Defense Date


Document Type


Degree Name

Doctor of Philosophy


Pharmaceutical Sciences

First Advisor

Aaron E. May


Antibiotics inhibit the growth or survival of bacteria by targeting their essential functions.1 Due to weaknesses in traditional antibiotics and the increasing prevalence of antibiotic resistance genes, virulence factors are being targeted for therapeutic treatment of bacterial infection.2 We have developed an assay to quantify and observe type III secretion system (T3SS) activity. The type III secretion system (T3SS) is a virulence factor present in some Gram-negative pathogens including enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC, respectively),3 and others.4–9 The T3SS between EPEC and EHEC are highly conserved and share over 90% sequence identity with the mouse pathogen Citrobacter rodentium.3,10,11 Because of the high similarity between the pathophysiology of these organisms, C. rodentium is often used as the mouse model of EPEC and EHEC infection.12–14 We have developed a construct of C. rodentium to produce carboxypeptidase G2 (CPG2), a eukaryotic enzyme that selectively cleaves glutamate residues. We have tagged CPG2 on the N-terminus with an amino acid sequence to target the enzyme for type III secretion.15 The CPG2 reporter assay was used to screen natural products for their ability to inhibit the T3SS.16–26

We also completed a high throughput screening campaign for the identification of inhibitors of phage-related ribosomal protease Prp. This protease is essential for ribosomal assembly in bacteria and previously reported knockdown studies have indicated that bacteria cannot survive without Prp. We have screened over 5000 compounds for their inhibitory activity.


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