Scaffolding viral protein NC nucleates phase separation of the HIV-1 biomolecular condensate

Membraneless biomolecular condensates (BMCs) contribute to the replication of a growing number of viruses but remain to be functionally characterized. Previously, we demonstrated that pan-retroviral nucleocapsid (NC) proteins phase separated into condensates regulating virus assembly. Here we discover that intrinsically disordered human immunodeficiency virus-type 1 (HIV-1) core proteins condense with the viral genomic RNA (vRNA) to assemble as BMCs attaining a geometry characteristic of viral reverse transcription complexes. We explore the predisposition, mechanisms, and pharmacologic sensitivity of HIV-1 core BMCs in living cells. HIV-1 vRNA-interacting NC condensates were found to be scaffolds onto which client capsid, reverse transcriptase, and integrase condensates assemble. HIV-1 core BMCs exhibit fundamental characteristics of BMCs and are drug-sensitive. Lastly, protease-mediated maturation of Gag and Gag-Pol precursor proteins yield abundant and visible BMCs in cells. This study redefines HIV-1 core components as fluid BMCs and advances our understanding of the nature of viral cores during ingress.

Automated summary

This study reveals that HIV-1 core proteins can condense with viral genomic RNA to form membraneless biomolecular condensates (BMCs), and investigates the characteristics and drug sensitivity of these BMCs in living cells. The findings demonstrate that HIV-1 core BMCs exhibit similar features to other biomolecular condensates and can be further formed into visible condensates through protease-mediated maturation, playing a crucial role in the viral ingress process.