Non-nucleoside inhibitors of human immunodeficiency virus type 1 reverse transcriptase (RT), NNRTIs, which bind to the p66/p51 heterodimeric RT, also interact with the p66/p66 homodimer, whose structure is unknown. F nuclear magnetic resonance of a single 4-trifluoromethylphenylalanine (tfmF) residue, incorporated into the NNRTI binding pocket of the p66/p66 homodimer at position 181, was used to investigate NNRTI binding. In the NNRTI-bound homodimer complex, two different F signals are observed, with the resonance frequencies matching those of the NNRTI-bound p66/p51 heterodimer spectra, in which the individual p66-subunit or p51-subunit were labeled with tfmF at positions 181. These data suggest that the NNRTI-bound p66/p66 homodimer conformation, particularly around residue 181, is very similar to that in the p66/p51 heterodimer, explaining why NNRTI binding to p66/p66 enhances dimer formation.
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http://dx.doi.org/10.1002/prot.25383 | DOI Listing |
Protein Sci
July 2024
Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
The Gag-Pol polyprotein in human immunodeficiency virus type I (HIV-1) encodes enzymes that are essential for virus replication: protease (PR), reverse transcriptase (RT), and integrase (IN). The mature forms of PR, RT and IN are homodimer, heterodimer and tetramer, respectively. The precise mechanism underlying the formation of dimer or tetramer is not yet understood.
View Article and Find Full Text PDFBiomolecules
November 2023
Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, Durham, NC 27709, USA.
Formation of active HIV-1 reverse transcriptase (RT) proceeds via a structural maturation process that involves subdomain rearrangements and formation of an asymmetric p66/p66' homodimer. These studies were undertaken to evaluate whether the information about this maturation process can be used to identify small molecule ligands that retard or interfere with the steps involved. We utilized the isolated polymerase domain, p51, rather than p66, since the initial subdomain rearrangements are largely limited to this domain.
View Article and Find Full Text PDFInt J Mol Sci
December 2020
Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
NMR studies of large proteins, over 100 kDa, in solution are technically challenging and, therefore, of considerable interest in the biophysics field. The challenge arises because the molecular tumbling of a protein in solution considerably slows as molecular mass increases, reducing the ability to detect resonances. In fact, the typical H-C or H-N correlation spectrum of a large protein, using a C- or N-uniformly labeled protein, shows severe line-broadening and signal overlap.
View Article and Find Full Text PDFChembiochem
November 2020
Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 5, Room B1-30I, 5 Medical Center Drive, Bethesda, MD 20892-0520, USA.
Following excision from the Gag-Pol polyprotein, HIV-1 reverse transcriptase is released as an asymmetric homodimer comprising two p66 subunits that are structurally dissimilar but identical in amino acid sequence. Subsequent cleavage of the RNase H domain from only one of the subunits, denoted p66', results in the formation of the mature p66/p51 enzyme in which catalytic activity resides in the p66 subunit, and the p51 subunit (derived from p66') provides a supporting structural scaffold. Here, we probe the interaction of the p66/p66' asymmetric reverse transcriptase precursor with HIV-1 protease by pulsed Q-band double electron-electron resonance EPR spectroscopy to measure distances between nitroxide labels introduced at surface-engineered cysteine residues.
View Article and Find Full Text PDFProteins
December 2017
Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15260.
Non-nucleoside inhibitors of human immunodeficiency virus type 1 reverse transcriptase (RT), NNRTIs, which bind to the p66/p51 heterodimeric RT, also interact with the p66/p66 homodimer, whose structure is unknown. F nuclear magnetic resonance of a single 4-trifluoromethylphenylalanine (tfmF) residue, incorporated into the NNRTI binding pocket of the p66/p66 homodimer at position 181, was used to investigate NNRTI binding. In the NNRTI-bound homodimer complex, two different F signals are observed, with the resonance frequencies matching those of the NNRTI-bound p66/p51 heterodimer spectra, in which the individual p66-subunit or p51-subunit were labeled with tfmF at positions 181.
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