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Title:Single-molecule fluorescence resonance energy transfer study of SNARE-mediated membrane fusion
Author(s):Diao, Jiajie
Director of Research:Ha, Taekjip
Doctoral Committee Chair(s):Chemla, Yann R.
Doctoral Committee Member(s):Ha, Taekjip; Rogers, John A.; Aksimentiev, Aleksei
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Single molecule
Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)
Membrane fusion
Abstract:This is a comprehensive study of protein-mediated membrane fusion through single-molecule fluorescence resonance energy transfer (smFRET). Membrane fusion is one of the important cellular processes by which two initially distinct lipid bilayers merge their hydrophobic cores, resulting in one interconnected structure. For example, exocytosis, fertilization of an egg by a sperm and communication between neurons are a few among many processes that rely on some form of fusion. Proteins called soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) play a central role in fusion processes which is also regulated by many accessory proteins, such as synaptotagmin, complexin and Munc18. By a new lipid mixing method at the single-vesicle level, we are able to accurately detect different stages of SNARE-mediated membrane fusion including docking, hemi and full fusion via FRET value of single donor/acceptor vesicle pair. Through this single-vesicle lipid mixing assay, we discovered the vesicle aggregation induced by C2AB/Ca2+, the dual function of complexin, and the fusion promotion role of Munc18/SNARE-core binding mode. While this new method provides the information regarding the extent of the ensemble lipid mixing, the fusion pore opening between two vesicular cavities and the interaction between proteins cannot be detected. In order to overcome these limitations, we then developed a single-vesicle content mixing method to reveal the key factor of pore expansion by detecting the FRET change of dual-labeled DNA probes encapsulated in vesicles. Through our single-vesicle content mixing assay, we found the fusion pore expansion role of yeast SNAREs as well as neuronal SNAREs plus synaptotagmin 1.
Issue Date:2011-01-21
Rights Information:Copyright 2010 Jiajie Diao
Date Available in IDEALS:2011-01-21
Date Deposited:2010-12

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