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Date of Award

Spring 2010

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Dr. Laura Runyen-Janecky

Abstract

Shigella flexneri possesses several two-component regulatory systems (TCRSs), which are responsible for sensing changes in environmental conditions and regulating gene expression accordingly. The BaeSR, CreBC, EvgSA and NtrBC TCRSs were examined for potential roles in the virulence of S. flexneri. Nac, a transcriptional regulator involved in nitrogen metabolism, is a downstream target gene of NtrBC which was also examined for importance. Null mutants of each TCRS and Nac were constructed and compared with wild type Shigella in several assays. None of the TCRSs appeared to be important for invasion of intestinal epithelial cells or for resistance to the antimicrobial compound, magainin II. Also, evgSA did not appear to be important for adaptation to high osmolarity environments. None of the TCRSs or Nac appeared to be important for survival of Shigella within macrophages. However, ntrBC was found to be important for the formation of plaques in Henle cells. Furthermore, both the nac-dependent and nac-independent sets of genes regulated by NtrBC were found to be important for Shigella plaque formation in Henle cells. These results suggest that NtrBC and Nac positively regulate expression of genes which are required for survival, multiplication or intercellular spread of S. flexneri in Henle cells.

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