scholarly journals Membrane Interface-Interacting Sequences within the Ectodomain of the Human Immunodeficiency Virus Type 1 Envelope Glycoprotein: Putative Role during Viral Fusion

2000 ◽  
Vol 74 (17) ◽  
pp. 8038-8047 ◽  
Author(s):  
Tatiana Suárez ◽  
William R. Gallaher ◽  
Aitziber Agirre ◽  
Félix M. Goñi ◽  
José L. Nieva
Keyword(s):  
Human Immunodeficiency Virus ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fusion Peptide ◽  
Viral Fusion ◽  
Membrane Interface ◽  
Immunodeficiency Virus ◽  
Transmembrane Anchor

ABSTRACT We have identified a region within the ectodomain of the fusogenic human immunodeficiency virus type 1 (HIV-1) gp41, different from the fusion peptide, that interacts strongly with membranes. This conserved sequence, which immediately precedes the transmembrane anchor, is not highly hydrophobic according to the Kyte-Doolittle hydropathy prediction algorithm, yet it shows a high tendency to partition into the membrane interface, as revealed by the Wimley-White interfacial hydrophobicity scale. We have investigated here the membrane effects induced by NH2-DKWASLWNWFNITNWLWYIK-CONH2(HIVc), the membrane interface-partitioning region at the C terminus of the gp41 ectodomain, in comparison to those caused by NH2-AVGIGALFLGFLGAAGSTMGARS-CONH2(HIVn), the fusion peptide at the N terminus of the subunit. Both HIVc and HIVn were seen to induce membrane fusion and permeabilization, although lower doses of HIVc were required for comparable effects to be detected. Experiments in which equimolar mixtures of HIVc and HIVn were used indicated that both peptides may act in a cooperative way. Peptide-membrane and peptide-peptide interactions underlying those effects were further confirmed by analyzing the changes in fluorescence of peptide Trp residues. Replacement of the first three Trp residues by Ala, known to render a defective gp41 phenotype unable to mediate both cell-cell fusion and virus entry, also abrogated the HIVc ability to induce membrane fusion or form complexes with HIVn but not its ability to associate with vesicles. Hydropathy analysis indicated that the presence of two membrane-partitioning stretches separated by a collapsible intervening sequence is a common structural motif among other viral envelope proteins. Moreover, sequences with membrane surface-residing residues preceding the transmembrane anchor appeared to be a common feature in viral fusion proteins of several virus families. According to our experimental results, such a feature might be related to their fusogenic function.

scholarly journals Role of Cholesterol in Human Immunodeficiency Virus Type 1 Envelope Protein-Mediated Fusion with Host Cells

2002 ◽  
Vol 76 (22) ◽  
pp. 11584-11595 ◽  
Author(s):  
Mathias Viard ◽  
Isabella Parolini ◽  
Massimo Sargiacomo ◽  
Katia Fecchi ◽  
Carlo Ramoni ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Laser Scanning Microscopy ◽  
Host Cells ◽  
Cholesterol Depletion ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT In this study we examined the effects of target membrane cholesterol depletion and cytoskeletal changes on human immunodeficiency virus type 1 (HIV-1) Env-mediated membrane fusion by dye redistribution assays. We found that treatment of peripheral blood lymphocytes (PBL) with methyl-β-cyclodextrin (MβCD) or cytochalasin reduced their susceptibility to membrane fusion with cells expressing HIV-1 Env that utilize CXCR4 or CCR5. However, treatment of human osteosarcoma (HOS) cells expressing high levels of CD4 and coreceptors with these agents did not affect their susceptibility to HIV-1 Env-mediated membrane fusion. Removal of cholesterol inhibited stromal cell-derived factor-1α- and macrophage inflammatory protein 1β-induced chemotaxis of both PBL and HOS cells expressing CD4 and coreceptors. The fusion activity as well as the chemotactic activity of PBL was recovered by adding back cholesterol to these cells. Confocal laser scanning microscopy analysis indicated that treatment of lymphocytes with MβCD reduced the colocalization of CD4 or of CXCR4 with actin presumably in microvilli. These findings indicate that, although cholesterol is not required for HIV-1 Env-mediated membrane fusion per se, its depletion from cells with relatively low coreceptor densities reduces the capacity of HIV-1 Env to engage coreceptor clusters required to trigger fusion. Furthermore, our results suggest that coreceptor clustering may occur in microvilli that are supported by actin polymerization.

