Site-Specific Structural Variations Accompanying Tubular Assembly of the HIV-1 Capsid Protein

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• 作者：Marvin J. Bayro ; Bo Chen ; Wai-Ming Yau ; Robert Tycko
• 关键词：HIV-1 ; human immunodeficiency virus type 1 ; NTD ; N-terminal domain ; CTD ; C-terminal domain ; cryoEM ; cryoelectron microscopy ; 2D ; two-dimensional ; 3D ; three-dimensional ; MAS ; magic-angle spinning ; PEG-8000 ; polyethylene glycol 8000 ; TEM ; transmission electron microscopy ; rf ; radiofrequency ; 尾ME ; 尾-mercaptoethanol ; RFDR ; radiofrequency-driven recoupling ; DARR ; dipolar-assisted rotary resonance ; FID ; free-induction decay ; TEDOR ; transferred echo double resonance
• 刊名：Journal of Molecular Biology
• 出版年：6 March, 2014
• 年：2014
• 卷：426
• 期：5
• 页码：1109-1127
• 全文大小：2638 K

文摘

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 尾-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.