Two type IV pili ofVibrio parahaemolyticusplay different roles in biofilm formation

ABSTRACTPhototrophic biofilms are key to nutrient cycling in natural environments and bioremediation technologies, but few studies describe biofilm formation by pure (axenic) cultures of a phototrophic microbe. The cyanobacteriumSynechocystissp. strain PCC 6803 (hereSynechocystis) is a model microorganism for the study of oxygenic photosynthesis and biofuel production. We report here that wild-type (WT)Synechocystiscaused extensive biofilm formation in a 2,000-liter outdoor nonaxenic photobioreactor under conditions attributed to nutrient limitation. We developed a biofilm assay and found that axenicSynechocystisforms biofilms of cells and extracellular material but only when cells are induced by an environmental signal, such as a reduction in the concentration of growth medium BG11. Mutants lacking cell surface structures, namely type IV pili and the S-layer, do not form biofilms. To further characterize the molecular mechanisms of cell-cell binding bySynechocystis, we also developed a rapid (8-h) axenic aggregation assay. Mutants lacking type IV pili were unable to aggregate, but mutants lacking a homolog to Wza, a protein required for type 1 exopolysaccharide export inEscherichia coli, had a superbinding phenotype. In WT cultures, 1.2× BG11 medium induced aggregation to the same degree as 0.8× BG11 medium. Overall, our data support that Wza-dependent exopolysaccharide is essential to maintain stable, uniform suspensions of WTSynechocystiscells in unmodified growth medium and that this mechanism is counteracted in a pilus-dependent manner under altered BG11 concentrations.IMPORTANCEMicrobes can exist as suspensions of individual cells in liquids and also commonly form multicellular communities attached to surfaces. Surface-attached communities, called biofilms, can confer antibiotic resistance to pathogenic bacteria during infections and establish food webs for global nutrient cycling in the environment. Phototrophic biofilm formation is one of the earliest phenotypes visible in the fossil record, dating back over 3 billion years. Despite the importance and ubiquity of phototrophic biofilms, most of what we know about the molecular mechanisms, genetic regulation, and environmental signals of biofilm formation comes from studies of heterotrophic bacteria. We aim to help bridge this knowledge gap by developing new assays forSynechocystis, a phototrophic cyanobacterium used to study oxygenic photosynthesis and biofuel production. With the aid of these new assays, we contribute to the development ofSynechocystisas a model organism for the study of axenic phototrophic biofilm formation.

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Type IV pili promote early biofilm formation byClostridium difficile

Pathogens and Disease ◽

10.1093/femspd/ftw061 ◽

2016 ◽

Vol 74 (6) ◽

pp. ftw061 ◽

Cited By ~ 25

Author(s):

Grace A. Maldarelli ◽

Kurt H. Piepenbrink ◽

Alison J. Scott ◽

Jeffrey A. Freiberg ◽

Yang Song ◽

...

Keyword(s):

Biofilm Formation ◽

Type Iv Pili ◽

Type Iv

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DNA Binding: a Novel Function of Pseudomonas aeruginosa Type IV Pili

Journal of Bacteriology ◽

10.1128/jb.187.4.1455-1464.2005 ◽

2005 ◽

Vol 187 (4) ◽

pp. 1455-1464 ◽

Cited By ~ 96

Author(s):

Erin J. van Schaik ◽

Carmen L. Giltner ◽

Gerald F. Audette ◽

David W. Keizer ◽

Daisy L. Bautista ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Dna Binding ◽

Biofilm Formation ◽

Quaternary Structure ◽

Natural Transformation ◽

Ex Vivo ◽

Specific Binding ◽

Type Iv Pili ◽

Type Iv ◽

Bacteriophage Infection

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa produces multifunctional, polar, filamentous appendages termed type IV pili. Type IV pili are involved in colonization during infection, twitching motility, biofilm formation, bacteriophage infection, and natural transformation. Electrostatic surface analysis of modeled pilus fibers generated from P. aeruginosa strain PAK, K122-4, and KB-7 pilin monomers suggested that a solvent-exposed band of positive charge may be a common feature of all type IV pili. Several functions of type IV pili, including natural transformation and biofilm formation, involve DNA. We investigated the ability of P. aeruginosa type IV pili to bind DNA. Purified PAK, K122-4, and KB-7 pili were observed to bind both bacterial plasmid and salmon sperm DNA in a concentration-dependent and saturable manner. PAK pili had the highest affinity for DNA, followed by K122-4 and KB-7 pili. DNA binding involved backbone interactions and preferential binding to pyrimidine residues even though there was no evidence of sequence-specific binding. Pilus-mediated DNA binding was a function of the intact pilus and thus required elements present in the quaternary structure. However, binding also involved the pilus tip as tip-specific, but not base-specific, antibodies inhibited DNA binding. The conservation of a Thr residue in all type IV pilin monomers examined to date, along with the electrostatic data, implies that DNA binding is a conserved function of type IV pili. Pilus-mediated DNA binding could be important for biofilm formation both in vivo during an infection and ex vivo on abiotic surfaces.

