Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. John Geiser

Second Advisor

Dr. Bruce Bejcek

Third Advisor

Dr. Pamela Hoppe

Fourth Advisor

Dr. Wendy Ransom-Hodgkinis

Access Setting

Masters Thesis-Open Access


Human pathogenic Yersinia spp. utilize Type III Secretion to deliver six effector proteins into host cells. The injected proteins resemble eukaryotic signal transduction molecules and are capable of disrupting signaling pathways in order to subvert the functions of the targeted cell or disrupt communication with surrounding cells. As a result, bacterial invaders are not only able to survive the threat of a host immune response, but can thrive despite it. YopT is a cysteine protease that cleaves RhoGTPases, releasing them from the membrane and thus from their role as initiators of signaling pathways, including the nucleation of actin and formation of stress fibers, filopodia, and lamellipodia. This leads to disruption of the cytoskeleton, allowing pathogens to resist phagocytosis by professional phagocytes.

This study employs the yeast Saccharomyces cerevisiae as a model system and utilizes the techniques of yeast two-hybrid screening, generation of spontaneous mutant suppressors of YopT lethality, and immunofluorescent microscopy to gain a better understanding of the physical, molecular, and genetic basis of YopT lethality.

Included in

Biology Commons