@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 = {<p>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.</p>
},
	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}
}
@article {47627,
	title = {MicroRNA binding to the HIV-1 Gag protein inhibits Gag assembly and virus production.},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {111},
	year = {2014},
	month = {2014 Jul 1},
	pages = {E2676-83},
	abstract = {<p>MicroRNAs (miRNAs) are small, 18-22 nt long, noncoding RNAs that act as potent negative gene regulators in a variety of physiological and pathological processes. To repress gene expression, miRNAs are packaged into RNA-induced silencing complexes (RISCs) that target mRNAs for degradation and/or translational repression in a sequence-specific manner. Recently, miRNAs have been shown to also interact with proteins outside RISCs, impacting cellular processes through mechanisms not involving gene silencing. Here, we define a previously unappreciated activity of miRNAs in inhibiting RNA-protein interactions that in the context of HIV-1 biology blocks HIV virus budding and reduces virus infectivity. This occurs by miRNA binding to the nucleocapsid domain of the Gag protein, the main structural component of HIV-1 virions. The resulting miRNA-Gag complexes interfere with viral-RNA-mediated Gag assembly and viral budding at the plasma membrane, with imperfectly assembled Gag complexes endocytosed and delivered to lysosomes. The blockade of virus production by miRNA is reversed by adding the miRNA{\textquoteright}s target mRNA and stimulated by depleting Argonaute-2, suggesting that when miRNAs are not mediating gene silencing, they can block HIV-1 production through disruption of Gag assembly on membranes. Overall, our findings have significant implications for understanding how cells modulate HIV-1 infection by miRNA expression and raise the possibility that miRNAs can function to disrupt RNA-mediated protein assembly processes in other cellular contexts.</p>
},
	keywords = {Argonaute Proteins, Cluster Analysis, DNA Primers, HEK293 Cells, HIV-1, Humans, MicroRNAs, Microscopy, Fluorescence, Multiprotein Complexes, Protein Precursors, RNA, Small Interfering, Virus Assembly, Virus Release},
	issn = {1091-6490},
	doi = {10.1073/pnas.1408037111},
	author = {Chen, Antony K and Sengupta, Prabuddha and Waki, Kayoko and Van Engelenburg, Schuyler B and Ochiya, Takahiro and Ablan, Sherimay D and Freed, Eric O and Lippincott-Schwartz, Jennifer}
}
