scholarly journals Mucin Promotes Rapid Surface Motility in Pseudomonas aeruginosa

mBio ◽  
2012 ◽  
Vol 3 (3) ◽  
Author(s):  
Amy T. Y. Yeung ◽  
Alicia Parayno ◽  
Robert E. W. Hancock
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iv Pili ◽  
Transcriptional Analysis ◽  
Bacterial Cells ◽  
Content Type ◽  
Type Iv ◽  
Sensing Systems ◽  
Bright Green ◽  
Surface Motility

ABSTRACTAn important environmental factor that determines the mode of motility adopted byPseudomonas aeruginosais the viscosity of the medium, often provided by adjusting agar concentrationsin vitro. However, the viscous gel-like property of the mucus layer that overlays epithelial surfaces is largely due to the glycoprotein mucin.P. aeruginosais known to swim within 0.3% (wt/vol) agar and swarm on the surface at 0.5% (wt/vol) agar with amino acids as a weak nitrogen source. When physiological concentrations or as little as 0.05% (wt/vol) mucin was added to the swimming agar, in addition to swimming,P. aeruginosawas observed to undergo highly accelerated motility on the surface of the agar. The surface motility colonies in the presence of mucin appeared to be circular, with a bright green center surrounded by a thicker white edge. While intact flagella were required for the surface motility in the presence of mucin, type IV pili and rhamnolipid production were not. Replacement of mucin with other wetting agents indicated that the lubricant properties of mucin might contribute to the surface motility. Based on studies with mutants, the quorum-sensing systems (lasandrhl) and the orphan autoinducer receptor QscR played important roles in this form of surface motility. Transcriptional analysis of cells taken from the motility zone revealed the upregulation of genes involved in virulence and resistance. Based on these results, we suggest that mucin may be promoting a new or highly modified form of surface motility, which we propose should be termed “surfing.”IMPORTANCEAn important factor that dictates the mode of motility adopted byP. aeruginosais the viscosity of the medium, often provided by adjusting agar concentrationsin vitro. However, the gel-like properties of the mucous layers that overlay epithelial surfaces, such as those of the lung, a major site ofPseudomonasinfection, are contributed mostly by the production of the glycoprotein mucin. In this study, we added mucin to swimming media and found that it promoted the ability ofP. aeruginosato exhibit rapid surface motility. These motility colonies appeared in a circular form, with a bright green center surrounded by a thicker white edge. Interestingly, bacterial cells at the thick edge appeared piled up and lacked flagella, while cells at the motility center had flagella. Our data from various genetic and phenotypic studies suggest that mucin may be promoting a modified form of swarming or a novel form of surface motility inP. aeruginosa.

scholarly journals The Swarming Motility of Pseudomonas aeruginosa Is Blocked by Cranberry Proanthocyanidins and Other Tannin-Containing Materials

2011 ◽  
Vol 77 (9) ◽  
pp. 3061-3067 ◽  
Author(s):  
Che O'May ◽  
Nathalie Tufenkji
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Adhesion ◽  
Type Iv Pili ◽  
Hydrolyzable Tannin ◽  
Swarming Motility ◽  
Subsequent Formation ◽  
Content Type ◽  
Type Iv ◽  
Derivatives Of ◽  
Growth Experiments

