Dissertation
Molecular mechanisms of Chlamydia trachomatis host cell focal adhesion stabilization
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000003159
Handle:
https://hdl.handle.net/2376/122112
Abstract
The rapid turnover of mucosal epithelial cells helps protect against bacterial infection. Prompt expulsion of infected cells can impede bacterial colonization and prevent bacterial spreading. Several intracellular pathogens have been shown to counteract this anti-microbial defense by stabilizing host cell adherence. We have demonstrated that Chlamydia trachomatis, an obligate intracellular pathogen, also modulates the number and stability of host cell focal adhesion (FA) complexes during infection. Furthermore, multiple chlamydial species were shown to enhance FA numbers, indicating FA modulation is a pan-chlamydial virulence strategy. Chlamydia undergoes a biphasic life cycle in which it loses infectivity during replication. Given its unique biology, it is likely distinctly vulnerable to cell exfoliation. Therefore, it is unsurprising that Chlamydia has evolved several cooperative mechanisms by which to modulate cellular adherence. Herein, we utilize quantitative confocal and live cell microscopy to further characterize a role for the type III secreted-effector proteins, TarP and CTL0480, in the modulation of host cell FAs. TarP was found to perform a post-invasion role, through direct localization to FAs during infection. This localization required a specific domain at the C-terminus of TarP. Ectopically expressed TarP was sufficient to mimic many of the infection-dependent changes to host cells (e.g. FA stability and restricted cell motility). Studies utilizing a TarP mutant revealed a reduced number of FAs. Thus, Chlamydia inserts TarP within FAs to alter their stability and enhance FA numbers. Interestingly, cells infected with a CTL0480 mutant had numerous, but significantly smaller FAs. The size of a FA is tied to its maturation state. We determined that FAs of Chlamydia-infected cells were more likely to possess the maturation marker zyxin and also displayed an increased number of central, fibrillar adhesions in a CTL0480-dependent manner. We propose that enhanced FA maturation is the mechanism driving the hyper-stability of FAs observed during infection. In addition, infected cells were found to have thick, stable stress fibers. Together, TarP and CTL0480 coordinate profound cytoskeletal modifications, which serve to stabilize host cell adherence.
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Details
- Title
- Molecular mechanisms of Chlamydia trachomatis host cell focal adhesion stabilization
- Creators
- Korinn Nicole Murphy
- Contributors
- Rey A. Carabeo (Advisor)Michael E. Konkel (Committee Member)Jennifer L. Watts (Committee Member)Joy Winuthayanon (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Molecular Biosciences, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 235
- Identifiers
- 99900652004401842
- Language
- English
- Resource Type
- Dissertation