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Articles 31 - 60 of 76
Full-Text Articles in Medical Microbiology
Gene Deletion By Fluorescence-Reported Allelic Exchange Mutagenesis In Chlamydia Trachomatis, Konrad E. Mueller, Katerina Wolf, Kenneth A. Fields
Gene Deletion By Fluorescence-Reported Allelic Exchange Mutagenesis In Chlamydia Trachomatis, Konrad E. Mueller, Katerina Wolf, Kenneth A. Fields
Microbiology, Immunology, and Molecular Genetics Faculty Publications
Although progress in Chlamydia genetics has been rapid, genomic modification has previously been limited to point mutations and group II intron insertions which truncate protein products. The bacterium has thus far been intractable to gene deletion or more-complex genomic integrations such as allelic exchange. Herein, we present a novel suicide vector dependent on inducible expression of a chlamydial gene that renders Chlamydia trachomatis fully genetically tractable and permits rapid reverse genetics by fluorescence-reported allelic exchange mutagenesis (FRAEM). We describe the first available system of targeting chlamydial genes for deletion or allelic exchange as well as curing plasmids from C. trachomatis …
Application Of Β-Lactamase Reporter Fusions As An Indicator Of Effector Protein Secretion During Infections With The Obligate Intracellular Pathogen Chlamydia Trachomatis , Konrad E. Mueller, Kenneth A. Fields
Application Of Β-Lactamase Reporter Fusions As An Indicator Of Effector Protein Secretion During Infections With The Obligate Intracellular Pathogen Chlamydia Trachomatis , Konrad E. Mueller, Kenneth A. Fields
Microbiology, Immunology, and Molecular Genetics Faculty Publications
Chlamydia spp. utilize multiple secretion systems, including the type III secretion system (T3SS), to deploy host-interactive effector proteins into infected host cells. Elucidation of secreted proteins has traditionally required ectopic expression in a surrogate T3SS followed by immunolocalization of endogenous candidate effectors to confirm secretion by chlamydiae. The ability to transform Chlamydia and achieve stable expression of recombinant gene products has enabled a more direct assessment of secretion. We adapted TEM-1 β-lactamase as a reporter system for assessment of chlamydial protein secretion. We provide evidence that this system facilitates visualization of secretion in the context of infection. Specifically, our findings …
Antibacterial Evaluation Of Polygonum Multiflorum, Andy S. Demianicz
Antibacterial Evaluation Of Polygonum Multiflorum, Andy S. Demianicz
Seton Hall University Dissertations and Theses (ETDs)
Polygonum multiflorum, commonly known as Chinese Knotweed, is a tonic herb primarily used to enhance bodily functions. Recently, it has been shown to contain strong antioxidant, antibacterial and antiviral activity. The extract from the roots of Chinese Knotweed was used to assess its antibacterial properties against a broad spectrum of bacterial species, including 5 Gram-positive (B. cereus, B. megaterium, S. epidermidis, S. mutans and S. pyogenes) and 4 Gram-negative (E. aerogenes, E. coli, P. vulgaris and P. aeruginosa). Microtiter assays were carried out to evaluate the antibacterial activity of Chinese Knotweed at 0.5%, 1%, 1.5% and 2.5% concentrations in order …
The Crispr/Cas Adaptive Immune System Of Pseudomonas Aeruginosa Mediates Resistance To Naturally Occurring And Engineered Phages, Kyle C. Cady, Joe Bondy-Denomy, Gary E. Heussler, Alan R. Davidson, George A. O'Toole
The Crispr/Cas Adaptive Immune System Of Pseudomonas Aeruginosa Mediates Resistance To Naturally Occurring And Engineered Phages, Kyle C. Cady, Joe Bondy-Denomy, Gary E. Heussler, Alan R. Davidson, George A. O'Toole
Dartmouth Scholarship
Here we report the isolation of 6 temperate bacteriophages (phages) that are prevented from replicating within the laboratory strain Pseudomonas aeruginosa PA14 by the endogenous CRISPR/Cas system of this microbe. These phages are only the second identified group of naturally occurring phages demonstrated to be blocked for replication by a nonengineered CRISPR/Cas system, and our results provide the first evidence that the P. aeruginosa type I-F CRISPR/Cas system can function in phage resistance. Previous studies have highlighted the importance of the protospacer adjacent motif (PAM) and a proximal 8-nucleotide seed sequence in mediating CRISPR/Cas-based immunity. Through engineering of a protospacer …
