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Strain and rupture of HIV-1 capsids during uncoating.

ABSTRACT: SignificanceThe mature capsids of HIV-1 are transiently stable complexes that self-assemble around the viral genome during maturation, and uncoat to release preintegration complexes that archive a double-stranded DNA copy of the virus in the host cell genome. However, a detailed view of how HIV cores rupture remains lacking. Here, we elucidate the physical properties involved in capsid rupture using a combination of large-scale all-atom molecular dynamics simulations and cryo-electron tomography. We find that intrinsic strain on the capsid forms highly correlated patterns along the capsid surface, along which cracks propagate. Capsid rigidity also increases with high strain. Our findings provide fundamental insight into viral capsid uncoating.

SUBMITTER: Yu A

PROVIDER: S-EPMC8915963 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature

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Strain and rupture of HIV-1 capsids during uncoating.

Yu Alvin A Lee Elizabeth M Y EMY Briggs John A G JAG Ganser-Pornillos Barbie K BK Pornillos Owen O Voth Gregory A GA

Proceedings of the National Academy of Sciences of the United States of America 20220301 10

SignificanceThe mature capsids of HIV-1 are transiently stable complexes that self-assemble around the viral genome during maturation, and uncoat to release preintegration complexes that archive a double-stranded DNA copy of the virus in the host cell genome. However, a detailed view of how HIV cores rupture remains lacking. Here, we elucidate the physical properties involved in capsid rupture using a combination of large-scale all-atom molecular dynamics simulations and cryo-electron tomography ...[more]

PMID: 35238630

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Project description:The ability of human immunodeficiency virus type 1 (HIV-1) to transduce nondividing cells is key to infecting terminally differentiated macrophages, which can serve as a long-term reservoir of HIV-1 infection. The mutation N57A in the viral CA protein renders HIV-1 cell cycle dependent, allowing examination of HIV-1 infection of nondividing cells. Here, we show that the N57A mutation confers a postentry infectivity defect that significantly differs in magnitude between the common lab-adapted molecular clones HIV-1NL4-3 (>10-fold) and HIV-1LAI (2- to 5-fold) in multiple human cell lines and primary CD4+ T cells. Capsid permeabilization and reverse transcription are altered when N57A is incorporated into HIV-1NL4-3 but not HIV-1LAI The N57A infectivity defect is significantly exacerbated in both virus strains in the presence of cyclosporine (CsA), indicating that N57A infectivity is dependent upon CA interacting with host factor cyclophilin A (CypA). Adaptation of N57A HIV-1LAI selected for a second CA mutation, G94D, which rescued the N57A infectivity defect in HIV-1LAI but not HIV-1NL4-3 The rescue of N57A by G94D in HIV-1LAI is abrogated by CsA treatment in some cell types, demonstrating that this rescue is CypA dependent. An examination of over 40,000 HIV-1 CA sequences revealed that the four amino acids that differ between HIV-1NL4-3 and HIV-1LAI CA are polymorphic, and the residues at these positions in the two strains are widely prevalent in clinical isolates. Overall, a few polymorphic amino acid differences between two closely related HIV-1 molecular clones affect the phenotype of capsid mutants in different cell types.IMPORTANCE The specific mechanisms by which HIV-1 infects nondividing cells are unclear. A mutation in the HIV-1 capsid protein abolishes the ability of the virus to infect nondividing cells, serving as a tool to examine cell cycle dependence of HIV-1 infection. We have shown that two widely used HIV-1 molecular clones exhibit significantly different N57A infectivity phenotypes due to fewer than a handful of CA amino acid differences and that these clones are both represented in HIV-infected individuals. As such minor differences in closely related HIV-1 strains may impart significant infectivity differences, careful consideration should be given to drawing conclusions from one particular HIV-1 clone. This study highlights the potential for significant variation in results with the use of multiple strains and possible unanticipated effects of natural polymorphisms.

Project description:UnlabelledFollowing entry into the target cell, human immunodeficiency virus type 1 (HIV-1) must reverse transcribe its RNA genome to DNA and traffic to the nuclear envelope, where the viral genome is translocated into the nucleus for subsequent integration into the host cell chromosome. During this time, the viral core, which houses the genome, undergoes a poorly understood process of disassembly, known as uncoating. Collectively, many studies suggest that uncoating is tightly regulated to allow nuclear import of the genome while minimizing the exposure of the newly synthesized DNA to cytosolic DNA sensors. However, whether host cellular proteins facilitate this process remains poorly understood. Here we report that intact microtubules facilitate HIV-1 uncoating in target cells. Disruption of microtubules with nocodazole substantially delays HIV-1 uncoating, as revealed with three different assay systems. This defect in uncoating did not correlate with defective reverse transcription at early times postinfection, demonstrating that microtubule-facilitated uncoating is distinct from the previously reported role of viral reverse transcription in the uncoating process. We also find that pharmacological or small interfering RNA (siRNA)-mediated inhibition of cytoplasmic dynein or the kinesin 1 heavy chain KIF5B delays uncoating, providing detailed insight into how microtubules facilitate the uncoating process. These studies reveal a previously unappreciated role for microtubules and microtubule motor function in HIV-1 uncoating, establishing a functional link between viral trafficking and uncoating. Targeted disruption of the capsid motor interaction may reveal novel mechanisms of inhibition of viral infection or provide opportunities to activate cytoplasmic antiviral responses directed against capsid or viral DNA.ImportanceDuring HIV-1 infection, fusion of viral and target cell membranes dispenses the viral ribonucleoprotein complex into the cytoplasm of target cells. During this time, the virus must reverse transcribe its RNA genome, traffic from the location of fusion to the nuclear membrane, and undergo the process of uncoating, whereby the viral capsid core disassembles to allow the subsequent nuclear import of the viral genome. Numerous cellular restriction factors target the viral capsid, suggesting that perturbation of the uncoating process represents an excellent antiviral target. However, this uncoating process, and the cellular factors that facilitate uncoating, remains poorly understood. The main observation of this study is that normal uncoating requires intact microtubules and is facilitated by dynein and kinesin motors. Targeting these factors may either directly inhibit infection or delay it enough to trigger mediators of intrinsic immunity that recognize cytoplasmic capsid or DNA and subsequently induce an antiviral state in these cells.

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Strain and rupture of HIV-1 capsids during uncoating.

Publications

Strain and rupture of HIV-1 capsids during uncoating.

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