ABSTRACTBacterial motility plays a key role in the colonization of surfaces by bacteria and the subsequent formation of resistant communities of bacteria called biofilms. Derivatives of cranberry fruit, predominantly condensed tannins called proanthocyanidins (PACs) have been reported to interfere with bacterial adhesion, but the effects of PACs and other tannins on bacterial motilities remain largely unknown. In this study, we investigated whether cranberry PAC (CPAC) and the hydrolyzable tannin in pomegranate (PG; punicalagin) affected the levels of motilities exhibited by the bacteriumPseudomonas aeruginosa. This bacterium utilizes flagellum-mediated swimming motility to approach a surface, attaches, and then further spreads via the surface-associated motilities designated swarming and twitching, mediated by multiple flagella and type IV pili, respectively. Under the conditions tested, both CPAC and PG completely blocked swarming motility but did not block swimming or twitching motilities. Other cranberry-containing materials and extracts of green tea (also rich in tannins) were also able to block or impair swarming motility. Moreover, swarming bacteria were repelled by filter paper discs impregnated with many tannin-containing materials. Growth experiments demonstrated that the majority of these compounds did not impair bacterial growth. When CPAC- or PG-containing medium was supplemented with surfactant (rhamnolipid), swarming motility was partially restored, suggesting that the effective tannins are in part acting by a rhamnolipid-related mechanism. Further support for this theory was provided by demonstrating that the agar surrounding tannin-induced nonswarming bacteria was considerably less hydrophilic than the agar area surrounding swarming bacteria. This is the first study to show that natural compounds containing tannins are able to blockP. aeruginosaswarming motility and that swarming bacteria are repelled by such compounds.

scholarly journals Swarming of Pseudomonas aeruginosa Is Dependent on Cell-to-Cell Signaling and Requires Flagella and Pili

2000 ◽  
Vol 182 (21) ◽  
pp. 5990-5996 ◽  
Author(s):  
Thilo Köhler ◽  
Lasta Kocjancic Curty ◽  
Francisco Barja ◽  
Christian van Delden ◽  
Jean-Claude Pechère
Keyword(s):  
Amino Acids ◽  
Pseudomonas Aeruginosa ◽  
Cell Signaling ◽  
Light And Electron Microscopy ◽  
Sole Source ◽  
Type Iv Pili ◽  
Swarming Motility ◽  
Type Iv ◽  
Surface Motility ◽  
Swarming Behavior

ABSTRACT We describe swarming in Pseudomonas aeruginosa as a third mode of surface translocation in addition to the previously described swimming and twitching motilities. Swarming in P. aeruginosa is induced on semisolid surfaces (0.5 to 0.7% agar) under conditions of nitrogen limitation and in response to certain amino acids. Glutamate, aspartate, histidine, or proline, when provided as the sole source of nitrogen, induced swarming, while arginine, asparagine, and glutamine, among other amino acids, did not sustain swarming. Cells from the edge of the swarm were about twice as long as cells from the swarm center. In both instances, bacteria possessing two polar flagella were observed by light and electron microscopy. While afliC mutant of P. aeruginosa displayed slightly diminished swarming, a pilR and a pilA mutant, both deficient in type IV pili, were unable to swarm. Furthermore, cells with mutations in the las cell-to-cell signaling system showed diminished swarming behavior, while rhlmutants were completely unable to swarm. Evidence is presented for rhamnolipids being the actual surfactant involved in swarming motility, which explains the involvement of the cell-to-cell signaling circuitry of P. aeruginosa in this type of surface motility.

scholarly journals ThePseudomonas aeruginosaPilSR Two-Component System Regulates Both Twitching and Swimming Motilities

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Sara L. N. Kilmury ◽  
Lori L. Burrows
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iv Pili ◽  
Geobacter Sulfurreducens ◽  
Type Iv Pilus ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Swimming Motility ◽  
Type Iv ◽  
Two Component

