Date on Master's Thesis/Doctoral Dissertation

8-2011

Document Type

Master's Thesis

Degree Name

M.S.

Department

Oral Biology

Committee Chair

Graham, James H.

Author's Keywords

M. tuberculosis; Transcriptional regulator; Rv1985c; Phagosome; Macrophage; Adaptation

Subject

Mycobacterium tuberculosis

Abstract

Mycobacterium tuberculosis causes the often-fatal infectious disease Tuberculosis, and infects approximately one third of the world's population. Gaining a better understanding of how these bacteria regulate gene expression for intracellular survival will likely aid in developing ways to reduce disease. Studies of bacterial RNA expression in experimentally infected primary human macrophages indicated open reading frame Rv1985c, encoding a putative transcriptional regulator, may contribute to intracellular survival. Comparison of a strain constitutively expressing Rv1985c and the isogenic wildtype parent by array hybridization identified genes potentially regulated by Rv1985c. These included a group encoding factors likely relevant to cell wall remodeling, particularly modification of mycolic acids. Interestingly, of the 22 upregulated genes identified by significance analysis of microarray, S.A.M., among the highest expressed were some of those previously described as part of the DosR/DevR dormancy regulon. We verified that Rv1985c mRNA levels rose dramatically in the first 24 hours following phagocytosis, and confirmed a lack of increased dosR/devR transcription in the constitutively expressing Rv1985c strain. Finally we showed that a Rv1985c knock out mutant while able to grow normally in laboratory broth had reduced ability to colonize cultured human macrophages, and showed reduced cytopathic effects. Restoring Rv1985c reversed this attenuation of the mutant.

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