Membrane destabilization induced by the human immunodeficiency virus type-1 fusion peptide

1997 ◽  
Vol 4 (4-6) ◽  
pp. 365-369
Author(s):  
José L. Nieva ◽  
Félix M. Goñi ◽  
Arturo Muga ◽  
Shlomo Nir ◽  
Francisca Pereira
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fusion Peptide ◽  
Immunodeficiency Virus ◽  
Membrane Destabilization

scholarly journals Regulation of Human Immunodeficiency Virus Type 1 Env-Mediated Membrane Fusion by Viral Protease Activity

2004 ◽  
Vol 78 (2) ◽  
pp. 1026-1031 ◽  
Author(s):  
Tsutomu Murakami ◽  
Sherimay Ablan ◽  
Eric O. Freed ◽  
Yuetsu Tanaka
Keyword(s):  
Human Immunodeficiency Virus ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cytoplasmic Tail ◽  
Target Cells ◽  
Gag Protein ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT We and others have presented evidence for a direct interaction between the matrix (MA) domain of the human immunodeficiency virus type 1 (HIV-1) Gag protein and the cytoplasmic tail of the transmembrane envelope (Env) glycoprotein gp41. In addition, it has been postulated that the MA domain of Gag undergoes a conformational change following Gag processing, and the cytoplasmic tail of gp41 has been shown to modulate Env-mediated membrane fusion activity. Together, these results raise the possibility that the interaction between the gp41 cytoplasmic tail and MA is regulated by protease (PR)-mediated Gag processing, perhaps affecting Env function. To examine whether Gag processing affects Env-mediated fusion, we compared the ability of wild-type (WT) HIV-1 Env and a mutant lacking the gp41 cytoplasmic tail to induce fusion in the context of an active (PR+) or inactive (PR−) viral PR. We observed that PR− virions bearing WT Env displayed defects in cell-cell fusion. Impaired fusion did not appear to be due to differences in the levels of virion-associated Env, in CD4-dependent binding to target cells, or in the formation of the CD4-induced gp41 six-helix bundle. Interestingly, truncation of the gp41 cytoplasmic tail reversed the fusion defect. These results suggest that interactions between unprocessed Gag and the gp41 cytoplasmic tail suppress fusion.

scholarly journals Inhibitory Effects of Small-Molecule CCR5 Antagonists on Human Immunodeficiency Virus Type 1 Envelope-Mediated Membrane Fusion and Viral Replication

2001 ◽  
Vol 45 (12) ◽  
pp. 3538-3543 ◽  
Author(s):  
Katsunori Takashima ◽  
Hiroshi Miyake ◽  
Rika A. Furuta ◽  
Jun-Ichi Fujisawa ◽  
Yuji Iizawa ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Replication ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Small Molecule ◽  
Inhibitory Effects ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT We established a human immunodeficiency virus type 1 (HIV-1) envelope (Env)-mediated membrane fusion assay and examined the small-molecule CCR5 antagonist TAK-779 and its derivatives for their inhibitory effects on HIV-1 Env-mediated membrane fusion and viral replication. The membrane fusion assay is based on HIV-1 long terminal repeat-directed β-d-galactosidase reporter gene expression in CD4- and CCR5-expressed HeLa (MAGI-CCR5) cells after cocultivation with effector 293T cells expressing HIV-1 Env. Inhibition of HIV-1 replication was also determined in MAGI-CCR5 cells infected with the corresponding cell-free HIV-1. TAK-779 effectively suppressed R5 HIV-1 (strain JR-FL) Env-mediated membrane fusion as well as viral replication. Its 50% inhibitory concentrations (IC50s) for membrane fusion and viral replication were 0.87 ± 0.11 and 1.4 ± 0.1 nM, respectively. These values corresponded well to the IC50 for 125I-RANTES (regulated on activation, T cell expressed, and secreted) binding to CCR5 (1.4 nM). The inhibitory effects of 18 TAK-779 derivatives on membrane fusion differed from one compound to another. However, there was a close correlation among their inhibitory effects on membrane fusion, viral replication, and RANTES binding. The correlation coefficient between their IC50s for membrane fusion and viral replication was 0.881. Furthermore, since this assay depends on Env expressed in the effector cells, it is also applicable to the evaluation of CXCR4 antagonists. These results indicate that the HIV-1 Env-mediated membrane fusion assay is a useful tool for the evaluation of entry inhibitors.

