofilm formation. Significant reductions in virulence and biofilm formation as well as abolishment of twitching were also observed in insertional mutants affected in other TFP genes. We also provide the first evidence that group I strains of A. avenae subsp. citrulli can colonize and move through host xylem vessels.

scholarly journals Biofilm formation by Pseudomonas aeruginosa wild type, flagella and type IV pili mutants

2003 ◽  
Vol 48 (6) ◽  
pp. 1511-1524 ◽  
Author(s):  
Mikkel Klausen ◽  
Arne Heydorn ◽  
Paula Ragas ◽  
Lotte Lambertsen ◽  
Anders Aaes-Jørgensen ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Type Iv Pili ◽  
Wild Type ◽  
Type Iv

scholarly journals Ralstonia solanacearum Needs Flp Pili for Virulence on Potato

2012 ◽  
Vol 25 (4) ◽  
pp. 546-556 ◽  
Author(s):  
Charles K. Wairuri ◽  
Jacquie E. van der Waals ◽  
Antoinette van Schalkwyk ◽  
Jacques Theron
Keyword(s):  
Ralstonia Solanacearum ◽  
Type Iv Pili ◽  
Periodontal Pathogen ◽  
Wild Type ◽  
In Planta ◽  
Phytopathogenic Bacterium ◽  
Type Iv ◽  
Plant Pathogenesis

Type IV pili are virulence factors in various bacteria. Several subclasses of type IV pili have been described according to the characteristics of the structural prepilin subunit. Although type IVa pili have been implicated in the virulence of Ralstonia solanacearum, type IVb pili have not previously been described in this plant pathogen. Here, we report the characterization of two distinct tad loci in the R. solanacearum genome. The tad genes encode functions necessary for biogenesis of the Flp subfamily of type IVb pili initially described for the periodontal pathogen Aggregatibacter actinomycetemcomitans. To determine the role of the tad loci in R. solanacearum virulence, we mutated the tadA2 gene located in the megaplasmid that encodes a predicted NTPase previously reported to function as the energizer for Flp pilus biogenesis. Characterization of the tadA2 mutant revealed that it was not growth impaired in vitro or in planta, produced wild-type levels of exopolysaccharide galactosamine, and exhibited swimming and twitching motility comparable with the wild-type strain. However, the tadA2 mutant was impaired in its ability to cause wilting of potato plants. This is the first report where type IVb pili in a phytopathogenic bacterium contribute significantly to plant pathogenesis.

scholarly journals FimX, a Multidomain Protein Connecting EnvironmentalSignals to Twitching Motility in Pseudomonasaeruginosa

2003 ◽  
Vol 185 (24) ◽  
pp. 7068-7076 ◽  
Author(s):  
Bixing Huang ◽  
Cynthia B. Whitchurch ◽  
John S. Mattick
Keyword(s):  
Fluorescent Protein ◽  
Response Regulator ◽  
Type Iv Pili ◽  
Environmental Cues ◽  
Twitching Motility ◽  
Wild Type ◽  
Protein Fusion ◽  
Type Iv ◽  
Low Levels ◽  
Signal Transduction Proteins

ABSTRACT Twitching motility is a form of surface translocation mediated by the extension, tethering, and retraction of type IV pili. Three independent Tn5-B21 mutations of Pseudomonas aeruginosa with reduced twitching motility were identified in a new locus which encodes a predicted protein of unknown function annotated PA4959 in the P. aeruginosa genome sequence. Complementation of these mutants with the wild-type PA4959 gene, which we designated fimX, restored normal twitching motility. fimX mutants were found to express normal levels of pilin and remained sensitive to pilus-specific bacteriophages, but they exhibited very low levels of surface pili, suggesting that normal pilus function was impaired. The fimX gene product has a molecular weight of 76,000 and contains four predicted domains that are commonly found in signal transduction proteins: a putative response regulator (CheY-like) domain, a PAS-PAC domain (commonly involved in environmental sensing), and DUF1 (or GGDEF) and DUF2 (or EAL) domains, which are thought to be involved in cyclic di-GMP metabolism. Red fluorescent protein fusion experiments showed that FimX is located at one pole of the cell via sequences adjacent to its CheY-like domain. Twitching motility in fimX mutants was found to respond relatively normally to a range of environmental factors but could not be stimulated by tryptone and mucin. These data suggest that fimX is involved in the regulation of twitching motility in response to environmental cues.

scholarly journals Non-motile subpopulations of Pseudomonas aeruginosa repress flagellar motility in motile cells through a type IV pili- and Pel-dependent mechanism