Prevalence Of Streptococci And Increased Polymicrobial Diversity Associated With Cystic Fibrosis Patient Stability, L. M. Filkins, T. H. Hampton, A. H. Gifford, M. J. Gross, D. A. Hogan, M. L. Sogin, H. G. Morrison, B. J. Paster, G. A. O'Toole
Prevalence Of Streptococci And Increased Polymicrobial Diversity Associated With Cystic Fibrosis Patient Stability, L. M. Filkins, T. H. Hampton, A. H. Gifford, M. J. Gross, D. A. Hogan, M. L. Sogin, H. G. Morrison, B. J. Paster, G. A. O'Toole
Dartmouth Scholarship
Diverse microbial communities chronically colonize the lungs of cystic fibrosis patients. Pyrosequencing of amplicons for hypervariable regions in the 16S rRNA gene generated taxonomic profiles of bacterial communities for sputum genomic DNA samples from 22 patients during a state of clinical stability (outpatients) and 13 patients during acute exacerbation (inpatients). We employed quantitative PCR (qPCR) to confirm the detection of Pseudomonas aeruginosa and Streptococcus by the pyrosequencing data and human oral microbe identification microarray (HOMIM) analysis to determine the species of the streptococci identified by pyrosequencing. We show that outpatient sputum samples have significantly higher bacterial diversity than inpatients, but …
Lapg, Required For Modulating Biofilm Formation By Pseudomonas Fluorescens Pf0-1, Is A Calcium-Dependent Protease, Chelsea D. Boyd, Debashree Chatterjee, Holger Sondermann, George A. O'Toole
Lapg, Required For Modulating Biofilm Formation By Pseudomonas Fluorescens Pf0-1, Is A Calcium-Dependent Protease, Chelsea D. Boyd, Debashree Chatterjee, Holger Sondermann, George A. O'Toole
Dartmouth Scholarship
Biofilm formation by Pseudomonas fluorescens Pf0-1 requires the cell surface adhesin LapA. We previously reported that LapG, a periplasmic cysteine protease of P. fluorescens, cleaves the N terminus of LapA, thus releasing this adhesin from the cell surface and resulting in loss of the ability to make a biofilm. The activity of LapG is regulated by the inner membrane-localized cyclic-di-GMP receptor LapD via direct protein-protein interactions. Here we present chelation and metal add-back studies demonstrating that calcium availability regulates biofilm formation by P. fluorescens Pf0-1. The determination that LapG is a calcium-dependent protease, based on in vivo and in vitro …
Structural Characterization Of A Conserved, Calcium-Dependent Periplasmic Protease From Legionella Pneumophila, Debashree Chatterjee, Chelsea D. Boyd, George A. O'Toole, Holger Sondermann
Structural Characterization Of A Conserved, Calcium-Dependent Periplasmic Protease From Legionella Pneumophila, Debashree Chatterjee, Chelsea D. Boyd, George A. O'Toole, Holger Sondermann
Dartmouth Scholarship
The bacterial dinucleotide second messenger c-di-GMP has emerged as a central molecule in regulating bacterial behavior, including motility and biofilm formation. Proteins for the synthesis and degradation of c-di-GMP and effectors for its signal transmission are widely used in the bacterial domain. Previous work established the GGDEF-EAL domain-containing receptor LapD as a central switch in Pseudomonas fluorescens cell adhesion. LapD senses c-di-GMP inside the cytosol and relays this signal to the outside by the differential recruitment of the periplasmic protease LapG. Here we identify the core components of an orthologous system in Legionella pneumophila. Despite only moderate sequence conservation at …
2-Heptyl-4-Quinolone, A Precursor Of The Pseudomonas Quinolone Signal Molecule, Modulates Swarming Motility In Pseudomonas Aeruginosa, Dae-Gon Ha, Judith H. Merritt, Thomas H. Hampton, James T. Hodgkinson, Matej Janecek, David R. Spring, Martin Welch, George A. O'Toole
2-Heptyl-4-Quinolone, A Precursor Of The Pseudomonas Quinolone Signal Molecule, Modulates Swarming Motility In Pseudomonas Aeruginosa, Dae-Gon Ha, Judith H. Merritt, Thomas H. Hampton, James T. Hodgkinson, Matej Janecek, David R. Spring, Martin Welch, George A. O'Toole
Dartmouth Scholarship
Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors, including biofilm formation and swarming motility. These group behaviors are regulated by both the intracellular signaling molecule c-di-GMP and acylhomoserine lactone quorum-sensing systems. Here, we show that the Pseudomonas quinolone signal (PQS) system also contributes to the regulation of swarming motility. Specifically, our data indicate that 2-heptyl-4-quinolone (HHQ), a precursor of PQS, likely induces the production of the phenazine-1-carboxylic acid (PCA), which in turn acts via an as-yet-unknown downstream mechanism to repress swarming motility. We show that this HHQ- and PCA-dependent swarming repression is apparently independent of changes in global …
