Role of Host Proteins in HIV-1 Early Replication

The human immunodeficiency virus (HIV-1 virus) exploits several host factors for assembly, infection, and replication within the infected cells. In this work, we describe the evidence for an interaction of the N-terminal domain of the HIV-1 capsid protein with human calmodulin. The precise role of this interaction within the life cycle of the HIV-1 virus is yet to be defined. Potential roles for this interaction in the viral capsid uncoating are discussed.

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Cellular and Biochemical Mechanisms of the Retroviral Restriction Factor SAMHD1

ISRN Biochemistry ◽

10.1155/2013/728392 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 13

Author(s):

Li Wu

Keyword(s):

Host Protein ◽

Nucleic Acid Metabolism ◽

Target Cells ◽

Restriction Factors ◽

Host Proteins ◽

Retroviral Infection ◽

Deoxynucleoside Triphosphate ◽

Biochemical Mechanisms ◽

Hiv 1

Replication of HIV-1 and other retroviruses is dependent on numerous host proteins in the cells. Some of the host proteins, however, function as restriction factors to block retroviral infection of target cells. The host protein SAMHD1 has been identified as the first mammalian deoxynucleoside triphosphate triphosphohydrolase (dNTPase), which blocks the infection of HIV-1 and other retroviruses in non-cycling immune cells. SAMHD1 protein is highly expressed in human myeloid-lineage cells and CD4+ T-lymphocytes, but its retroviral restriction function is only observed in noncycling cells. Recent studies have revealed biochemical mechanisms of SAMHD1-mediated retroviral restriction. In this review, the latest progress on SAMHD1 research is summarized and the mechanisms by which SAMHD1 mediates retroviral restriction are analyzed. Although the physiological function of SAMHD1 is largely unknown, this review provides perspectives about the role of endogenous SAMHD1 protein in maintaining normal cellular function, such as nucleic acid metabolism and the proliferation of cells.

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HIV Assembly and Budding: Ca2+ Signaling and Non-ESCRT Proteins Set the Stage

Molecular Biology International ◽

10.1155/2012/851670 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 9

Author(s):

Lorna S. Ehrlich ◽

Carol A. Carter

Keyword(s):

Protein Trafficking ◽

Endocytic Pathway ◽

Host Proteins ◽

Virus Budding ◽

Endosomal Sorting ◽

The Past ◽

Escrt Machinery ◽

Cellular Factors ◽

Hiv 1

More than a decade has elapsed since the link between the endosomal sorting complex required for transport (ESCRT) machinery and HIV-1 protein trafficking and budding was first identified. L domains in HIV-1 Gag mediate recruitment of ESCRT which function in bud abscission releasing the viral particle from the host cell. Beyond virus budding, the ESCRT machinery is also involved in the endocytic pathway, cytokinesis, and autophagy. In the past few years, the number of non-ESCRT host proteins shown to be required in the assembly process has also grown. In this paper, we highlight the role of recently identified cellular factors that link ESCRT machinery to calcium signaling machinery and we suggest that this liaison contributes to setting the stage for productive ESCRT recruitment and mediation of abscission. Parallel paradigms for non-ESCRT roles in virus budding and cytokinesis will be discussed.

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The Vpu-interacting protein ATP6V0C regulates expression of tetherin and HIV-1 release

10.1101/2020.03.01.972125 ◽

2020 ◽

Author(s):

Abdul A. Waheed ◽

Maya Swiderski ◽

Ali Khan ◽

Ariana Gitzen ◽

Ahlam Majadly ◽

...

Keyword(s):

Surface Expression ◽

Vacuolar Atpase ◽

Cell Surface Expression ◽

Host Proteins ◽

Interacting Protein ◽

Host Restriction ◽

Host Restriction Factor ◽

Tetherin Expression ◽

Hiv 1

AbstractThe HIV-1 accessory protein Vpu enhances virus release by down-regulating cell surface expression of the host restriction factor tetherin. To further understand the role of host proteins in Vpu function, we carried out yeast two-hybrid screening and identified the V0 subunit C of vacuolar ATPase (ATP6V0C) as a Vpu-binding protein. To examine the role of ATP6V0C in Vpu-mediated tetherin degradation and HIV-1 release, we knocked down ATP6V0C expression in HeLa cells and observed that ATP6V0C depletion impairs Vpu-mediated tetherin degradation, resulting in a defect in HIV-1 release. We also observed that overexpression of ATP6V0C stabilizes tetherin expression. This stabilization is specific to ATP6V0C, as overexpression of another subunit of the vacuolar ATPase, ATP6V0C”, had no effect on tetherin expression. ATP6V0C overexpression did not stabilize CD4, another target of Vpu-mediated degradation. Immunofluorescence localization studies showed that the ATP6V0C-stabilized tetherin is sequestered in a CD63- and LAMP1-positive intracellular compartment. These data demonstrate that the Vpu-interacting protein ATP6V0C plays a role in regulating tetherin expression and HIV-1 assembly and release.

