ORCID ID
Graduation Date
Spring 5-10-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Programs
Genetics, Cell Biology & Anatomy
First Advisor
Stacey D. Gilk
Abstract
Coxiella burnetii is a highly infectious and environmentally persistent bacterium that causes the disease Q Fever. Its intracellular home, the Coxiella-Containing Vacuole (CVV), is formed from fusion of host-derived vesicles and is rich in sterols - yet cholesterol accumulation in the CCV is bacteriolytic. Our lab’s goal is to understand how Coxiella manages intracellular cholesterol levels and survives within the host. One way Coxiella may modulate CCV cholesterol is through membrane contact sites (MCS), areas where molecular complexes bridge two organelles and exchange lipids. This thesis explores how Coxiella uses both a mammalian lipid transfer protein and bacterially-encoded effector proteins to control MCS with the endoplasmic reticulum (ER). The mammalian protein, ORP1L, localizes to the CCV and mediates CCV-ER MCS. ORP1L localization depends on the Coxiella Type 4B Secretion System (T4BSS), which secretes bacterial effector proteins into the host cytosol to manipulate pathways and increase bacterial survival. I showed that Coxiella uses ORP1 to lower CCV cholesterol and increase bacterial growth in macrophages. Additionally, our lab identified nine Coxiella T4BSS effector proteins with putative FFAT motifs, special protein sequences that indicate potential interaction with VAPs, a family of ER proteins known to form MCS. I found that one of these proteins, CBU1751, interacts with VAPA and VAPB through a two-hybrid assay but not by co-immunoprecipitation. Future work will clarify the mechanism by which ORP1 lowers CCV cholesterol and interrogate whether CBU1751 interacts with VAPs to form plasma membrane-ER MCS.
Recommended Citation
Sladek, Margaret F., "Coxiella burnetii Manipulation of Membrane Contact Sites in the Intracellular Niche" (2025). Theses & Dissertations. 909.
https://digitalcommons.unmc.edu/etd/909
License to use excerpt from ORP1 paper.pdf (265 kB)
License to use ORP1 paper figure.pdf (265 kB)
Comments
2025 Copyright, the authors