2021 ◽  
Author(s):  
Kimberley A. Lewis ◽  
Danielle M Vermilyea ◽  
Shanice S Webster ◽  
Jaime de Anda ◽  
Gerard Wong ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Total Population ◽  
Type Iv Pili ◽  
External Factors ◽  
Flagellar Motility ◽  
Wild Type ◽  
Type Iv ◽  
Motile Cells ◽  
Flagellum Biosynthesis ◽  
Dependent Mechanism

The downregulation of P. aeruginosa flagellar motility is a key event in biofilm formation, host-colonization, and the formation of microbial communities, but the external factors that repress motility are not well understood. Here, we report that under swarming conditions, motility can be repressed by cells that are non-motile due to the absence of a flagellum or flagellar rotation. Non-motile cells, due to mutations that prevent either flagellum biosynthesis or rotation, present at 5% of the total population suppressed swarming of wild-type cells under the conditions tested in this study. Non-motile cells required functional type IV pili and the ability to produce the Pel exopolysaccharide to suppress swarming by the motile wild type. In contrast, motile cells required only type IV pili, but not Pel production, in order for swarming to be repressed by non-motile cells. We hypothesize that interactions between motile and non-motile cells may enhance the formation of sessile communities including those involving multiple genotypes, phenotypically-diverse cells, and perhaps other species.

scholarly journals Association Between Loss of Type IV Pilus Synthesis Ability and Phenotypic Variation in the Cucurbit Pathogenic Bacterium Acidovorax citrulli

2018 ◽  
Vol 31 (5) ◽  
pp. 548-559 ◽  
Author(s):  
Tally Rosenberg ◽  
Bolaji Babajide Salam ◽  
Saul Burdman
Keyword(s):  
Phenotypic Variation ◽  
Seed Transmission ◽  
Colony Morphology ◽  
Twitching Motility ◽  
Wild Type ◽  
Type Iv ◽  
Acidovorax Citrulli ◽  
Transmission Electron ◽  
Transposon Mutants ◽  
Transposon Insertions

Acidovorax citrulli is the causal agent of bacterial fruit blotch of cucurbits. We have shown that functional type IV pili (T4P) are required for full virulence of this bacterium. To identify A. citrulli genes required for T4P activity, we screened a library of about 10,000 transposon mutants of A. citrulli M6 for altered T4P-mediated twitching motility. This screen led to the identification of 50 mutants impaired in twitching ability due to transposon insertions into 20 different genes. Representative mutants with disruptions in these genes were further characterized. All mutants were compromised in their virulence in seed transmission and stem inoculation assays and had reduced biofilm formation ability relative to wild-type M6. When grown on nutrient agar, most mutants produced colonies with a translucent and fuzzy appearance, in contrast to the opaque and smooth appearance of wild-type colonies. The colony morphology of these mutants was identical to that of previously reported phenotypic variants of strain M6. The exceptions were M6 mutants disrupted in genes tonB, pilT, pilW, and pilX that exhibited typical wild-type colony morphology, although lacking twitching haloes surrounding the colony. Transmission electron microscopy revealed that most mutants lacked the ability to produce T4P. The exceptions were mutants with disruptions in tonB, pilT, pilW, and pilX genes that were shown to produce these appendages. These findings support the idea that colony phenotypic variation in A. citrulli is determined by the lack of ability to synthesize T4P but not by lack of T4P functionality.

scholarly journals Type I and type IV pili of Xylella fastidiosa affect twitching motility, biofilm formation and cell–cell aggregation

Microbiology ◽  
2007 ◽  
Vol 153 (3) ◽  
pp. 719-726 ◽  
Author(s):  
Yaxin. Li ◽  
Guixia. Hao ◽  
Cheryl D. Galvani ◽  
Yizhi Meng ◽  
Leonardo De La. Fuente ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Xylella Fastidiosa ◽  
Cell Aggregation ◽  
Type Iv Pili ◽  
Type I ◽  
Twitching Motility ◽  
Type Iv ◽  
Cell Cell

scholarly journals Pseudomonas aeruginosa Exhibits Directed Twitching Motility Up Phosphatidylethanolamine Gradients

2001 ◽  
Vol 183 (2) ◽  
pp. 763-767 ◽  
Author(s):  
Daniel B. Kearns ◽  
Jayne Robinson ◽  
Lawrence J. Shimkets
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Solid Surfaces ◽  
Twitching Motility ◽  
Wild Type ◽  
Directed Movement ◽  
Endogenous Factors ◽  
Type Iv ◽  
Cell Velocity ◽  
Dependent Form