Characterization Of Vibrio Cholerae O1 El Tor Biotype Variant Clinical Isolates From Bangladesh And Haiti, Including A Molecular Genetic Analysis Of Virulence Genes, Mike S. Son, Christina J. Megli, Gabriela Kovacikova, Firdausi Qadri, Ronald K. Taylor
Characterization Of Vibrio Cholerae O1 El Tor Biotype Variant Clinical Isolates From Bangladesh And Haiti, Including A Molecular Genetic Analysis Of Virulence Genes, Mike S. Son, Christina J. Megli, Gabriela Kovacikova, Firdausi Qadri, Ronald K. Taylor
Dartmouth Scholarship
Vibrio cholerae serogroup O1, the causative agent of the diarrheal disease cholera, is divided into two biotypes: classical and El Tor. Both biotypes produce the major virulence factors toxin-coregulated pilus (TCP) and cholera toxin (CT). Although possessing genotypic and phenotypic differences, El Tor biotype strains displaying classical biotype traits have been reported and subsequently were dubbed El Tor variants. Of particular interest are reports of El Tor variants that produce various levels of CT, including levels typical of classical biotype strains. Here, we report the characterization of 10 clinical isolates from the International Centre for Diarrhoeal Disease Research, Bangladesh, and …
Protection And Attachment Of Vibrio Cholerae Mediated By The Toxin-Coregulated Pilus In The Infant Mouse Model, Shelly J. Krebs, Ronald K. Taylor
Protection And Attachment Of Vibrio Cholerae Mediated By The Toxin-Coregulated Pilus In The Infant Mouse Model, Shelly J. Krebs, Ronald K. Taylor
Dartmouth Scholarship
Colonization of the human small intestine by Vibrio cholerae is an essential step in pathogenesis that requires the type IV toxin-coregulated pilus (TCP). To date, three functions of TCP have been characterized: it serves as the CTXΦ receptor, secretes the colonization factor TcpF, and functions in microcolony formation by mediating bacterium-bacterium interactions. Although type IV pili in other pathogenic bacteria have been characterized as playing a major role in attachment to epithelial cells, there are very few studies to suggest that TCP acts as an attachment factor. Taking this into consideration, we investigated the function of TCP in attachment to …
Roles Of Three Transporters, Cbcxwv, Bett1, And Bett3, In Pseudomonas Aeruginosa Choline Uptake For Catabolism, Adel A. Malek, Chiliang Chen, Matthew J. Wargo, Gwyn A. Beattie, Deborah A. Hogan
Roles Of Three Transporters, Cbcxwv, Bett1, And Bett3, In Pseudomonas Aeruginosa Choline Uptake For Catabolism, Adel A. Malek, Chiliang Chen, Matthew J. Wargo, Gwyn A. Beattie, Deborah A. Hogan
Dartmouth Scholarship
Pseudomonas aeruginosa uses the quaternary amine choline as a carbon source, osmoprotectant, and macromolecular precursor. The importance of choline in P. aeruginosa physiology is highlighted by the presence of multiple known and putative choline transporters encoded within its genome. This report describes the relative roles of three choline transporters, the ABC transporter CbcXWV and two symporters, BetT1 and BetT3, in P. aeruginosa growth on choline under osmotic conditions that are physiologically relevant to eukaryotic hosts. The increased lag phases exhibited by the ΔbetT1 and ΔbetT1 ΔbetT3 mutants relative to the wild type upon transfer to medium with …
Whole-Genome Sequencing Of Staphylococcus Aureus Strain Rn4220, A Key Laboratory Strain Used In Virulence Research, Identifies Mutations That Affect Not Only Virulence Factors But Also The Fitness Of The Strain, Dhanalakshmi Nair, Guido Memmi, David Hernandez, Jonathan Bard, Marie Beaume, Steven Gill, Patrice Francois, Ambrose L. Cheung
Whole-Genome Sequencing Of Staphylococcus Aureus Strain Rn4220, A Key Laboratory Strain Used In Virulence Research, Identifies Mutations That Affect Not Only Virulence Factors But Also The Fitness Of The Strain, Dhanalakshmi Nair, Guido Memmi, David Hernandez, Jonathan Bard, Marie Beaume, Steven Gill, Patrice Francois, Ambrose L. Cheung
Dartmouth Scholarship
Staphylococcus aureus RN4220, a cloning intermediate, is sometimes used in virulence, resistance, and metabolic studies. Using whole-genome sequencing, we showed that RN4220 differs from NCTC8325 and contains a number of genetic polymorphisms that affect both virulence and general fitness, implying a need for caution in using this strain for such studies.