ABSTRACTMotility is an important virulence trait for many bacterial pathogens, allowing them to position themselves in appropriate locations at appropriate times. The motility structures type IV pili and flagella are also involved in sensing surface contact, which modulates pathogenicity. InPseudomonas aeruginosa, the PilS-PilR two-component system (TCS) regulates expression of the type IV pilus (T4P) major subunit PilA, while biosynthesis of the single polar flagellum is regulated by a hierarchical system that includes the FleSR TCS. Previous studies ofGeobacter sulfurreducensandDichelobacter nodosusimplicated PilR in regulation of non-T4P-related genes, including some involved in flagellar biosynthesis. Here we used transcriptome sequencing (RNA-seq) analysis to identify genes in addition topilAwith changes in expression in the absence ofpilR. Among the genes identified were 10 genes whose transcription increased in thepilAmutant but decreased in thepilRmutant, despite both mutants lacking T4P and pilus-related phenotypes. The products of these inversely dysregulated genes, many of which were hypothetical, may be important for virulence and surface-associated behaviors, as mutants had altered swarming motility, biofilm formation, type VI secretion system expression, and pathogenicity in a nematode model. Further, the PilSR TCS positively regulated transcription offleSR, and thus many genes in the FleSR regulon. As a result,pilSRdeletion mutants had defects in swimming motility that were independent of the loss of PilA. Together, these data suggest that in addition to controlling T4P expression, PilSR could have a broader role in the regulation ofP. aeruginosamotility and surface sensing behaviors.IMPORTANCESurface appendages such as type IV pili and flagella are important for establishing surface attachment and infection in a host in response to appropriate cues. The PilSR regulatory system that controls type IV pilus expression inPseudomonas aeruginosahas an established role in expression of the major pilin PilA. Here we provide evidence supporting a new role for PilSR in regulating flagellum-dependent swimming motility in addition to pilus-dependent twitching motility. Further, even though bothpilAandpilRmutants lack PilA and pili, we identified sets of genes downregulated in thepilRmutant and upregulated in apilAmutant as well as genes downregulated only in apilRmutant, independent of pilus expression. This finding suggests that change in the inner membrane levels of PilA is only one of the cues to which PilR responds to modulate gene expression. Identification of PilR as a regulator of multiple motility pathways may make it an interesting therapeutic target for antivirulence compounds.

scholarly journals Determination of the Dynamically Linked Indices of Fosfomycin for Pseudomonas aeruginosa in the Hollow Fiber Infection Model

2018 ◽  
Vol 62 (6) ◽  
Author(s):  
Arnold Louie ◽  
Michael Maynard ◽  
Brandon Duncanson ◽  
Jocelyn Nole ◽  
Michael Vicchiarelli ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Hollow Fiber ◽  
The United States ◽  
Infection Model ◽  
Combination Regimen ◽  
Bacterial Cells ◽  
Time Curve ◽  
Minimum Concentration ◽  
Content Type

ABSTRACT Fosfomycin is the only expoxide antimicrobial and is currently under development in the United States as an intravenously administered product. We were interested in identifying the exposure indices most closely linked to its ability to kill bacterial cells and to suppress amplification of less susceptible subpopulations. We employed the hollow fiber infection model for this investigation and studied wild-type strain Pseudomonas aeruginosa PAO1. Because of anticipated rapid resistance emergence, we shortened the study duration to 24 h but sampled the system more intensively. Doses of 12 and 18 g/day and schedules of daily administration, administration every 8 h, and administration by continuous infusion for each daily dose were studied. We measured fosfomycin concentrations (by liquid chromatography-tandem mass spectrometry), the total bacterial burden, and the burden of less susceptible isolates. We applied a mathematical model to all the data simultaneously. There was a rapid emergence of resistance with all doses and schedules. Prior to resistance emergence, an initial kill of 2 to 3 log 10 (CFU/ml) was observed. The model demonstrated that the area under the concentration-time curve/MIC ratio was linked to total bacterial kill, while the time that the concentration remained above the MIC (or, equivalently, the minimum concentration/MIC ratio) was linked to resistance suppression. These findings were also seen in other investigations with Enterobacteriaceae ( in vitro systems) and P. aeruginosa (murine system). We conclude that for serious infections with high bacterial burdens, fosfomycin may be of value as a new therapeutic and may be optimized by administering the agent as a continuous or prolonged infusion or by use of a short dosing interval. For indications such as ventilator-associated bacterial pneumonia, it may be prudent to administer fosfomycin as part of a combination regimen.

scholarly journals Laboratory and clinical Pseudomonas aeruginosa strains do not bind glycosphingolipids in vitro or during type IV pili-mediated initial host cell attachment

Microbiology ◽  
2006 ◽  
Vol 152 (9) ◽  
pp. 2789-2799 ◽  
Author(s):  
Aufaugh Emam ◽  
Analyn R. Yu ◽  
Hyun-Joo Park ◽  
Radhia Mahfoud ◽  
Julianne Kus ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Epithelial Cell ◽  
Cell Attachment ◽  
Positive Control ◽  
Type Iv Pili ◽  
Lung Epithelial Cells ◽  
Target Cells ◽  
Type Iv ◽  
Host Cell Attachment

