Defense Date


Document Type


Degree Name

Master of Science


Physiology and Biophysics

First Advisor

Dr. Janina Lewis

Second Advisor

Dr. Liya Qiao

Third Advisor

Dr. Roland Pittman

Fourth Advisor

Dr. Todd Kitten


Porphyromonas gingivalis, a gram-negative anaerobic, pathogenic bacterium is a major etiological agent in the initiation and progression of periodontal disease. Due to the ever-changing environment of the oral cavity, inhabitants like Porphyromonas gingivalis must possess the ability to adapt to changes in environmental conditions like pH, temperature, oxygen tension, and metal concentration. P. gingivalis should therefore have an efficient regulatory system in order to adapt and survive in the oral cavity. This response adaptation occurs at the transcriptional level, which involves alternative sigma factors. Extracytoplasmic function sigma (ECF-s) factors are the largest group of alternative sigma factors that play a role in the bacterial response to environmental stress conditions. Here we analyze the s-70 factor gene, PG0214, an extracytoplasmic function sigma factor encoded in the P. gingivalis genome, and examine its role in the bacterial response to environmental stress and virulence.

Our findings indicate that the PG0214 gene is important in regulating major functional gene groups and pathways in the P. gingivalis genome. Strains deficient in the PG0214 gene were analyzed and shown to have decreased protease activity, as well as reduced survivability and invasion rates in eukaryotic host cells when compared against wild-type W83 and ATCC 33277 strains.

Collectively our studies demonstrate that the PG0214 gene is a positive regulator of gene expression for the survival and virulence of P. gingivalis in the presence of oxidative- and iron-stress, although further study is needed to fully characterize the gene and determine its specific function.


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