Date of Award

12-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Biochemistry and Molecular Biology

Advisor

Temesvari, Lesly A

Committee Member

Kurtz , Harry

Committee Member

Sehorn , Michael

Committee Member

Smith , Kerry

Committee Member

Morris , Meredith

Abstract

Lipid rafts, sterol- and sphingolipid-rich membrane microdomains, have been shown to control virulence in a variety of parasites including Entamoeba histolytica, an intestinal parasite that causes dysentery and liver abscess. Parasite cell surface receptors, such as the Gal/GalNAc lectin, facilitate attachment to host cells and extracellular matrix. The Gal/GalNAc lectin binds to galactose or N-acetylgalactosamine residues on host components, and is composed of heavy (Hgl), intermediate (Igl), and light (Lgl) subunits. Although Igl is constitutively localized to lipid rafts, Hgl and Lgl transiently associate with this compartment in a cholesterol-dependent fashion. Exposure to bonafide Gal/GalNAc lectin ligands is associated with enrichment of the subunits in rafts. Direct lectin-ligand interactions and sufficient levels of both PIP2 and calcium were shown to be necessary for lectin enrichment in rafts. Additionally, an initial analysis of both post-translational modifications and protein interactions that regulate the association of the lectin subunits with rafts was performed. Glycosylation, palmitoylation, and GPI-anchoring were all shown to have possible roles in regulating the localization of the lectin subunits. Depolymerization of actin was shown to not affect the localization of any of the three subunit and no cytoskeletal elements were shown to regulate lectin localization in lipid rafts to date.

Included in

Biochemistry Commons

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