The glycosphingolipids (GSLs) gangliotriaosylceramide (Gg3) and gangliotetraosylceramide (Gg4) have been implicated as receptors for type IV pili (T4P)-mediated Pseudomonas aeruginosa epithelial cell attachment. Since P. aeruginosa T4P are divided into five groups, the authors determined whether GSLs in general, and Gg3 and Gg4 in particular, are specifically bound and required for host epithelial cell attachment of clinical and laboratory strains within these groups. An enterohaemorrhagic Escherichia coli strain, CL56, known to bind to both Gg3 and Gg4, provided a positive control. TLC overlay showed no binding of more than 12 P. aeruginosa strains to either Gg3 or Gg4 (or other GSLs), while CL56 Gg3/Gg4 binding was readily detectable. GSL ELISA similarly demonstrated no significant P. aeruginosa binding to Gg3 or Gg4, compared with CL56. Using a selective chemical inhibitor, epithelial cell GSL synthesis was abrogated, and Gg3 and Gg4 expression deleted, but P. aeruginosa attachment was not impaired. Target cell attachment was mediated by T4P, since non-piliated, but flagellated, mutants were unable to bind to the target cells. CFTR (cystic fibrosis transmembrane conductance regulator) has also been implicated as a receptor; however, in this work, overexpression of CFTR had no effect on P. aeruginosa binding. It is concluded that neither Gg3 nor Gg4 are specifically recognized by P. aeruginosa, and that endogenous GSLs do not have a role in the attachment of live intact P. aeruginosa to cultured lung epithelial cells. In contrast to whole piliated P. aeruginosa, T4P sheared from such bacteria showed significant Gg3 and Gg4 binding, which may explain the results of other studies.

scholarly journals Regulation of Type IV Pili Contributes to Surface Behaviors of Historical and Epidemic Strains of Clostridium difficile

2015 ◽  
Vol 198 (3) ◽  
pp. 565-577 ◽  
Author(s):  
Erin B. Purcell ◽  
Robert W. McKee ◽  
Eric Bordeleau ◽  
Vincent Burrus ◽  
Rita Tamayo
Keyword(s):  
Clostridium Difficile ◽  
Biofilm Formation ◽  
The United States ◽  
Type Iv Pili ◽  
Flagellar Motility ◽  
Content Type ◽  
Type Iv ◽  
Intestinal Pathogen ◽  
Surface Motility ◽  
Pilin Gene

ABSTRACTThe intestinal pathogenClostridium difficileis an urgent public health threat that causes antibiotic-associated diarrhea and is a leading cause of fatal nosocomial infections in the United States.C. difficilerates of recurrence and mortality have increased in recent years due to the emergence of so-called “hypervirulent” epidemic strains. A great deal of the basic biology ofC. difficilehas not been characterized. Recent findings that flagellar motility, toxin synthesis, and type IV pilus (TFP) formation are regulated by cyclic diguanylate (c-di-GMP) reveal the importance of this second messenger forC. difficilegene regulation. However, the function(s) of TFP inC. difficileremains largely unknown. Here, we examine TFP-dependent phenotypes and the role of c-di-GMP in controlling TFP production in the historical 630 and epidemic R20291 strains ofC. difficile. We demonstrate that TFP contribute toC. difficilebiofilm formation in both strains, but with a more prominent role in R20291. Moreover, we report that R20291 is capable of TFP-dependent surface motility, which has not previously been described inC. difficile. The expression and regulation of thepilA1pilin gene differs between R20291 and 630, which may underlie the observed differences in TFP-mediated phenotypes. The differences inpilA1expression are attributable to greater promoter-driven transcription in R20291. In addition, R20291, but not 630, upregulates c-di-GMP levels during surface-associated growth, suggesting that the bacterium senses its substratum. The differential regulation of surface behaviors in historical and epidemicC. difficilestrains may contribute to the different infection outcomes presented by these strains.IMPORTANCEHowClostridium difficileestablishes and maintains colonization of the host bowel is poorly understood. Surface behaviors ofC. difficileare likely relevant during infection, representing possible interactions between the bacterium and the intestinal environment. Pili mediate bacterial interactions with various surfaces and contribute to the virulence of many pathogens. We report that type IV pili (TFP) contribute to biofilm formation byC. difficile. TFP are also required for surface motility, which has not previously been demonstrated forC. difficile. Furthermore, an epidemic-associatedC. difficilestrain showed higher pilin gene expression and greater dependence on TFP for biofilm production and surface motility. Differences in TFP regulation and their effects on surface behaviors may contribute to increased virulence in recent epidemic strains.

