Award Date

12-2010

Degree Type

Thesis

Degree Name

Master of Science in Biological Sciences

Department

Life Sciences

First Committee Member

Helen Wing, Chair

Second Committee Member

Eduardo Robleto

Third Committee Member

Brian Hedlund

Graduate Faculty Representative

Douglas Burke

Number of Pages

69

Abstract

Shigella flexneri is a species of Gram-negative intracellular pathogens that causes bacillary dysentery in humans. Shigella relies on the precise transcriptional regulation of virulence genes, encoded by a large virulence plasmid, for invasion and infection of human colonic epithelial cells. The transcription of most identified virulence genes are regulated through a cascade controlled by the primary regulator of virulence genes, VirF, and the global transcriptional regulator, VirB. Currently, few studies have addressed how individual Shigella virulence genes are precisely regulated for optimal expression during specific stages of pathogenesis and within the constraints of the regulatory cascade. This work addresses how individual virulence genes are regulated through the study of transcriptional regulation in four Shigella virulence genes, icsP, ipaJ, phoN1, and ipaH7.8. Analysis of the icsP gene has identified multiple promoters contributing to icsP transcription and to the regulation of IcsP protein production through the use of two different translation start sites. In addition, analyses of the ipaJ, phoN1, and ipaH7.8 genes has identified that the phoN1 gene is transcriptionally regulated by the CRP, suggesting that catabolite repression is involved with the regulation of some virulence genes in Shigella. Together, these data suggest that the transcriptional regulation of virulence genes in Shigella flexneri is more complex than previously observed.

Keywords

Bacterial transformation; Genetic transcription; IcsP; Microbial genetics; Shigella flexneri; Transcription factors

Disciplines

Genetics | Genetics and Genomics | Microbiology | Molecular Biology

Language

English


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