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Full-Text Articles in Medical Microbiology
Structural Features Of The Pseudomonas Fluorescens Biofilm Adhesin Lapa Required For Lapg-Dependent Cleavage, Biofilm Formation, And Cell Surface Localization, Chelsea D. Boyd, T. Jarrod Smith, Sofiane El-Kirat-Chatel, Peter D. Newell, Yves F. Dufrêne, George A. O'Toole
Structural Features Of The Pseudomonas Fluorescens Biofilm Adhesin Lapa Required For Lapg-Dependent Cleavage, Biofilm Formation, And Cell Surface Localization, Chelsea D. Boyd, T. Jarrod Smith, Sofiane El-Kirat-Chatel, Peter D. Newell, Yves F. Dufrêne, George A. O'Toole
Dartmouth Scholarship
The localization of the LapA protein to the cell surface is a key step required by Pseudomonas fluorescens Pf0-1 to irreversibly attach to a surface and form a biofilm. LapA is a member of a diverse family of predicted bacterial adhesins, and although lacking a high degree of sequence similarity, family members do share common predicted domains. Here, using mutational analysis, we determine the significance of each domain feature of LapA in relation to its export and localization to the cell surface and function in biofilm formation. Our previous work showed that the N terminus of LapA is required for …
Non-Identity-Mediated Crispr-Bacteriophage Interaction Mediated Via The Csy And Cas3 Proteins, Kyle C. Cady, George A. O'Toole
Non-Identity-Mediated Crispr-Bacteriophage Interaction Mediated Via The Csy And Cas3 Proteins, Kyle C. Cady, George A. O'Toole
Dartmouth Scholarship
Studies of the Escherichia, Neisseria, Thermotoga, and Mycobacteria clustered regularly interspaced short palindromic repeat (CRISPR) subtypes have resulted in a model whereby CRISPRs function as a defense system against bacteriophage infection and conjugative plasmid transfer. In contrast, we previously showed that the Yersinia-subtype CRISPR region of Pseudomonas aeruginosa strain UCBPP-PA14 plays no detectable role in viral immunity but instead is required for bacteriophage DMS3-dependent inhibition of biofilm formation by P. aeruginosa. The goal of this study is to define the components of the Yersinia-subtype CRISPR region required to mediate this bacteriophage-host interaction. We show that the Yersinia-subtype-specific CRISPR-associated (Cas) proteins …
H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor
H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor
Dartmouth Scholarship
Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at …
Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés
Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés
Dartmouth Scholarship
The biofilm-associated protein Bap is a staphylococcal surface protein involved in biofilm formation. We investigated the influence of the global regulatory locus sarA on bap expression and Bap-dependent biofilm formation in three unrelated Staphylococcus aureus strains. The results showed that Bap-dependent biofilm formation was diminished in the sarA mutants by an agr-independent mechanism. Complementation studies using a sarA clone confirmed that the defect in biofilm formation was due to the sarA mutation. As expected, the diminished capacity to form biofilms in the sarA mutants correlated with the decreased presence of Bap in the bacterial surface. Using transcriptional fusion and …
Sara Is An Essential Positive Regulator Of Staphylococcus Epidermidis Biofilm Development, Maria A. Tormo, Miguel Marti, Jaione Valle, Adhar C. Manna
Sara Is An Essential Positive Regulator Of Staphylococcus Epidermidis Biofilm Development, Maria A. Tormo, Miguel Marti, Jaione Valle, Adhar C. Manna
Dartmouth Scholarship
Staphylococcus epidermidis biofilm formation is associated with the production of the polysaccharide intercellular adhesin (PIA)--poly-N-acetylglucosamine polysaccharide (PNAG) by the products of the icaADBC operon. Recent evidence indicates that SarA, a central regulatory element that controls the production of Staphylococcus aureus virulence factors, is essential for the synthesis of PIA/PNAG and the ensuing biofilm development in this species. Based on the presence of a sarA homolog, we hypothesized that SarA could also be involved in the regulation of the biofilm formation process in S. epidermidis. To investigate this, we constructed nonpolar sarA deletions in two genetically unrelated S. epidermidis clinical strains, …
Identification Of Sarv (Sa2062), A New Transcriptional Regulator, Is Repressed By Sara And Mgra (Sa0641) And Involved In The Regulation Of Autolysis In Staphylococcus Aureus, Adhar C. Manna, Susham S. Ingavale, Marybeth Maloney, Willem Van Wamel, Ambrose L. Cheung
Identification Of Sarv (Sa2062), A New Transcriptional Regulator, Is Repressed By Sara And Mgra (Sa0641) And Involved In The Regulation Of Autolysis In Staphylococcus Aureus, Adhar C. Manna, Susham S. Ingavale, Marybeth Maloney, Willem Van Wamel, Ambrose L. Cheung
Dartmouth Scholarship
The expression of genes involved in the pathogenesis of Staphylococcus aureus is known to be controlled by global regulatory loci, including agr, sarA, sae, arlRS, lytSR, and sarA-like genes. Here we described a novel transcriptional regulator called sarV of the SarA protein family. The transcription of sarV is low or undetectable under in vitro conditions but is significantly augmented in sarA and mgrA (norR or rat) (SA0641) mutants. The sarA and mgrA genes act as repressors of sarV expression, as confirmed by transcriptional fusion and Northern analysis data. Purified SarA and MgrA proteins bound specifically to separate regions of the …
The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski
The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski
Dartmouth Scholarship
Activation of the tcpPH promoter on the Vibrio pathogenicity island by AphA and AphB initiates the Vibrio cholerae virulence cascade and is regulated by quorum sensing through the repressive action of HapR on aphA expression. To further understand how the chromosomally encoded AphA protein activates tcpPH expression, site-directed mutagenesis was used to identify the base pairs critical for AphA binding and transcriptional activation. This analysis revealed a region of partial dyad symmetry, TATGCA-N6-TNCNNA, that is important for both of these activities. Searching the V. cholerae genome for this binding site permitted the identification of a second one upstream of a …
Mechanism Of Toxt-Dependent Transcriptional Activation At The Vibrio Cholerae Tcpa Promoter, Robin R. Hulbert, Ronald K. Taylor
Mechanism Of Toxt-Dependent Transcriptional Activation At The Vibrio Cholerae Tcpa Promoter, Robin R. Hulbert, Ronald K. Taylor
Dartmouth Scholarship
The AraC homolog ToxT coordinately regulates virulence gene expression in Vibrio cholerae. ToxT is required for transcriptional activation of the genes encoding cholera toxin and the toxin coregulated pilus, among others. In this work we focused on the interaction of ToxT with the tcpA promoter and investigated the mechanism of ToxT-dependent transcriptional activation at tcpA. Deletion analysis showed that a region from −95 to +2 was sufficient for ToxT binding and activation, both of which were simultaneously lost when the deletion was extended to −63. A collection of point mutations generated by error-prone PCR revealed two small regions required …