Microbiology Commons^™

Deconstructing Ihf-Mediated Inhibition Of The Complex Acs Promoter, David S. Thach

Dissertations

acs encodes a high affinity enzyme that permits survival during carbon starvation. As befits a survival gene, its transcription is subject to complex regulation. Previously, the Wolfe lab reported that CRP activates acs transcription by binding tandem DNA sites located upstream of the major acsP2 promoter and that the nucleoid protein IHF binds three specific sites located just upstream. The most proximal site (IHF III) exhibits reduced transcription compared to the full-length promoter or to a construct lacking all three IHF sites. The goal of my research was to understand how IHF III inhibits CRP-dependent acs transcription. First, I helped …

Hypervirulent Clostridium Difficile Strains: Adherence, Toxin Production And Sporulation, Michelle Marie Merrigan

Dissertations

Clostridium difficile is a leading cause of nosocomial infections, and recently emerged "hypervirulent" C. difficile strains have caused epidemics worldwide. We hypothesized that multiple factors were responsible for this phenotype, particularly the interaction of C. difficile with the epithelial cell, as well as toxin production and sporulation.

To test if host interaction varied in HV strains, we developed a quantitative host-cell adherence assay, and found that while C. difficile strains varied in adherence to human intestinal epithelial cells, hypervirulent strains were not significantly more adherent than other strains. The bacterial surface protein SlpA varied in both size and amount between …

Coronavirus Replicase Proteins: Multifunctional Mediators Of Replication And Innate Immunity Evasion, Mark Anthony Clementz

Dissertations

Coronaviruses are positive-sense, single-stranded RNA viruses. The majority of the RNA encodes non-structural proteins (nsps) that are translated as a large polyprotein, which is cleaved by the papain-like (PLP) and picornavirus 3C-like (3CLpro) proteases. The nsps modify host membranes to produce double membrane vesicles (DMVs) upon which the replicase-transcriptase assembles and synthesizes viral RNA. nsp3, nsp4, and nsp6 are integral membrane proteins believed to be involved in DMV formation. Work presented here demonstrates that nsp4 is subjected to N-linked glycosylation and mutation of N258 to threonine in nsp4 confers a temperature sensitive phenotype to MHV-A59 infectious clone virus. This virus …

Characterization Of Tram, A Required Bacteroides Fragilis Conjugal Apparatus Protein That Interacts With The B. Fragilis Putative Coupling Protein Bcta And The B. Fragilis Relaxase Protein Bmph, Mai Thi Thanh Nguyen

Dissertations

Bacteroides spp. organisms, the most prominent bacteria of the human colon, are reservoirs of antibiotic resistance genes which promiscuously transfer within and from the genus via conjugation. The B. fragilis clinical isolate LV23 harbors a 37kb conjugative transposon, BTF-37. Two important conjugal apparatus proteins encoded by BTF-37 are BctA, a predicted coupling protein (CP) that powers DNA translocation, and ORF7 (TraM). In this study, we demonstrated that TraM exhibits characteristics of a required conjugal apparatus protein including 1) upregulated expression under conjugation conditions; 2) localization to the bacterial inner membrane; 3) interaction with the putative coupling protein BctA and the …

Morphogenesis Of The Bacillus Anthracis Spore, Michael Mallozzi

Dissertations

With the ability to shut down metabolism, survive exposure to high degrees of heat, ultra-violet and ionizing radiation, digestive enzymes, and antimicrobials, the bacterial spore is one of the most-resistant forms of life on earth. Although most spores are harmless, several species' spores cause serious diseases such as tetanus, anthrax, gas gangrene, botulism, and diarrhea. Spore-forming bacteria differentiate into spores in response to stresses (especially starvation) in a multi-stage developmental pathway involving the coordinated expression of hundreds of genes and the formation of specialized protective organelles which surround and protect the spore during dormancy. The Bacillus anthracis spore (the causative …