Award Date

2009

Degree Type

Thesis

Degree Name

Master of Science in Biochemistry

Department

Chemistry

Advisor 1

Ernesto Abel-Santos, Committee Chair

First Committee Member

Chulsung Bae

Second Committee Member

Ronald Gary

Graduate Faculty Representative

Helen Wing

Number of Pages

144

Abstract

Eight years after the lamentable anthrax attacks, major scientific effort continues to be done, in order to stop imminent acts of bioterrorism. Innovative ways of therapy against the anthrax disease are being investigated. B. anthracis, the etiological agent of the infection, has a dormant stage in its life cycle known as the endospore. When conditions become favorable spores germinate, transforming into vegetative bacteria. In inhalational anthrax, the most fatal manifestation of the disease, spores enter the organism through the respiratory track, and are phagocytosized by alveolar macrophages of the lungs. Spores are able to sense nutrient availability, activating their germination inside the phagosomal compartment. Germination is a crucial step for the commencement of the pathogenesis inside the host organism.

B. anthracis germination is activated by a wide variety of amino acids and purine nucleosides. Inosine and alanine are the two most potent nutrient germinants. Recent studies have shown that germination can be hindered by isomers or structural analogues of germinants. 6-thioguanosine, a guanosine analogue, is able to inhibit germination, and prevent B. anthracis toxin-mediated necrosis in murine macrophages.

Our investigation was focused on the screening of 43 different purine nucleoside analogues, to determine their protective effects on the macrophage cell line J774a.1. We have selected a group of 19 compounds that impeded the spore germination in vitro, and tested their protective effect in cells. Seven of these analogues exerted protective effect against B. anthracis mediated killing. Structure activity relationships analyses on those compounds has clarified the mechanisms of the inhibition in cells, and illustrated a plausible model for the germinant-receptor recognition. Continuous research on this area should develop a novel antigerminant agent as an immediate prophylaxis to stop B. anthracis pathogenesis.

Keywords

6-thioguanosine; Anthrax disease; Bacillus anthracis; Germination; Inhibition; Isomers; Macrophages; Nucleoside inhibitors

Disciplines

Bacterial Infections and Mycoses | Bacteriology | Biochemistry | Cell Biology

Language

English


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