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

2007 ◽  
Vol 75 (12) ◽  
pp. 5559-5564 ◽  
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.

scholarly journals Expression of Type IV Pili by Moraxella catarrhalis Is Essential for Natural Competence and Is Affected by Iron Limitation

2004 ◽  
Vol 72 (11) ◽  
pp. 6262-6270 ◽  
Author(s):  
Nicole R. Luke ◽  
Amy J. Howlett ◽  
Jianqiang Shao ◽  
Anthony A. Campagnari
Keyword(s):  
Moraxella Catarrhalis ◽  
Pathogenic Bacteria ◽  
Type Iv Pili ◽  
Protein Subunit ◽  
Electron Microscopic ◽  
Type Iv ◽  
Wide Range ◽  
Genes Encoding ◽  
Microscopic Studies

ABSTRACT Type IV pili, filamentous surface appendages primarily composed of a single protein subunit termed pilin, play a crucial role in the initiation of disease by a wide range of pathogenic bacteria. Although previous electron microscopic studies suggested that pili might be present on the surface of Moraxella catarrhalis isolates, detailed molecular and phenotypic analyses of these structures have not been reported to date. We identified and cloned the M. catarrhalis genes encoding PilA, the major pilin subunit, PilQ, the outer membrane secretin through which the pilus filament is extruded, and PilT, the NTPase that mediates pilin disassembly and retraction. To initiate investigation of the role of this surface organelle in pathogenesis, isogenic pilA, pilT, and pilQ mutants were constructed in M. catarrhalis strain 7169. Comparative analyses of the wild-type 7169 strain and three isogenic pil mutants demonstrated that M. catarrhalis expresses type IV pili that are essential for natural genetic transformation. Our studies suggest type IV pilus production by M. catarrhalis is constitutive and ubiquitous, although pilin expression was demonstrated to be iron responsive and Fur regulated. These data indicate that additional studies aimed at elucidating the prevalence and role of type IV pili in the pathogenesis and host response to M. catarrhalis infections are warranted.

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 Axenic Biofilm Formation and Aggregation bySynechocystissp. Strain PCC 6803 Are Induced by Changes in Nutrient Concentration and Require Cell Surface Structures

2019 ◽  
Vol 85 (7) ◽  
Author(s):  
Rey Allen ◽  
Bruce E. Rittmann ◽  
Roy Curtiss
Keyword(s):  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Type Iv Pili ◽  
Biofuel Production ◽  
Oxygenic Photosynthesis ◽  
Phototrophic Biofilm ◽  
Bg11 Medium ◽  
Phototrophic Biofilms ◽  
Type Iv ◽  
Cell Surface Structures

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.

scholarly journals Type IV pili promote early biofilm formation byClostridium difficile

2016 ◽  
Vol 74 (6) ◽  
pp. ftw061 ◽  
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

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

2005 ◽  
Vol 187 (4) ◽  
pp. 1455-1464 ◽  
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.

scholarly journals Archaeal type IV pili and their involvement in biofilm formation

2015 ◽  
Vol 06 ◽  
Author(s):  
Mechthild Pohlschroder ◽  
Rianne N. Esquivel
Keyword(s):  
Biofilm Formation ◽  
Type Iv Pili ◽  
Type Iv

scholarly journals Pseudomonas aeruginosatype IV minor pilins and PilY1 regulate virulence by modulating FimS-AlgR activity

2017 ◽  
Author(s):  
Victoria A. Marko ◽  
Sara L.N. Kilmury ◽  
Lesley T. MacNeil ◽  
Lori L. Burrows
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Feedback Inhibition ◽  
Regulatory System ◽  
Type Iv Pili ◽  
Infection Model ◽  
Type Iv ◽  
Wide Range ◽  
Lung Infections ◽  
Pilus Assembly

AbstractType IV pili are expressed by a wide range of prokaryotes, including the opportunistic pathogenPseudomonas aeruginosa. These flexible fibres mediate twitching motility, biofilm maturation, surface adhesion, and virulence. The pilus is composed mainly of major pilin subunits while the low abundance minor pilins FimU-PilVWXE and the putative adhesin PilY1 prime pilus assembly and are proposed to form the pilus tip. The minor pilins and PilY1 are encoded in an operon that is positively regulated by the FimS-AlgR two-component system. Independent of pilus assembly, PilY1 is proposed to be a mechanosensory component that - in conjunction with minor pilins - triggers up-regulation of acute virulence phenotypes upon surface attachment. Here, we investigated the link between the minor pilins and virulence.pilW, pilX, andpilY1mutants had reduced virulence towardsCaenorhabditis elegansrelative to wild type or a major pilin mutant, implying a role in pathogenicity that is independent of pilus assembly. We hypothesized that loss of specific minor pilins relieves feedback inhibition on FimS-AlgR, increasing transcription of the minor pilin operon and other members of the AlgR regulon. Reporter assays confirmed that FimS-AlgR were required for the increased expression from the minor pilin operon promoter upon loss of select minor pilins. Overexpression of AlgR or its hyperactivation via point mutation reduced virulence, and the virulence defects ofpilW,pilX, andpilY1mutants were dependent on FimS-AlgR expression and activation. We propose that PilY1 and the minor pilins inhibit their own expression, and that loss of these proteins leads to FimS-mediated activation of AlgR and reduced expression of acute-phase virulence factors. This mechanism could contribute to adaptation ofP. aeruginosain chronic lung infections, as mutations in the minor pilin operon result in the loss of piliation and increased expression of AlgR-dependent virulence factors – such as alginate – that are characteristic of such infections.Author summaryPseudomonas aeruginosacauses dangerous infections, including chronic lung infections in cystic fibrosis patients. It uses many strategies to infect its hosts, including deployment of grappling hook-like fibres called type IV pili. Among the components involved in assembly and function of the pilus are five proteins called minor pilins that - along with a larger protein called PilY1 - may help the pilus attach to surfaces. In a roundworm infection model, loss of PilY1 and specific minor pilins delayed killing, while loss of other pilus proteins did not. We traced this effect to increased activation of the FimS-AlgR regulatory system that inhibits expression of virulence factors used to initiate infections, while positively regulating chronic infection traits such as alginate production, a phenotype called mucoidy. A disruption in the appropriate timing of FimS-AlgR-dependent virulence factor expression when select minor pilins or PilY1 are missing may explain why those pilus-deficient mutants have reduced virulence compared with others whose products are not under FimS-AlgR control. Increased FimS-AlgR activity upon loss of PilY1 and specific minor pilins could help to explain the frequent co-occurrence of the non-piliated and mucoid phenotypes that are hallmarks of chronicP. aeruginosalung infections.

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 Two type IV pili ofVibrio parahaemolyticusplay different roles in biofilm formation

2006 ◽  
Vol 264 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Akiko Shime-Hattori ◽  
Tetsuya Iida ◽  
Michiko Arita ◽  
Kwon-Sam Park ◽  
Toshio Kodama ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Type Iv Pili ◽  
Type Iv
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