Progress in FY2011 was in the following areas: (1) HIV-1 CAPSID ASSEMBLIES. We have improved our experimental conditions for in vitro HIV-1 CA assembly, resulting in highly uniform and robust tubular assemblies that yield high-resolution solid state NMR spectra. 2D 13C-13C and 15N-13C spectra have been acquired;3D measurements are in progress. It may prove possible to determine full chemical shift assignments for full-length, wild-type HIV-1 CA assemblies, providing new information about intermolecular interactions, local dynamics, and structural variations that underlie pentamer/hexamer equilibria and assembly curvature. In addition, we have completed and published Monte Carlo simulation studies that show for the first time how a hexagonal lattice of HIV-1 CA develops from an initial state of soluble CA dimers. (2) DETERMINATION OF HELICAL BUNDLE STRUCTURES FOR HIV-1 VPU. We have completed and published a series of solid state NMR measurements on the transmembrane domain of the Vpu protein, which is capable of forming oligomeric ion channels that may be related to Vpu's role in viral budding. Our data provide constraints on the supramolecular structure of symmetric helical bundles that may represent the ion channel-active state of Vpu. Solid state NMR measurements have been supplemented by photochemical crosslinking and analytical ultracentrifugation studies to determine the oligomerization number. Although our data indicate a diversity of oligomerization states for Vpu in phospholipid bilayers, the predominant oligomer appears to be a pentamer. We have developed specific models that are consistent with existing data through computational modeling and energy minimization.

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Gupta, Sebanti; Tycko, Robert (2018) Segmental isotopic labeling of HIV-1 capsid protein assemblies for solid state NMR. J Biomol NMR 70:103-114
Bayro, Marvin J; Ganser-Pornillos, Barbie K; Zadrozny, Kaneil K et al. (2016) Helical Conformation in the CA-SP1 Junction of the Immature HIV-1 Lattice Determined from Solid-State NMR of Virus-like Particles. J Am Chem Soc 138:12029-32
Bayro, Marvin J; Tycko, Robert (2016) Structure of the Dimerization Interface in the Mature HIV-1 Capsid Protein Lattice from Solid State NMR of Tubular Assemblies. J Am Chem Soc 138:8538-46
Lu, Jun-Xia; Bayro, Marvin J; Tycko, Robert (2016) Major Variations in HIV-1 Capsid Assembly Morphologies Involve Minor Variations in Molecular Structures of Structurally Ordered Protein Segments. J Biol Chem 291:13098-112
Bayro, Marvin J; Chen, Bo; Yau, Wai-Ming et al. (2014) Site-specific structural variations accompanying tubular assembly of the HIV-1 capsid protein. J Mol Biol 426:1109-27
Chen, Bo; Tycko, Robert (2011) Simulated self-assembly of the HIV-1 capsid: protein shape and native contacts are sufficient for two-dimensional lattice formation. Biophys J 100:3035-44
Lu, Jun-Xia; Sharpe, Simon; Ghirlando, Rodolfo et al. (2010) Oligomerization state and supramolecular structure of the HIV-1 Vpu protein transmembrane segment in phospholipid bilayers. Protein Sci :
Chen, Bo; Tycko, Robert (2010) Structural and dynamical characterization of tubular HIV-1 capsid protein assemblies by solid state nuclear magnetic resonance and electron microscopy. Protein Sci 19:716-30