The Pseudomonas Aeruginosa Magnesium Transporter Mgte Inhibits Transcription Of The Type Iii Secretion System, Gregory G. Anderson, Timothy L. Yahr, Rustin R. Lovewell, George A. O'Toole
The Pseudomonas Aeruginosa Magnesium Transporter Mgte Inhibits Transcription Of The Type Iii Secretion System, Gregory G. Anderson, Timothy L. Yahr, Rustin R. Lovewell, George A. O'Toole
Dartmouth Scholarship
Pseudomonas aeruginosa is an opportunistic pathogen that causes life-long pneumonia in individuals with cystic fibrosis (CF). These long-term infections are maintained by bacterial biofilm formation in the CF lung. We have recently developed a model of P. aeruginosa biofilm formation on cultured CF airway epithelial cells. Using this model, we discovered that mutation of a putative magnesium transporter gene, called mgtE, led to increased cytotoxicity of P. aeruginosa toward epithelial cells. This altered toxicity appeared to be dependent upon expression of the type III secretion system (T3SS). In this study, we found that mutation of mgtE results in increased T3SS …
Salicylic Acid Diminishes Staphylococcus Aureus Capsular Polysaccharide Type 5 Expression, Lucia P. Alvarez, Maria S. Barbagelata, Mariana Gordiola, A. L. Cheung
Salicylic Acid Diminishes Staphylococcus Aureus Capsular Polysaccharide Type 5 Expression, Lucia P. Alvarez, Maria S. Barbagelata, Mariana Gordiola, A. L. Cheung
Dartmouth Scholarship
Capsular polysaccharides (CP) of serotypes 5 (CP5) and 8 (CP8) are major Staphylococcus aureus virulence factors. Previous studies have shown that salicylic acid (SAL), the main aspirin metabolite, affects the expression of certain bacterial virulence factors. In the present study, we found that S. aureus strain Reynolds (CP5) cultured with SAL was internalized by MAC-T cells in larger numbers than strain Reynolds organisms not exposed to SAL. Furthermore, the internalization of the isogenic nonencapsulated Reynolds strain into MAC-T cells was not significantly affected by preexposure to SAL. Pretreatment of S. aureus strain Newman with SAL also enhanced internalization into MAC-T …
Role Of Pknb Kinase In Antibiotic Resistance And Virulence In Community-Acquired Methicillin-Resistant Staphylococcus Aureus Strain Usa300, S. Tamber, J. Schwartzman, A. L. Cheung
Role Of Pknb Kinase In Antibiotic Resistance And Virulence In Community-Acquired Methicillin-Resistant Staphylococcus Aureus Strain Usa300, S. Tamber, J. Schwartzman, A. L. Cheung
Dartmouth Scholarship
The regulation of cellular processes by eukaryote-like serine/threonine kinases is widespread in bacteria. In the last 2 years, several studies have examined the role of serine/threonine kinases in Staphylococcus aureus on cell wall metabolism, autolysis, and virulence, mostly in S. aureus laboratory isolates in the 8325-4 lineage. In this study, we showed that the pknB gene (also called stk1) of methicillin-resistant S. aureus (MRSA) strain COL and the community-acquired MRSA (CA-MRSA) strain USA300 is involved in cell wall metabolism, with the pknB mutant exhibiting enhanced sensitivity to β-lactam antibiotics but not to other classes of antibiotics, including aminoglycosides, ciprofloxacin, …
Proteolytic Regulation Of Toxin-Antitoxin Systems By Clppc In Staphylococcus Aureus, Niles P. Donegan, Earl T. Thompson, Zhibiao Fu, Ambrose L. Cheung
Proteolytic Regulation Of Toxin-Antitoxin Systems By Clppc In Staphylococcus Aureus, Niles P. Donegan, Earl T. Thompson, Zhibiao Fu, Ambrose L. Cheung
Dartmouth Scholarship
Bacterial toxin-antitoxin (TA) systems typically consist of a small, labile antitoxin that inactivates a specific longer-lived toxin. In Escherichia coli, such antitoxins are proteolytically regulated by the ATP-dependent proteases Lon and ClpP. Under normal conditions, antitoxin synthesis is sufficient to replace this loss from proteolysis, and the bacterium remains protected from the toxin. However, if TA production is interrupted, antitoxin levels decrease, and the cognate toxin is free to inhibit the specific cellular component, such as mRNA, DnaB, or gyrase. To date, antitoxin degradation has been studied only in E. coli, so it remains unclear whether similar mechanisms of regulation …
