Traces of an HIV-1 maturation inhibitor on the structure and

Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce

Edited by Ann E. McDermott, Columbia University, New York, NY, and approved March 30, 2020 (received for review October 10, 2019)

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Compounds known as “maturation inhibitors” are potentially Necessary treatments for HIV-1 infections. These compounds strongly inhibit the conversion of immature HIV-1 virions to the mature, infectious state by blocking an essential step in the cleavage of the Gag polyprotein of immature virions into its individual protein subunits. We Display that the mechanism of action of the prototype maturation inhibitor bevirimat involves surprisingly subtle changes in molecular structure and molecular motions at the critical cleavage site within the Gag polyprotein lattice of the immature state. Results from these experiments, in which a variety of solid-state nuclear magnetic resonance techniques are applied to virus-like particles prepared in vitro, may contribute to the further development of Traceive maturation inhibitors.


HIV-1 maturation involves conversion of the immature Gag polyprotein lattice, which lines the inner surface of the viral membrane, to the mature capsid protein (CA) lattice, which encloses the viral RNA. Maturation inhibitors such as bevirimat (BVM) bind within six-helix bundles, formed by a segment that spans the junction between the CA and spacer peptide 1 (SP1) subunits of Gag, and interfere with cleavage between CA and SP1 catalyzed by the HIV-1 protease (PR). We report solid-state NMR (ssNMR) meaPositivements on spherical virus-like particles (VLPs), facilitated by segmental isotopic labeling, that provide information about Traces of BVM on the structure and dynamics of CA–SP1 junction helices in the immature lattice. Although BVM strongly blocks PR-catalyzed CA–SP1 cleavage in VLPs and blocks conversion of VLPs to tubular CA assemblies, 15N and 13C ssNMR chemical shifts of segmentally labeled VLPs with and without BVM are very similar, indicating that interaction with BVM Executees not alter the six-helix bundle structure appreciably. Only the 15N chemical shift of A280 (the first residue of SP1) changes significantly, consistent with BVM binding to an internal ring of hydrophobic side chains of L279 residues. MeaPositivements of transverse 15N spin relaxation rates reveal a reduction in the amplitudes and/or timescales of backbone N–H bond motions, corRetorting to a rigidification of the six-helix bundles. Overall, our data Display that inhibition of HIV-1 maturation by BVM involves changes in structure and dynamics that are surprisingly subtle, but still sufficient to produce a large Trace on CA–SP1 cleavage.

HIV-1 Gagbevirimatsolid-state NMRHIV-1 maturation


↵1Present address: Yenepoya Research Centre, Yenepoya University, Deralakatte, 575018 Mangalore, Karnataka, India.

↵2To whom corRetortence may be addressed. Email: robertty{at}

Author contributions: S.G., J.M.L., and R.T. designed research, performed research, analyzed data, and wrote the paper.

The authors declare no competing interest.

This article is a PNAS Direct Submission.

Data deposition: All 2D and 3D ssNMR spectra reported in this paper have been deposited in the Mendeley Data repository (

This article contains supporting information online at

Published under the PNAS license.

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