Title
Site-specific structural variations accompanying tubular assembly of the hiv-1 capsid protein
Date Issued
06 March 2014
Access level
open access
Resource Type
research article
Author(s)
Chen B.
Yau W.M.
Tycko R.
National Institutes of Health
Abstract
The 231-residue capsid (CA) protein of human immunodeficiency virus type 1 (HIV-1) spontaneously self-assembles into tubes with a hexagonal lattice that is believed to mimic the surface lattice of conical capsid cores within intact virions. We report the results of solid-state nuclear magnetic resonance (NMR) measurements on HIV-1 CA tubes that provide new information regarding changes in molecular structure that accompany CA self-assembly, local dynamics within CA tubes, and possible mechanisms for the generation of lattice curvature. This information is contained in site-specific assignments of signals in two- and three-dimensional solid-state NMR spectra, conformation-dependent 15N and 13C NMR chemical shifts, detection of highly dynamic residues under solution NMR conditions, measurements of local variations in transverse spin relaxation rates of amide 1H nuclei, and quantitative measurements of site-specific 15N-15N dipole-dipole couplings. Our data show that most of the CA sequence is conformationally ordered and relatively rigid in tubular assemblies and that structures of the N-terminal domain (NTD) and the C-terminal domain (CTD) observed in solution are largely retained. However, specific segments, including the N-terminal β-hairpin, the cyclophilin A binding loop, the inter-domain linker, segments involved in intermolecular NTD-CTD interactions, and the C-terminal tail, have substantial static or dynamical disorder in tubular assemblies. Other segments, including the 310-helical segment in CTD, undergo clear conformational changes. Structural variations associated with curvature of the CA lattice appear to be localized in the inter-domain linker and intermolecular NTD-CTD interface, while structural variations within NTD hexamers, around local 3-fold symmetry axes, and in CTD-CTD dimerization interfaces are less significant.
Start page
1109
End page
1127
Volume
426
Issue
5
Language
English
OCDE Knowledge area
Bioquímica, Biología molecular
Scopus EID
2-s2.0-84894066520
PubMed ID
Source
Journal of Molecular Biology
ISSN of the container
00222836
Sponsor(s)
Residues that are partially mobile, revealed by the 1 H T 2 -filtered NCA spectra ( Fig. 4 and Table S5), are limited to interhelical segments, especially the cyclophilin A binding loop between H4 and H5. Mobility of the cyclophilin A binding loop is supported by the absence of detectable solid-state NMR signals from residues 96–97. Thus, the cyclophilin A binding loop is dynamic in CA tubes but not so dynamic (or disordered) that signals from residues 84–95 are absent from solid-state NMR spectra, as most of these residues have unambiguous signal assignments.
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