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The viral protein U (Vpu)-interacting host protein ATP6V0C down-regulates cell-surface expression of tetherin and thereby contributes to HIV-1 release

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.013280 ◽

2020 ◽

Vol 295 (21) ◽

pp. 7327-7340

Author(s):

Abdul A. Waheed ◽

Maya Swiderski ◽

Ali Khan ◽

Ariana Gitzen ◽

Ahlam Majadly ◽

...

Keyword(s):

Cell Surface ◽

Viral Protein ◽

Surface Expression ◽

Vacuolar Atpase ◽

Cell Surface Expression ◽

Host Proteins ◽

Viral Protein U ◽

Tetherin Expression ◽

Hiv 1

Host proteins with antiviral activity have evolved as first-line defenses to suppress viral replication. The HIV-1 accessory protein viral protein U (Vpu) enhances release of the virus from host cells by down-regulating the cell-surface expression of the host restriction factor tetherin. However, the exact mechanism of Vpu-mediated suppression of antiviral host responses is unclear. To further understand the role of host proteins in Vpu's function, here we carried out yeast two-hybrid screening and identified the V0 subunit C of vacuolar ATPase (ATP6V0C) as a Vpu-binding protein. To examine the role of ATP6V0C in Vpu-mediated tetherin degradation and HIV-1 release, we knocked down ATP6V0C expression in HeLa cells and observed that ATP6V0C depletion impairs Vpu-mediated tetherin degradation, resulting in defective HIV-1 release. We also observed that ATP6V0C overexpression stabilizes tetherin expression. This stabilization effect was specific to ATP6V0C, as overexpression of another subunit of the vacuolar ATPase, ATP6V0C″, had no effect on tetherin expression. ATP6V0C overexpression did not stabilize CD4, another target of Vpu-mediated degradation. Immunofluorescence localization experiments revealed that the ATP6V0C-stabilized tetherin is sequestered in a CD63– and lysosome-associated membrane protein 1 (LAMP1)–positive intracellular compartment. These results indicate that the Vpu-interacting protein ATP6V0C plays a role in down-regulating cell-surface expression of tetherin and thereby contributes to HIV-1 assembly and release.

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HIV-1 Gag recruits oligomeric Vpr via two binding sites in p6, but both mature p6 and Vpr are rapidly lost upon target cell entry

Journal of Virology ◽

10.1128/jvi.00554-21 ◽

2021 ◽

Author(s):

Madushi Wanaguru ◽

Kate N. Bishop

Keyword(s):

Viral Replication ◽

Target Cell ◽

Binding Sites ◽

Cell Entry ◽

Target Cells ◽

Accessory Protein ◽

Virus Budding ◽

Early Replication ◽

Hiv 1

The p12 region of MLV Gag and the p6 region of HIV-1 Gag contain late-domains required for virus budding. Additionally, the accessory protein Vpr is recruited into HIV particles via p6. Mature p12 is essential for early viral replication events, but the role of mature p6 in early replication is unknown. Using a proviral vector in which the gag and pol reading frames are uncoupled, we have performed the first alanine-scanning mutagenesis screens across p6, to probe its importance for early HIV-1 replication and to further understand its interaction with Vpr. The infectivity of our mutants suggests that, unlike p12, p6 is not important for early viral replication. Consistent with this, we observed that p6 is rapidly lost upon target cell entry in time-course immunoblotting experiments. By analysing Vpr incorporation in p6 mutant virions, we identified that the 15-FRFG-18 and 41-LXXLF-45 motifs previously identified as putative Vpr-binding sites are important for Vpr recruitment, but that the 34-ELY-36 motif also suggested to be a Vpr-binding site is dispensable. Additionally, disrupting Vpr oligomerization together with removing either binding motif in p6 reduced Vpr incorporation ∼25-50-fold more than inhibiting Vpr oligomerization alone and ∼10-25-fold more than deletion of each p6 motif alone, implying that multivalency/avidity is important for the interaction. Interestingly, using immunoblotting and immunofluorescence, we observed that most of Vpr is lost concomitantly with p6 during infection, but that a small fraction remains associated with the viral capsid for several hours. This has implications for the function of Vpr in early replication. Importance The p12 protein of MLV and the p6 protein of HIV-1 are both supplementary Gag cleavage products that carry proline-rich motifs which facilitate virus budding. Importantly, p12 has also been found to be essential for early viral replication events. However, whilst Vpr, the only accessory protein packaged into HIV-1 virions, is recruited via the p6 region of Gag, the function of both mature p6 and Vpr in early replication is unclear. Here, we have systematically mutated the p6 region of gag and have studied the effects on HIV infectivity and Vpr packaging. We have also investigated what happens to p6 and Vpr during early infection. We show that, unlike p12, mature p6 is not required for early replication and that most of the mature p6, and the Vpr that it recruits, are lost rapidly upon target cell entry. This has implications for the role of Vpr in target cells.

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