title: Conformational Plasticity of the NNRTI-Binding Pocket in HIV-1 Reverse Transcriptase: A Fluorine Nuclear Magnetic Resonance Study.
abstract: HIV-1 reverse transcriptase (RT) is a major drug target in the treatment of HIV-1 infection. RT inhibitors currently in use include non-nucleoside, allosteric RT inhibitors (NNRTIs), which bind to a hydrophobic pocket, distinct from the enzyme's active site. We investigated RT-NNRTI interactions by solution (19)F nuclear magnetic resonance (NMR), using singly (19)F-labeled RT proteins. Comparison of (19)F chemical shifts of fluorinated RT and drug-resistant variants revealed that the fluorine resonance is a sensitive probe for identifying mutation-induced changes in the enzyme. Our data show that in the unliganded enzyme, the NNRTI-binding pocket is highly plastic and not locked into a single conformation. Upon inhibitor binding, the binding pocket becomes rigidified. In the inhibitor-bound state, the (19)F signal of RT is similar to that of drug-resistant mutant enzymes, distinct from what is observed for the free state. Our results demonstrate the power of (19)F NMR spectroscopy to characterize conformational properties using selectively (19)F-labeled protein.
authors.affiliation: Department of Structural Biology and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Naima G
authors.initials: NG
authors.lastname: Sharaf
authors.affiliation: Department of Structural Biology and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Rieko
authors.initials: R
authors.lastname: Ishima
authors.affiliation: Department of Structural Biology and Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gronenborn
mesh_terms: D020134:Catalytic Domain; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D018894:Reverse Transcriptase Inhibitors / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D018894:Reverse Transcriptase Inhibitors; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase