Influence of HIV-1 Genomic RNA on the Formation of Gag Biomolecular Condensates |
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Affiliation: | 1. Lady Davis Institute at the Jewish General Hospital, Montréal, Québec H3T 1E2, Canada;2. Department of Medicine, Pennsylvania State University College of Medicine, Hershey, PA 17033, United States;3. Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA 17033, United States;4. Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada;5. Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey, PA 17033, United States;6. Department of Medicine, McGill University, Montréal, Québec H4A 3J1, Canada |
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Abstract: | Biomolecular condensates (BMCs) play an important role in the replication of a growing number of viruses, but many important mechanistic details remain to be elucidated. Previously, we demonstrated that the pan-retroviral nucleocapsid (NC) and HIV-1 pr55Gag (Gag) proteins phase separate into condensates, and that HIV-1 protease (PR)-mediated maturation of Gag and Gag-Pol precursor proteins yields self-assembling BMCs that have HIV-1 core architecture. Using biochemical and imaging techniques, we aimed to further characterize the phase separation of HIV-1 Gag by determining which of its intrinsically disordered regions (IDRs) influence the formation of BMCs, and how the HIV-1 viral genomic RNA (gRNA) could influence BMC abundance and size. We found that mutations in the Gag matrix (MA) domain or the NC zinc finger motifs altered condensate number and size in a salt-dependent manner. Gag BMCs were also bimodally influenced by the gRNA, with a condensate-promoting regime at lower protein concentrations and a gel dissolution at higher protein concentrations. Interestingly, incubation of Gag with CD4+ T cell nuclear lysates led to the formation of larger BMCs compared to much smaller ones observed in the presence of cytoplasmic lysates. These findings suggest that the composition and properties of Gag-containing BMCs may be altered by differential association of host factors in nuclear and cytosolic compartments during virus assembly. This study significantly advances our understanding of HIV-1 Gag BMC formation and provides a foundation for future therapeutic targeting of virion assembly. |
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Keywords: | human immunodeficiency virus-type 1 biomolecular condensates gag polyprotein viral genomic RNA phase diagrams |
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