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Articles 1 - 7 of 7
Full-Text Articles in Medicine and Health Sciences
Identification Of Two Gene Clusters And A Transcriptional Regulator Required For Pseudomonas Aeruginosa Glycine Betaine Catabolism, Matthew J. Wargo, Benjamin S. Szwergold, Deborah A. Hogan
Identification Of Two Gene Clusters And A Transcriptional Regulator Required For Pseudomonas Aeruginosa Glycine Betaine Catabolism, Matthew J. Wargo, Benjamin S. Szwergold, Deborah A. Hogan
Dartmouth Scholarship
Glycine betaine (GB), which occurs freely in the environment and is an intermediate in the catabolism of choline and carnitine, can serve as a sole source of carbon or nitrogen in Pseudomonas aeruginosa. Twelve mutants defective in growth on GB as the sole carbon source were identified through a genetic screen of a nonredundant PA14 transposon mutant library. Further growth experiments showed that strains with mutations in two genes, gbcA (PA5410) and gbcB (PA5411), were capable of growth on dimethylglycine (DMG), a catabolic product of GB, but not on GB itself. Subsequent nuclear magnetic resonance (NMR) experiments with 1,2-(13)C-labeled choline …
Mgra Represses Biofilm Formation In Staphylococcus Aureus, Maria P. Trotonda, Sandeep Tamber, Guido Memmi, Ambrose L. Cheung
Mgra Represses Biofilm Formation In Staphylococcus Aureus, Maria P. Trotonda, Sandeep Tamber, Guido Memmi, Ambrose L. Cheung
Dartmouth Scholarship
MgrA is a pleiotropic regulator that controls autolysis, virulence, and efflux pump activity in Staphylococcus aureus. We recently found that mgrA mutants of strains RN6390, SH1000, and MW2 also displayed enhanced biofilm formation compared with their respective parents. The biofilms formed by mgrA mutants of RN6390 and MW2 are independent of sigB and ica loci, two genetic elements that have been previously associated with biofilm formation in S. aureus. Biofilms formed by mgrA mutants are dependent on the expression of surface proteins mediated by the sortase gene srtA. Extracellular DNA was also a crucial component of the early biofilm of …
The Bile Response Repressor Brer Regulates Expression Of The Vibrio Cholerae Breab Efflux System Operon, Francisca A. Cerda-Maira, Carol S. Ringelberg, Ronald K. Taylor
The Bile Response Repressor Brer Regulates Expression Of The Vibrio Cholerae Breab Efflux System Operon, Francisca A. Cerda-Maira, Carol S. Ringelberg, Ronald K. Taylor
Dartmouth Scholarship
Enteric pathogens have developed several resistance mechanisms to survive the antimicrobial action of bile. We investigated the transcriptional profile of Vibrio cholerae O1 El Tor strain C6706 under virulence gene-inducing conditions in the presence and absence of bile. Microarray analysis revealed that the expression of 119 genes was affected by bile. The mRNA levels of genes encoding proteins involved in transport were increased in the presence of bile, whereas the mRNA levels of genes encoding proteins involved in pathogenesis and chemotaxis were decreased. This study identified genes encoding transcriptional regulators from the TetR family (vexR and breR) and …
Cif Is Negatively Regulated By The Tetr Family Repressor Cifr, Daniel P. Maceachran, Bruce A. Stanton, George A. O'Toole
Cif Is Negatively Regulated By The Tetr Family Repressor Cifr, Daniel P. Maceachran, Bruce A. Stanton, George A. O'Toole
Dartmouth Scholarship
We previously reported that the novel Pseudomonas aeruginosa toxin Cif is capable of decreasing apical membrane expression of the cystic fibrosis transmembrane conductance regulator (CFTR). We further demonstrated that Cif is capable of degrading the synthetic epoxide hydrolase (EH) substrate S-NEPC [(2S,3S)-trans-3-phenyl-2-oxiranylmethyl 4-nitrophenol carbonate], suggesting that Cif may be reducing apical membrane expression of CFTR via its EH activity. Here we report that Cif is capable of degrading the xenobiotic epoxide epibromohydrin (EBH) to its vicinal diol 3-bromo-1,2-propanediol. We also demonstrate that this epoxide is a potent inducer of cif gene expression. We show that the predicted TetR family transcriptional …
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 …
Repression Of Hla By Rot Is Dependent On Sae In Staphylococcus Aureus, Dongmei Li, Ambrose Cheung
Repression Of Hla By Rot Is Dependent On Sae In Staphylococcus Aureus, Dongmei Li, Ambrose Cheung
Dartmouth Scholarship
The regulatory locus sae is a two-component system in Staphylococcus aureus that regulates many important virulence factors, including alpha-toxin (encoded by hla) at the transcriptional level. The SarA homologs Rot and SarT were previously shown to be repressors of hla in selected S. aureus backgrounds. To delineate the interaction of rot and sae and the contribution of sarT to hla expression, an assortment of rot and sae isogenic single mutants, a rot sae double mutant, and a rot sae sarT markerless triple mutant were constructed from wild-type strain COL. Using Northern blot analysis and transcriptional reporter gene green fluorescent protein, …