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Full-Text Articles in Pathogenic Microbiology
Regulation Of Toxin Synthesis By Clostridium Difficile, Charles Darkoh
Regulation Of Toxin Synthesis By Clostridium Difficile, Charles Darkoh
Dissertations & Theses (Open Access)
Clostridium difficile is the leading definable cause of nosocomial diarrhea worldwide due to its virulence, multi-drug resistance, spore-forming ability, and environmental persistence. The incidence of C. difficile infection (CDI) has been increasing exponentially in the last decade. Virulent strains of C. difficile produce either toxin A and/or toxin B, which are essential for the pathogenesis of this bacterium. Current methods for diagnosing CDI are mostly qualitative tests that detect the bacterium, the toxins, or the toxin genes. These methods do not differentiate virulent C. difficile strains that produce active toxins from non-virulent strains that do not produce toxins or produce …
Functional Characterization Of Atxa, The Bacillus Anthracis Virulence Regulator, Troy G. Hammerstrom
Functional Characterization Of Atxa, The Bacillus Anthracis Virulence Regulator, Troy G. Hammerstrom
Dissertations & Theses (Open Access)
Coordinated expression of virulence genes in Bacillus anthracis occurs via a multi-faceted signal transduction pathway that is dependent upon the AtxA protein. Intricate control of atxA gene transcription and AtxA protein function have become apparent from studies of AtxA-induced synthesis of the anthrax toxin proteins and the poly-D-glutamic acid capsule, two factors with important roles in B. anthracis pathogenesis. The amino-terminal region of the AtxA protein contains winged-helix (WH) and helix-turn-helix (HTH) motifs, structural features associated with DNA-binding. Using filter binding assays, I determined that AtxA interacted non-specifically at a low nanomolar affinity with a target promoter (Plef) …
Control Of The Master Virulence Regulatory Gene Atxa In Bacillus Anthracis, Jennifer L. Dale
Control Of The Master Virulence Regulatory Gene Atxa In Bacillus Anthracis, Jennifer L. Dale
Dissertations & Theses (Open Access)
Transcription of the Bacillus anthracis structural genes for the anthrax toxin proteins and biosynthetic operon for capsule are positively regulated by AtxA, a transcription regulator with unique properties. Consistent with the role of atxA in virulence factor expression, a B. anthracis atxA-null mutant is avirulent in a murine model for anthrax. In batch culture, multiple signals impact atxA transcript levels, and the timing and steady state level of atxA expression is critical for optimal toxin and capsule synthesis. Despite the apparent complex control of atxA transcription, only one trans-acting protein, the transition state regulator AbrB, has been demonstrated …