GSBS Dissertations and Theses

Approval Date

12-18-2015

Document Type

Doctoral Dissertation

Academic Program

Biochemistry and Molecular Pharmacology

Department

Biochemistry and Molecular Pharmacology

First Thesis Advisor

Mary Munson, PhD

Keywords

SNARE Proteins, Saccharomyces cerevisiae Proteins, Vesicular Transport Proteins, Exocysts, Exocyst Subunit Sec6

Subjects

Dissertations, UMMS; SNARE Proteins; Saccharomyces cerevisiae Proteins; Vesicular Transport Proteins

Abstract

In eukaryotic cells, membrane-bound vesicles carry cargo between intracellular compartments, to and from the cell surface, and to the extracellular environment. Many conserved families of proteins are required for properly localized vesicle fusion, including the multi-subunit tethering complexes and the SNARE complexes. These protein complexes work together to promote proper vesicle fusion in other trafficking pathways. Contrary to these other pathways, our lab previously suggested that the exocyst subunit Sec6, a component of the exocytosis-specific tethering complex, inhibited Sec9:Sso1 SNARE complex assembly due to interactions in vitro with the SNARE protein Sec9 (Sivaram et al., 2005).

My goal for this project was to test the hypothesis that Sec6 inhibited SNARE complex assembly in vivo. I therefore chose to generate Sec6:Sec9 loss-of-binding mutants, and study their effect both in vitro and in vivo. I identified a patch of residues on Sec9 that, when mutated, are sufficient to disrupt the novel Sec6-SNARE interaction. Additionally, I found that the previous inhibitory role for Sec6 in SNARE assembly was due to a data mis-interpretation; my re-interpretation of the data shows that Sec6 has a mild, if any, inhibitory effect on SNARE assembly. My results suggest a potential positive role for Sec6 in SNARE complex assembly, similar to the role observed for other tether-SNARE interactions.

DOI

10.13028/M2B01M

Rights and Permissions

Copyright is held by the author, with all rights reserved.

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