Targeting a Dark Excited State of HIV‐1 Nucleocapsid by Antiretroviral Thioesters Revealed by NMR Spectroscopy |
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| Authors: | Dr. Lalit Deshmukh Dr. Vitali Tugarinov Dr. Daniel H. Appella Dr. G. Marius Clore |
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| Affiliation: | 1. Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA;2. Present address: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA;3. Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA |
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| Abstract: | HIV‐1 nucleocapsid (NCp7) is a two Cys2HisCys zinc knuckle (N‐Zn and C‐Zn) protein that plays a key role in viral replication. NCp7 conformational dynamics is characterized by NMR relaxation dispersion and chemical exchange saturation transfer measurements. While the N‐Zn knuckle is conformationally stable, the C‐Zn knuckle interconverts on the millisecond timescale between the major state, in which the zinc is coordinated by three cysteines and a histidine, and two folded minor species (with populations around 1 %) in which one of the coordination bonds (Cys413‐Sγ‐Zn or His421‐N?2‐Zn) is hydrolyzed. These findings explain why antiretroviral thioesters specifically disrupt the C‐Zn knuckle by initial acylation of Cys413, and show that transient, sparsely‐populated (“dark”), excited states of proteins can present effective targets for rational drug design. |
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| Keywords: | antiretrovirals conformational exchange HIV-1 nucleocapsid relaxation dispersion zinc |
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