Levels Of The Secreted Vibrio Cholerae Attachment Factor Gbpa Are Modulated By Quorum-Sensing-Induced Proteolysis, Brooke A. Jude, Raquel M. Martinez, Karen Skorupski, Ronald K. Taylor
Levels Of The Secreted Vibrio Cholerae Attachment Factor Gbpa Are Modulated By Quorum-Sensing-Induced Proteolysis, Brooke A. Jude, Raquel M. Martinez, Karen Skorupski, Ronald K. Taylor
Dartmouth Scholarship
Vibrio cholerae is the etiologic agent of cholera in humans. Intestinal colonization occurs in a stepwise fashion, initiating with attachment to the small intestinal epithelium. This attachment is followed by expression of the toxin-coregulated pilus, microcolony formation, and cholera toxin (CT) production. We have recently characterized a secreted attachment factor, GlcNAc binding protein A (GbpA), which functions in attachment to environmental chitin sources as well as to intestinal substrates. Studies have been initiated to define the regulatory network involved in GbpA induction. At low cell density, GbpA was detected in the culture supernatant of all wild-type (WT) strains examined. In …
Intracellular Bacteria Encode Inhibitory Snare-Like Proteins., Fabienne Paumet, Jordan Wesolowski, Alejandro Garcia-Diaz, Cedric Delevoye, Nathalie Aulner, Howard A Shuman, Agathe Subtil, James E Rothman
Intracellular Bacteria Encode Inhibitory Snare-Like Proteins., Fabienne Paumet, Jordan Wesolowski, Alejandro Garcia-Diaz, Cedric Delevoye, Nathalie Aulner, Howard A Shuman, Agathe Subtil, James E Rothman
Department of Microbiology and Immunology Faculty Papers
Pathogens use diverse molecular machines to penetrate host cells and manipulate intracellular vesicular trafficking. Viruses employ glycoproteins, functionally and structurally similar to the SNARE proteins, to induce eukaryotic membrane fusion. Intracellular pathogens, on the other hand, need to block fusion of their infectious phagosomes with various endocytic compartments to escape from the degradative pathway. The molecular details concerning the mechanisms underlying this process are lacking. Using both an in vitro liposome fusion assay and a cellular assay, we showed that SNARE-like bacterial proteins block membrane fusion in eukaryotic cells by directly inhibiting SNARE-mediated membrane fusion. More specifically, we showed that …
Flagellum-Mediated Biofilm Defense Mechanisms Of Pseudomonas Aeruginosa Against Host-Derived Lactoferrin, Jeff G. Leid, Mathias Kerr, Candice Selgado, Chelsa Johnson, Gabriel Moreno, Alyssa Smith, Mark E. Shirtliff, Georg A. O'Toole, Emily K. Cope
Flagellum-Mediated Biofilm Defense Mechanisms Of Pseudomonas Aeruginosa Against Host-Derived Lactoferrin, Jeff G. Leid, Mathias Kerr, Candice Selgado, Chelsa Johnson, Gabriel Moreno, Alyssa Smith, Mark E. Shirtliff, Georg A. O'Toole, Emily K. Cope
Dartmouth Scholarship
Chronic infection with the gram-negative organism Pseudomonas aeruginosa is a leading cause of morbidity and mortality in human patients, despite high doses of antibiotics used to treat the various diseases this organism causes. These infections are chronic because P. aeruginosa readily forms biofilms, which are inherently resistant to antibiotics as well as the host's immune system. Our laboratory has been investigating specific mutations in P. aeruginosa that regulate biofilm bacterial susceptibility to the host. To continue our investigation of the role of genetics in bacterial biofilm host resistance, we examined P. aeruginosa biofilms that lack the flgK gene. This mutant …
The Effects Of Host Physiological Conditions On The Expression Of Icsp In Shigella Flexneri, Karen Levy, Helen Wing
The Effects Of Host Physiological Conditions On The Expression Of Icsp In Shigella Flexneri, Karen Levy, Helen Wing
