@article {49581, title = {MicroED structures of HIV-1 Gag CTD-SP1 reveal binding interactions with the maturation inhibitor bevirimat.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {115}, year = {2018}, month = {2018 Dec 26}, pages = {13258-63}, abstract = {

HIV-1 protease (PR) cleavage of the Gag polyprotein triggers the assembly of mature, infectious particles. Final cleavage of Gag occurs at the junction helix between the capsid protein CA and the SP1 spacer peptide. Here we used MicroED to delineate the binding interactions of the maturation inhibitor bevirimat (BVM) using very thin frozen-hydrated, 3D microcrystals of a CTD-SP1 Gag construct with and without bound BVM. The 2.9-{\r A} MicroED structure revealed that a single BVM molecule stabilizes the six-helix bundle via both electrostatic interactions with the dimethylsuccinyl moiety and hydrophobic interactions with the pentacyclic triterpenoid ring. These results provide insight into the mechanism of action of BVM and related maturation inhibitors that will inform further drug discovery efforts. This study also demonstrates the capabilities of MicroED for structure-based drug design.

}, issn = {1091-6490}, doi = {10.1073/pnas.1806806115}, author = {Purdy, Michael D and Shi, Dan and Chrustowicz, Jakub and Hattne, Johan and Gonen, Tamir and Yeager, Mark} } @article {48939, title = {Immature HIV-1 lattice assembly dynamics are regulated by scaffolding from nucleic acid and the plasma membrane.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {114}, year = {2017}, month = {2017 Nov 07}, pages = {E10056-65}, abstract = {

The packaging and budding of Gag polyprotein and viral RNA is a critical step in the HIV-1 life cycle. High-resolution structures of the Gag polyprotein have revealed that the capsid (CA) and spacer peptide 1 (SP1) domains contain important interfaces for Gag self-assembly. However, the molecular details of the multimerization process, especially in the presence of RNA and the cell membrane, have remained unclear. In this work, we investigate the mechanisms that work in concert between the polyproteins, RNA, and membrane to promote immature lattice growth. We develop a coarse-grained (CG) computational model that is derived from subnanometer resolution structural data. Our simulations recapitulate contiguous and hexameric lattice assembly driven only by weak anisotropic attractions at the helical CA-SP1 junction. Importantly, analysis from CG and single-particle tracking photoactivated localization (spt-PALM) trajectories indicates that viral RNA and the membrane are critical constituents that actively promote Gag multimerization through scaffolding, while overexpression of short competitor RNA can suppress assembly. We also find that the CA amino-terminal domain imparts intrinsic curvature to the Gag lattice. As a consequence, immature lattice growth appears to be coupled to the dynamics of spontaneous membrane deformation. Our findings elucidate a simple network of interactions that regulate the early stages of HIV-1 assembly and budding.

}, issn = {1091-6490}, doi = {10.1073/pnas.1706600114}, author = {Pak, Alexander J and Grime, John M A and Sengupta, Prabuddha and Chen, Antony K and Durumeric, Aleksander E P and Srivastava, Anand and Yeager, Mark and Briggs, John A G and Lippincott-Schwartz, Jennifer and Voth, Gregory A} }