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Assembly And Display Of Surface Proteins In Actinomyces Oris, Sara Siegel

Dissertations & Theses (Open Access)

Bacteria are an integral part of human health and disease. In the human host, dental plaques form as a result of up to 700 individual bacterial species colonizing oral surfaces and forming a multispecies biofilm. These biofilms are the cause of prevalent human diseases such as dental caries, gingivitis, and periodontitis. The microbes present in the oral biofilm are highly spatially and temporally structured and require a primary colonizing species to adhere to host tissue. As an important primary colonizer of the oral biofilm, the actinobacterium Actinomyces oris utilizes cell wall anchored proteins and glycoconjugates to initiate adherence to host …

Mechanism Of Candida Albicans Biofilm And Virulence Inhibition By A Bacterial Secreted Factor, Carrie Graham

Dissertations & Theses (Open Access)

The human microbiome is a diverse polymicrobial population comprised of both fungi and bacteria. Perturbations of the normal microbiome can have a profound impact on health, including the development of infections. Exploitation of these polymicrobial interactions has the potential to provide novel treatment and prevention strategies for infectious diseases. Enterococcus faecalis, a Gram-positive bacterium, and Candida albicans, a polymorphic fungus, occupy overlapping niches as ubiquitous constituents of the gastrointestinal and oral microbiome. Both species are also amongst the most important and problematic, opportunistic nosocomial pathogens and are often co-isolated during infection. Surprisingly, these two species antagonize each other’s …

Oxidative Protein Folding Pathways In Gram-Positive Actinobacteria, Melissa E. Robinson

Dissertations & Theses (Open Access)

Disulfide bonds are important for the stability of many secreted proteins. These covalent linkages, which result from the oxidation of neighboring cysteine (Cys) residues, are often rate-limiting steps for protein folding and maturation. Disulfide bond formation is restricted to extracellular oxidizing compartments like the eukaryotic endoplasmic reticulum and Gram-negative bacterial periplasm. Protein oxidation has been well-studied in these organisms, but largely ignored in Gram-positive bacteria. Due to the absence of an outer membrane, these organisms are thought to lack compartments in which to catalyze oxidative protein folding.

This thesis reveals that Gram-positive Actinobacteria use disulfide bond formation to help fold …