scholarly journals Novel Role for PilNO in Type IV Pilus Retraction Revealed by Alignment Subcomplex Mutations

2015 ◽  
Vol 197 (13) ◽  
pp. 2229-2238 ◽  
Author(s):  
Tiffany L. Leighton ◽  
Neha Dayalani ◽  
Liliana M. Sampaleanu ◽  
P. Lynne Howell ◽  
Lori L. Burrows
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Small Molecule ◽  
Small Molecule Inhibitors ◽  
Type Iv Pili ◽  
Site Directed Mutagenesis ◽  
Twitching Motility ◽  
Content Type ◽  
The Core ◽  
Type Iv ◽  
Two Hybrid

ABSTRACTType IV pili (T4P) are dynamic protein filaments that mediate bacterial adhesion, biofilm formation, and twitching motility. The highly conserved PilMNOP proteins form an inner membrane alignment subcomplex required for function of the T4P system, though their exact roles are unclear. Three potential interaction interfaces for PilNO were identified: core-core, coiled coils (CC), and the transmembrane segments (TMSs). A high-confidence PilNO heterodimer model was used to select key residues for mutation, and the resulting effects on protein-protein interactions were examined both in a bacterial two-hybrid (BTH) system and in their nativePseudomonas aeruginosacontext. Mutations in the oppositely charged CC regions or the TMS disrupted PilNO heterodimer formation in the BTH assay, while up to six combined mutations in the core failed to disrupt the interaction. When the mutations were introduced into theP. aeruginosachromosome at thepilNorpilOlocus, specific changes at each of the three interfaces—including core mutations that failed to disrupt interactions in the BTH system—abrogated surface piliation and/or impaired twitching motility. Unexpectedly, specific CC mutants were hyperpiliated but nonmotile, a hallmark of pilus retraction defects. These data suggest that PilNO participate in both the extension and retraction of T4P. Our findings support a model of multiple, precise interaction interfaces between PilNO; emphasize the importance of studying protein function in a minimally perturbed context and stoichiometry; and highlight potential target sites for development of small-molecule inhibitors of the T4P system.IMPORTANCEPseudomonas aeruginosais an opportunistic pathogen that uses type IV pili (T4P) for host attachment. The T4P machinery is composed of four cell envelope-spanning subcomplexes. PilN and PilO heterodimers are part of the alignment subcomplex and essential for T4P function. Three potential PilNO interaction interfaces (the core-core, coiled-coil, and transmembrane segment interfaces) were probed using site-directed mutagenesis followed by functional assays in anEscherichia colitwo-hybrid system and inP. aeruginosa. Several mutations blocked T4P assembly and/or motility, including two that revealed a novel role for PilNO in pilus retraction, while other mutations affected extension dynamics. These critical PilNO interaction interfaces represent novel targets for small-molecule inhibitors with the potential to disrupt T4P function.

scholarly journals Potency of Vaborbactam Is Less Affected than That of Avibactam in Strains Producing KPC-2 Mutations That Confer Resistance to Ceftazidime-Avibactam

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Ruslan Tsivkovski ◽  
Olga Lomovskaya
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Inhibitory Concentration ◽  
Fold Increase ◽  
Clinical Settings ◽  
Bacterial Cells ◽  
Wild Type ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Lactamase Inhibitor