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Archaeal type IV pili and their involvement in biofilm formation

Frontiers in Microbiology ◽

10.3389/fmicb.2015.00190 ◽

2015 ◽

Vol 06 ◽

Cited By ~ 34

Author(s):

Mechthild Pohlschroder ◽

Rianne N. Esquivel

Keyword(s):

Biofilm Formation ◽

Type Iv Pili ◽

Type Iv

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

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-22-8-0909 ◽

2009 ◽

Vol 22 (8) ◽

pp. 909-920 ◽

Cited By ~ 84

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.

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Contribution of Moraxella catarrhalis Type IV Pili to Nasopharyngeal Colonization and Biofilm Formation

Infection and Immunity ◽

10.1128/iai.00946-07 ◽

2007 ◽

Vol 75 (12) ◽

pp. 5559-5564 ◽

Cited By ~ 59

Author(s):

Nicole R. Luke ◽

Joseph A. Jurcisek ◽

Lauren O. Bakaletz ◽

Anthony A. Campagnari

Keyword(s):

Moraxella Catarrhalis ◽

Biofilm Formation ◽

Infection Type ◽

Type Iv Pili ◽

In Vivo Studies ◽

Protein Subunit ◽

Human Respiratory Tract ◽

Nasopharyngeal Colonization ◽

Type Iv ◽

Wide Range

ABSTRACT Moraxella catarrhalis is a gram-negative mucosal pathogen of the human respiratory tract. Although little information is available regarding the initial steps of M. catarrhalis pathogenesis, this organism must be able to colonize the human mucosal surface in order to initiate an infection. Type IV pili (TFP), filamentous surface appendages primarily comprised of a single protein subunit termed pilin, play a crucial role in the initiation of disease by a wide range of bacteria. We previously identified the genes that encode the major proteins involved in the biosynthesis of M. catarrhalis TFP and determined that the TFP expressed by this organism are highly conserved and essential for natural transformation. We extended this initial study by investigating the contribution of TFP to the early stages of M. catarrhalis colonization. TFP-deficient M. catarrhalis bacteria exhibit diminished adherence to eukaryotic cells in vitro. Additionally, our studies demonstrate that M. catarrhalis cells form a mature biofilm in continuous-flow chambers and that biofilm formation is enhanced by TFP expression. The potential role of TFP in colonization by M. catarrhalis was further investigated using in vivo studies comparing the abilities of wild-type M. catarrhalis and an isogenic TFP mutant to colonize the nasopharynx of the chinchilla. These results suggest that the expression of TFP contributes to mucosal airway colonization. Furthermore, these data indicate that the chinchilla model of nasopharyngeal colonization provides an effective animal system for studying the early steps of M. catarrhalis pathogenesis.

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

10.1101/2021.10.21.465385 ◽

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.

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Imipenem Treatment Induces Expression of Important Genes and Phenotypes in a Resistant Acinetobacter baumannii Isolate

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01696-15 ◽

2015 ◽

Vol 60 (3) ◽

pp. 1370-1376 ◽

Cited By ~ 12

Author(s):

Ghulam Nasser Dhabaan ◽

Sazaly AbuBakar ◽

Gustavo Maia Cerqueira ◽

Mohammed Al-Haroni ◽

Sui Ping Pang ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Biofilm Formation ◽

Clinical Success ◽

Multidrug Resistant ◽

Type Iv Pili ◽

Control Measures ◽

Content Type ◽

Type Iv ◽

Abiotic Surfaces ◽

Colonization Factors

Acinetobacter baumanniihas emerged as a notorious multidrug-resistant pathogen, and development of novel control measures is of the utmost importance. Understanding the factors that play a role in drug resistance may contribute to the identification of novel therapeutic targets. Pili are essential forA. baumanniiadherence to and biofilm formation on abiotic surfaces as well as virulence. In the present study, we found that biofilm formation was significantly induced in an imipenem-resistant (Impr) strain treated with a subinhibitory concentration of antibiotic compared to that in an untreated control and an imipenem-susceptible (Imps) isolate. Using microarray and quantitative PCR analyses, we observed that several genes responsible for the synthesis of type IV pili were significantly upregulated in the Imprbut not in the Impsisolate. Notably, this finding is corroborated by an increase in the motility of the Imprstrain. Our results suggest that the ability to overproduce colonization factors in response to imipenem treatment confers biological advantage toA. baumanniiand may contribute to clinical success.

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