Date of Award

12-1-2014

Degree Name

Master of Science

Department

Molecular Biology Microbiology and Biochemistry

First Advisor

Fix, Douglas

Abstract

Group A Streptococcus (GAS) is responsible for mild and common infections like tonsillitis and pharyngitis, and more serious invasive disorders like necrotizing fasciitis and glomerulonephritis. The ability to invade tissues is closely linked to the virulence factors expressed by the bacterium. Hyaluronic acid capsule expression is variable among all the strains in S. pyogenes and confers the capacity to evade the immune response. In a previous study, it was found that capsule production in CovR mutants was temperature-regulated, showing a basal level of capsule production at 37℃ but increased production was observed at 25℃. Moreover, it was found that when CvfA, an endoribonuclease, is mutated, this thermoregulation is abolished. Since an antisense RNA was found spanning the entire capsule operon, another ribonuclease, RNaseIII which is involved in dsRNA digestion, was considered as a possible candidate to regulate the antisense and capsule transcripts. In this study, the objective is to find if and how the ribonucleases regulate the capsule transcript and antisense RNA. Data suggests that RNaseIII does not have a role in the regulation. On the other hand, CvfA showed a key role in regulating transcript levels. Furthermore, temperature appears to have some effect on its activity.

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