Undergraduate Research Opportunities Program (UROP)
Shigella flexneri is a gram-negative bacterium capable of causing diarrhea and dysentery known as shigellosis. It is estimated there are 167.4 million shigellosis episodes throughout the world each year causing 1.1 million deaths. Shigella invades cells in the lower intestine through an induced phagocytosis. Once in the cytoplasm, bacteria move from one cell to another using actin-based motility. The Shigella outer membrane protease IcsP regulates actin-based motility and cell-to-cell spread by cleaving the actin assembly protein IcsA from the bacterial cell surface. We hypothesize that IcsP may serve additional functions during infection. By examining which environmental signals trigger icsP expression, …
Characterization Of The Omptin Protease, Ompt, In Escherichia Coli, Amanda Yates, Eun-Hae Kim, Helen Wing
Characterization Of The Omptin Protease, Ompt, In Escherichia Coli, Amanda Yates, Eun-Hae Kim, Helen Wing
Undergraduate Research Opportunities Program (UROP)
Omptins are outer membrane proteases found in gram negative bacteria that cause diseases in humans, such as pathogenic Escherichia coli, Shigella flexneri, Salmonella typhimurium, and Yersinia pestis. Bacterial species that express omptins cause diseases such as highly fatal plague and severe diarrhea and dysentery. The genes that encode these proteases are ompT, icsP, pgtE, and pla, respectively. These proteases are highly related in structure and share approximately 50% sequence identity. In S. flexneri, IcsP has been shown to cleave a key virulence determinant, IcsA (Egile et al., 1997). IcsA recruits host actin and allows for intracellular movement within host cells …
Genetic Evidence For An Alternative Citrate-Dependent Biofilm Formation Pathway In Staphylococcus Aureus That Is Dependent On Fibronectin Binding Proteins And The Grars Two-Component Regulatory System, Robert M. Q. Shanks, Michael A. Meehl, Kimberly M. Brothers, Raquel M. Martinez, Niles P. Donegan, Martha L. Graber, Ambrose L. Cheung, George A. O'Toole
Genetic Evidence For An Alternative Citrate-Dependent Biofilm Formation Pathway In Staphylococcus Aureus That Is Dependent On Fibronectin Binding Proteins And The Grars Two-Component Regulatory System, Robert M. Q. Shanks, Michael A. Meehl, Kimberly M. Brothers, Raquel M. Martinez, Niles P. Donegan, Martha L. Graber, Ambrose L. Cheung, George A. O'Toole
Dartmouth Scholarship
We reported previously that low concentrations of sodium citrate strongly promote biofilm formation by Staphylococcus aureus laboratory strains and clinical isolates. Here, we show that citrate promotes biofilm formation via stimulating both cell-to-surface and cell-to-cell interactions. Citrate-stimulated biofilm formation is independent of the ica locus, and in fact, citrate represses polysaccharide adhesin production. We show that fibronectin binding proteins FnbA and FnbB and the global regulator SarA, which positively regulates fnbA and fnbB gene expression, are required for citrate's positive effects on biofilm formation, and citrate also stimulates fnbA and fnbB gene expression. Biofilm formation is also stimulated by several …
In Vitro Analysis Of Tobramycin-Treated Pseudomonas Aeruginosa Biofilms On Cystic Fibrosis-Derived Airway Epithelial Cells, Gregory G. Anderson, Sophie Moreau-Marquis, Bruce A. Stanton, George A. O'Toole
In Vitro Analysis Of Tobramycin-Treated Pseudomonas Aeruginosa Biofilms On Cystic Fibrosis-Derived Airway Epithelial Cells, Gregory G. Anderson, Sophie Moreau-Marquis, Bruce A. Stanton, George A. O'Toole
Dartmouth Scholarship
