Publication Date

2025

Advisor(s) - Committee Chair

Simran Banga, Joseph Marquardt, Kerrie McDaniel

Degree Program

Department of Biology

Degree Type

Master of Science

Abstract

Legionella pneumophila, the causative agent of Legionnaires' disease, utilizes a Type IV secretion system (T4SS) to transport effector proteins into host cells. This bacterium is said to have over 300 effector proteins. Among these, the Ceg10 effector protein had remained uncharacterized, despite evidence suggesting the importance of bacterial effector proteins in the host-pathogen interaction. This study aimed to perform a structural and functional characterization of Ceg10 through transcriptomic, bioinformatics, and molecular analyses. Transcriptomic profiling of HEK 293T cells expressing Ceg10 revealed significant differential gene expression, with approximately 20 upregulated genes, including leucine-rich repeat, as well as other downregulated genes. Furthermore, pathway analysis using KEGG and Pathview indicated that genes associated with lipid metabolism and PPAR signaling pathways were affected. Structural and bioinformatics analyses, alongside molecular docking, demonstrated binding between Ceg10 and PPARγ, particularly at the LXXL motif, a critical region for transcriptional coregulation interactions. To assess the impact on the PPAR signaling pathway, Western blot analysis utilizing PPAR and NF- κB antibodies was conducted. Ceg10, tagged with GFP, was expressed in Escherichia coli BL21 and subsequently transfected into HEK293T cells. However, Western blot analysis showed no specific changes in NF-kB expression in Ceg10, GFP, HEK 293T cells. This suggested that Ceg10 may not impact NF-kB pathway. We need to further explore if Ceg10 may modulate host lipid metabolism through direct or indirect interactions with PPAR. This study offers insights into Legionella-host interactions, potentially revealing therapeutic targets for bacterial infections that manipulate immune response pathways.

Disciplines

Bioinformatics | Biology | Life Sciences | Microbiology | Molecular Biology

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