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Dissertation
Structural basis of HIV-1 GP120 dual receptor site antagonism by peptide triazoles
Doctor of Philosophy (Ph.D.), Drexel University
Aug 2012
DOI:
https://doi.org/10.17918/00008342
Abstract
Acquired Immune Deficiency Syndrome (AIDS) is a lethal disease that can only be controlled with life-long treatment with anti-retroviral drugs. AIDS is caused by infection with the Human Immunodeficiency Virus 1 (HIV-1) and eventual depletion of helper T-cells and the immune system. New antiretroviral regimens are needed in treatment of HIV-1 infection as multi-drug resistance continues to plague current treatments. The entry step of HIV has been an elusive target due to conformational masking of neutralization sites on the viral envelope proteins gp120 and gp41. Currently, two entry inhibitors are approved only for treatment-experienced patients due to potential for tropism switch, viral resistance and lack of improvement over current regimens. Dual antagonist peptide triazoles (PT) are a novel class of gp120 antagonist peptides that inhibit interactions of gp120 with both its primary receptor CD4 and its co-receptor CCR5 or CXCR4. In order to determine their mode of action, we converted multiple residues at and near a putative peptide binding site to alanine and screened them for induced effects on PT binding and inhibition. Selected mutants that varied by an order of magnitude or more from WT were purified and also expressed in virus, and tested for their effects on direct binding and inhibition by the PT KR21. The results defined a new, putative PT binding site overlapping with that of CD4. We further investigated the use of the CD4 binding site by PTs and overall found alternate use of residues in this site by the PT vs. CD4. We also observed that PT binding resulted in multiple conformation-sensitive antibody epitopes being inaccessible, including epitopes that are enhanced by CD4 and/or lie outside the PT hot-spot. These results argue for an alternative use of the CD4 binding site and allosteric inhibition of gp120 that results from it, and support the proposed PT binding site as all epitopes that overlapped with this site were inhibited, while linear epitopes that did not overlap were not affected. A structurally defined antibody paratope with extensive contacts to all PT site residues suggests a mode of binding and inhibition by the PTs.
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Details
- Title
- Structural basis of HIV-1 GP120 dual receptor site antagonism by peptide triazoles
- Creators
- Sinan Ferit Tuzer
- Contributors
- Irwin Chaiken (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xii, 162 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 991021889074504721