P. aeruginosa forms biofilms in the lungs of individuals with cystic fibrosis (CF); however, there have been no effective model systems for studying biofilm formation in the CF lung. We have developed a tissue culture system for growth of P. aeruginosa biofilms on CF-derived human airway cells that promotes the formation of highly antibiotic-resistant microcolonies, which produce an extracellular polysaccharide matrix and require the known abiotic biofilm formation genes flgK and pilB. Treatment of P. aeruginosa biofilms with tobramycin reduced the virulence of the biofilms both by reducing bacterial numbers and by altering virulence gene expression. We performed microarray analysis …
Functional Taxonomy Of Bacterial Hyperstructures, Vic Norris, Tanneke Den Blaauwen, Armelle Cabin-Flaman, Roy H Doi, Rasika Harshey, Laurent Janniere, Alfonso Jimenez-Sanchez, Ding Jun Jin, Petra Anne Levin, Eugenia Mileykovskaya, Abraham Minsky, Milton Saier, Kirsten Skarstad
Functional Taxonomy Of Bacterial Hyperstructures, Vic Norris, Tanneke Den Blaauwen, Armelle Cabin-Flaman, Roy H Doi, Rasika Harshey, Laurent Janniere, Alfonso Jimenez-Sanchez, Ding Jun Jin, Petra Anne Levin, Eugenia Mileykovskaya, Abraham Minsky, Milton Saier, Kirsten Skarstad
Faculty, Staff and Student Publications
The levels of organization that exist in bacteria extend from macromolecules to populations. Evidence that there is also a level of organization intermediate between the macromolecule and the bacterial cell is accumulating. This is the level of hyperstructures. Here, we review a variety of spatially extended structures, complexes, and assemblies that might be termed hyperstructures. These include ribosomal or "nucleolar" hyperstructures; transertion hyperstructures; putative phosphotransferase system and glycolytic hyperstructures; chemosignaling and flagellar hyperstructures; DNA repair hyperstructures; cytoskeletal hyperstructures based on EF-Tu, FtsZ, and MreB; and cell cycle hyperstructures responsible for DNA replication, sequestration of newly replicated origins, segregation, compaction, and …
Transcutaneous Immunization With Toxin-Coregulated Pilin A Induces Protective Immunity Against Vibrio Cholerae O1 El Tor Challenge In Mice, Julianne E. Rollenhagen, Anuj Kalsy, Francisca Cerda, Manohar John
Transcutaneous Immunization With Toxin-Coregulated Pilin A Induces Protective Immunity Against Vibrio Cholerae O1 El Tor Challenge In Mice, Julianne E. Rollenhagen, Anuj Kalsy, Francisca Cerda, Manohar John
Dartmouth Scholarship
Toxin-coregulated pilin A (TcpA) is the main structural subunit of a type IV bundle-forming pilus of Vibrio cholerae, the cause of cholera. Toxin-coregulated pilus is involved in formation of microcolonies of V. cholerae at the intestinal surface, and strains of V. cholerae deficient in TcpA are attenuated and unable to colonize intestinal surfaces. Anti-TcpA immunity is common in humans recovering from cholera in Bangladesh, and immunization against TcpA is protective in murine V. cholerae models. To evaluate whether transcutaneously applied TcpA is immunogenic, we transcutaneously immunized mice with 100 mug of TcpA or TcpA with an immunoadjuvant (cholera toxin [CT], …
Prophylaxis And Therapy Of Inhalational Anthrax By A Novel Monoclonal Antibody To Protective Antigen That Mimics Vaccine-Induced Immunity, Laura Vitale, Diann Blanset, Israel Lowy, Thomas O'Neill, Joel Goldstein, Stephen F. Little, Gerard P. Andrews, Gary Dorough, Ronald K. Taylor, Tibor Keler
Prophylaxis And Therapy Of Inhalational Anthrax By A Novel Monoclonal Antibody To Protective Antigen That Mimics Vaccine-Induced Immunity, Laura Vitale, Diann Blanset, Israel Lowy, Thomas O'Neill, Joel Goldstein, Stephen F. Little, Gerard P. Andrews, Gary Dorough, Ronald K. Taylor, Tibor Keler
Dartmouth Scholarship
The neutralizing antibody response to the protective antigen (PA) component of anthrax toxin elicited by approved anthrax vaccines is an accepted correlate for vaccine-mediated protection against anthrax. We reasoned that a human anti-PA monoclonal antibody (MAb) selected on the basis of superior toxin neutralization activity might provide potent protection against anthrax. The fully human MAb (also referred to as MDX-1303 or Valortim) was chosen from a large panel of anti-PA human MAbs generated using transgenic mice immunized with recombinant PA solely on the basis of in vitro anthrax toxin neutralization. This MAb was effective in prophylactic and postsymptomatic treatment of …