ABSTRACT Resistance to ceftazidime-avibactam due to mutations in KPC genes has been reported both in vitro and in clinical settings. The most frequently reported mutation leads to the amino acid substitution D179Y in the Ω loop of the enzyme. Bacterial cells that carry mutant KPC acquire a higher level of ceftazidime resistance, become more sensitive to other cephalosporins, and almost completely lose resistance to carbapenems. In this study, we demonstrated that two substitutions in KPC-2, D179Y and L169P, reduce the ability of avibactam to enhance the activity of ceftazidime, cefepime, or piperacillin against isogenic efflux-deficient strains of Pseudomonas aeruginosa, 8- to 32-fold and 4- to 16-fold for the D179Y and L169P variants, respectively, depending on the antibiotic. In contrast, the potency of vaborbactam, the structurally unrelated β-lactamase inhibitor that was recently approved by the FDA in combination with meropenem, is reduced no more than 2-fold. Experiments with purified enzymes demonstrate that the D179Y substitution causes an ∼20-fold increase in the 50% inhibitory concentration (IC50) for inhibition of ceftazidime hydrolysis by avibactam, versus 2-fold for vaborbactam, and that the L169P substitution has an ∼4.5-fold-stronger effect on the affinity for avibactam than for vaborbactam. In addition, the D179Y and L169P variants hydrolyze ceftazidime with 10-fold and 4-fold-higher efficiencies, respectively, than that of wild-type KPC-2. Thus, microbiological and biochemical experiments implicate both decreased ability of avibactam to interact with KPC-2 variants and an increase in the efficiency of ceftazidime hydrolysis in resistance to ceftazidime-avibactam. These substitutions have a considerably lesser effect on interactions with vaborbactam, making the meropenem-vaborbactam combination a valuable agent in managing infections due to KPC-producing carbapenem-resistant Enterobacteriaceae.

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 Role of Cyclic Di-GMP and Exopolysaccharide in Type IV Pilus Dynamics

2017 ◽  
Vol 199 (8) ◽  
Author(s):  
Jan Ribbe ◽  
Amy E. Baker ◽  
Sebastian Euler ◽  
George A. O'Toole ◽  
Berenike Maier
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Molecular Motor ◽  
Type Iv Pili ◽  
Force Generation ◽  
Surface Attachment ◽  
Content Type ◽  
Type Iv ◽  
Critical Components ◽  
Planktonic State

ABSTRACT For Pseudomonas aeruginosa, levels of cyclic di-GMP (c-di-GMP) govern the transition from the planktonic state to biofilm formation. Type IV pili (T4P) are crucial determinants of biofilm structure and dynamics, but it is unknown how levels of c-di-GMP affect pilus dynamics. Here, we scrutinized how c-di-GMP affects molecular motor properties and adhesive behavior of T4P. By means of retraction, T4P generated forces of ∼30 pN. Deletion mutants in the proteins with known roles in biofilm formation, swarming motility, and exopolysaccharide (EPS) production (specifically, the diguanylate cyclases sadC and roeA or the c-di-GMP phosphodiesterase bifA) showed only modest effects on velocity or force of T4P retraction. At high levels of c-di-GMP, the production of exopolysaccharides, particularly of Pel, is upregulated. We found that Pel production strongly enhances T4P-mediated surface adhesion of P. aeruginosa, suggesting that T4P-matrix interactions may be involved in biofilm formation by P. aeruginosa. Finally, our data support the previously proposed model of slingshot-like “twitching” motility of P. aeruginosa. IMPORTANCE Type IV pili (T4P) play various important roles in the transition of bacteria from the planktonic state to the biofilm state, including surface attachment and surface sensing. Here, we investigate adhesion, dynamics, and force generation of T4P after bacteria engage a surface. Our studies showed that two critical components of biofilm formation by Pseudomonas aeruginosa, T4P and exopolysaccharides, contribute to enhanced T4P-mediated force generation by attached bacteria. These data indicate a crucial role for the coordinated impact of multiple biofilm-promoting factors during the early stages of attachment to a surface. Our data are also consistent with a previous model explaining why pilus-mediated motility in P. aeruginosa results in characteristic “twitching” behavior.

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