Solid state NMR studies of structure and dynamics of membrane associated influenza fusion peptide
"This work seeks to delineate the role of influenza fusion peptide in the process of membrane fusion. Influenza fusion peptide is represented by the 203033 N-terminal residues of the HA2 subunit of the hemagglutinin (HA) protein. The influenza fusion peptide plays an important role in the membrane fusion between the host viral and the host cell endosomal membrane and has pH dependence. The influenza fusion peptide is the most conserved sequence in the in the influenza genome such that a modest mutation can arrest the fusion activity. It was shown that in detergents the structure of the 20 residue and the 23 residue influenza fusion peptide have different structures. However, influenza fusion peptide is a membrane peptide and induces fusion the lipid vesicles and not between the detergent micelles. In this work, solid state NMR was used to study the structure of the influenza fusion peptide in membranes and its correlation to the vesicle fusion. The influenza peptide was chemically synthesized chemically and was used as a model system to study the membrane fusion process. In PC:PG membranes, the influenza fusion peptide adopts closed and semiclosed structure. Both the closed and the semiclosed structure have a helix/turn/helix structure with an interhelical angle of 1030358° and 1403036° respectively. Unlike detergents, the structures of the 20 residue and the 23 residue are very similar in membranes with some minor differences. At low pH or the fusogenic pH, there is a higher fraction of the semiclosed fraction for both the influenza peptide constructs. For the longer peptide, higher fractions of the closed structures were determined. Vesicle fusion assays served as a surrogate for the virus/endosome fusion. Our data supported a iii strong positive correlation between the vesicle fusion and the hydrophobic surface area. Based on these data we proposed that the hydrophobic interaction between HAfp and the membrane is an important factor in HAfp-catalyzed fusion. Solid state NMR has been applied to study the structure and dynamics of lipid molecules in membrane with fusion peptide but the solid-state NMR data are typically the sum over all lipid molecules with only a small fraction of these molecules next to the fusion peptide. My second project primarily utilized 2 H NMR to study the dynamics of the influenza fusion peptide in membranes. This work describes the development and application of the cross polarization with solid or quadrupolar echo. The main idea of the work is to probe the motions of the lipids adjacent/close to the peptide. This method is applied to two different peptides, HIV-fusion peptide and influenza fusion peptide in presence of membranes. By comparing the conventional solid-echo experiment and the newly developed cross polarization with quadrupolar echo, I have seen differences in the lipid dynamics."--Pages ii-iii.
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- In Collections
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Electronic Theses & Dissertations
- Copyright Status
- In Copyright
- Material Type
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Theses
- Authors
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Ghosh, Ujjayini
- Thesis Advisors
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Weliky, David P.
- Committee Members
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McCracken, John L.
Cukier, Robert I.
Jones, A Daniel
- Date
- 2016
- Program of Study
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Chemistry - Doctor of Philosophy
- Degree Level
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Doctoral
- Language
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English
- Pages
- xvii, 287 pages
- ISBN
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9781369351835
1369351836