Staphylococcus Aureus Escapes More Efficiently From The Phagosome Of A Cystic Fibrosis Bronchial Epithelial Cell Line Than From Its Normal Counterpart, Todd M. Jarry, Ambrose L. Cheung
Staphylococcus Aureus Escapes More Efficiently From The Phagosome Of A Cystic Fibrosis Bronchial Epithelial Cell Line Than From Its Normal Counterpart, Todd M. Jarry, Ambrose L. Cheung
Dartmouth Scholarship
Staphylococcus aureus is frequently the initial bacterium isolated from young cystic fibrosis (CF) patients, and yet its role in CF disease progression has not been determined. Recent data from our lab demonstrates that S. aureus can invade and replicate within the CF tracheal epithelial cell line (CFT-1). Here we describe the finding that the fate of internalized S. aureus in CFT-1 cells differs from its complemented counterpart (LCFSN). S. aureus strain RN6390 was able to replicate within the mutant CFT-1 cells after invasion but not in the complemented LCFSN cells. At 1 h postinvasion, S. aureus containing vesicles within both …
Do Cd1-Restricted T Cells Contribute To Antibody-Mediated Immunity Against Mycobacterium Tuberculosis?, Mark L. Lang, Aharona Glatman-Freedman
Do Cd1-Restricted T Cells Contribute To Antibody-Mediated Immunity Against Mycobacterium Tuberculosis?, Mark L. Lang, Aharona Glatman-Freedman
Dartmouth Scholarship
No abstract provided.
Transposon Disruption Of The Complex I Nadh Oxidoreductase Gene (Snod) In Staphylococcus Aureus Is Associated With Reduced Susceptibility To The Microbicidal Activity Of Thrombin-Induced Platelet Microbicidal Protein 1, Arnold S. Bayer, Peter Mcnamara, Michael R. Yeaman, Natalie Lucindo, Tiffanny Jones, Ambrose L. Cheung
Transposon Disruption Of The Complex I Nadh Oxidoreductase Gene (Snod) In Staphylococcus Aureus Is Associated With Reduced Susceptibility To The Microbicidal Activity Of Thrombin-Induced Platelet Microbicidal Protein 1, Arnold S. Bayer, Peter Mcnamara, Michael R. Yeaman, Natalie Lucindo, Tiffanny Jones, Ambrose L. Cheung
Dartmouth Scholarship
The cationic molecule thrombin-induced platelet microbicidal protein 1 (tPMP-1) exerts potent activity against Staphylococcus aureus. We previously reported that a Tn551 S. aureus transposon mutant, ISP479R, and two bacteriophage back-transductants, TxA and TxB, exhibit reduced in vitro susceptibility to tPMP-1 (tPMP-1(r)) compared to the parental strain, ISP479C (V. Dhawan, M. R. Yeaman, A. L. Cheung, E. Kim, P. M. Sullam, and A. S. Bayer, Infect. Immun. 65:3293-3299, 1997). In the current study, the genetic basis for tPMP-1(r) in these mutants was identified. GenBank homology searches using sequence corresponding to chromosomal DNA flanking Tn551 mutant strains showed that the fourth gene …
Rhamnolipids Modulate Swarming Motility Patterns Of Pseudomonas Aeruginosa, Nicky C. Caiazza, Robert M. Q. Shanks, G. A. O'Toole
Rhamnolipids Modulate Swarming Motility Patterns Of Pseudomonas Aeruginosa, Nicky C. Caiazza, Robert M. Q. Shanks, G. A. O'Toole
Dartmouth Scholarship
Pseudomonas aeruginosa is capable of twitching, swimming, and swarming motility. The latter form of translocation occurs on semisolid surfaces, requires functional flagella and biosurfactant production, and results in complex motility patterns. From the point of inoculation, bacteria migrate as defined groups, referred to as tendrils, moving in a coordinated manner capable of sensing and responding to other groups of cells. We were able to show that P. aeruginosa produces extracellular factors capable of modulating tendril movement, and genetic analysis revealed that modulation of these movements was dependent on rhamnolipid biosynthesis. An rhlB mutant (deficient in mono- and dirhamnolipid production) and …