ABSTRACT Pseudomonas aeruginosa translocates over solid surfaces by a type IV pilus-dependent form of multicellular motility known as twitching. We wondered whether cells utilize endogenous factors to organize twitching, and we purified from wild-type cells a lipid that caused directed movement. Wild-type P. aeruginosa, but not a pilJ pilus-deficient mutant, showed biased movement up gradients of phosphatidylethanolamine (PE) established in agar. Activity was related to the fatty acid composition of the lipid, as two synthetic PE species, dilauroyl and dioleoyl PE, were capable of directing P. aeruginosa motility while many other species were inactive. P. aeruginosa PE did not contain either laurate or oleate, implying that the native attractant species contains different fatty acids. Uniform concentrations of PE increased cell velocity, suggesting that chemokinesis may be at least partly responsible for directed movement. We speculate that PE-directed twitching motility may be involved in biofilm formation and pathogenesis.

scholarly journals Type IV Pili Can Mediate Bacterial Motility within Epithelial Cells

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Vincent Nieto ◽  
Abby R. Kroken ◽  
Melinda R. Grosser ◽  
Benjamin E. Smith ◽  
Matteo M. E. Metruccio ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Epithelial Cells ◽  
Host Cell ◽  
Type Iv Pili ◽  
Fluorescent Imaging ◽  
Bacterial Motility ◽  
Twitching Motility ◽  
Wild Type ◽  
Content Type ◽  
Type Iv

ABSTRACT Pseudomonas aeruginosa is among bacterial pathogens capable of twitching motility, a form of surface-associated movement dependent on type IV pili (T4P). Previously, we showed that T4P and twitching were required for P. aeruginosa to cause disease in a murine model of corneal infection, to traverse human corneal epithelial multilayers, and to efficiently exit invaded epithelial cells. Here, we used live wide-field fluorescent imaging combined with quantitative image analysis to explore how twitching contributes to epithelial cell egress. Results using time-lapse imaging of cells infected with wild-type PAO1 showed that cytoplasmic bacteria slowly disseminated throughout the cytosol at a median speed of >0.05 μm s−1 while dividing intracellularly. Similar results were obtained with flagellin (fliC) and flagellum assembly (flhA) mutants, thereby excluding swimming, swarming, and sliding as mechanisms. In contrast, pilA mutants (lacking T4P) and pilT mutants (twitching motility defective) appeared stationary and accumulated in expanding aggregates during intracellular division. Transmission electron microscopy confirmed that these mutants were not trapped within membrane-bound cytosolic compartments. For the wild type, dissemination in the cytosol was not prevented by the depolymerization of actin filaments using latrunculin A and/or the disruption of microtubules using nocodazole. Together, these findings illustrate a novel form of intracellular bacterial motility differing from previously described mechanisms in being directly driven by bacterial motility appendages (T4P) and not depending on polymerized host actin or microtubules. IMPORTANCE Host cell invasion can contribute to disease pathogenesis by the opportunistic pathogen Pseudomonas aeruginosa. Previously, we showed that the type III secretion system (T3SS) of invasive P. aeruginosa strains modulates cell entry and subsequent escape from vacuolar trafficking to host lysosomes. However, we also showed that mutants lacking either type IV pili (T4P) or T4P-dependent twitching motility (i) were defective in traversing cell multilayers, (ii) caused less pathology in vivo, and (iii) had a reduced capacity to exit invaded cells. Here, we report that after vacuolar escape, intracellular P. aeruginosa can use T4P-dependent twitching motility to disseminate throughout the host cell cytoplasm. We further show that this strategy for intracellular dissemination does not depend on flagellin and resists both host actin and host microtubule disruption. This differs from mechanisms used by previously studied pathogens that utilize either host actin or microtubules for intracellular dissemination independently of microbe motility appendages.

scholarly journals tonB3 Is Required for Normal Twitching Motility and Extracellular Assembly of Type IV Pili

2004 ◽  
Vol 186 (13) ◽  
pp. 4387-4389 ◽  
Author(s):  
Bixing Huang ◽  
Kelin Ru ◽  
Zheng Yuan ◽  
Cynthia B. Whitchurch ◽  
John S. Mattick
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iv Pili ◽  
Twitching Motility ◽  
Wild Type ◽  
Type Iv

ABSTRACT Three mutants with Tn5-B21 insertion in tonB3 (PA0406) of Pseudomonas aeruginosa exhibited defective twitching motility and reduced assembly of extracellular pili. These defects could be complemented with wild-type tonB3.

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