Virus-cell membrane fusion does not predict efficient infection of alveolar macrophages by human immunodeficiency virus type 1 (HIV-1)

Virology ◽  
1992 ◽  
Vol 188 (2) ◽  
pp. 864-868 ◽  
Author(s):  
Mary Jane Potash ◽  
Michael Zeira ◽  
Zheng-Bo Huang ◽  
Tillman E. Pearce ◽  
Edward Eden ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Membrane ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Alveolar Macrophages ◽  
Immunodeficiency Virus ◽  
Hiv 1

scholarly journals Part of the C-terminal tail of the envelope gp41 transmembrane glycoprotein of human immunodeficiency virus type 1 is exposed on the surface of infected cells and is involved in virus-mediated cell fusion

2005 ◽  
Vol 86 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Linda Cheung ◽  
Lesley McLain ◽  
Mark J. Hollier ◽  
Steven A. Reading ◽  
Nigel J. Dimmock
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Matrix Protein ◽  
Viral Fusion ◽  
Transmembrane Glycoprotein ◽  
Immunodeficiency Virus ◽  
Hiv 1

The C-terminal tail of the gp41 transmembrane glycoprotein of the human immunodeficiency virus type 1 (HIV-1) virion is usually thought to be inside the virion, but it has been shown recently that part of the tail is exposed on the virion exterior. Here, using a panel of antibodies, it was demonstrated that the same part of the tail is exposed on the surface of HIV-1-infected C8166 lymphoblastoid cells and HeLa cells infected with a gp41-expressing vaccinia virus recombinant. Both types of infected cell failed to react with p17 matrix protein-specific IgGs until permeabilized with saponin, confirming the integrity of the plasma membrane. Cell-surface exposure of the gp41 tail was independently demonstrated by inhibition of HIV-1-mediated cell–cell fusion by one of the gp41 tail-specific antibodies. These data also implicate the exposed region of the gp41 C-terminal tail either directly or indirectly in the viral fusion process. Its surface exposure suggests that the gp41 C-terminal tail may be a candidate for immune intervention or chemotherapy of infection.

scholarly journals CCR5 and CXCR4 Usage by Non-Clade B Human Immunodeficiency Virus Type 1 Primary Isolates

2002 ◽  
Vol 76 (6) ◽  
pp. 3059-3064 ◽  
Author(s):  
Daniah A. D. Thompson ◽  
Emmanuel G. Cormier ◽  
Tatjana Dragic
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Fusion ◽  
Amino Terminal ◽  
Cxcr4 Usage ◽  
Clade B ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT CCR5 and CXCR4 usage has been studied extensively with a variety of clade B human immunodeficiency virus type 1 (HIV-1) isolates. The determinants of CCR5 coreceptor function are remarkably consistent, with a region critical for fusion and entry located in the CCR5 amino-terminal domain (Nt). In particular, negatively charged amino acids and sulfated tyrosines in the Nt are essential for gp120 binding to CCR5. The same types of residues are important for CXCR4-mediated viral fusion and entry, but they are dispersed throughout the extracellular domains of CXCR4, and their usage is isolate dependent. Here, we report on the determinants of CCR5 and CXCR4 coreceptor function for a panel of non-clade B isolates that are responsible for the majority of new HIV-1 infections worldwide. Consistent with clade B isolates, CXCR4 usage remains isolate dependent and is determined by the overall content of negatively charged and tyrosine residues. Residues in the Nt of CCR5 that are important for fusion and entry of clade B isolates are also important for the entry of all non-clade B HIV-1 isolates that we tested. Surprisingly, we found that in contrast to clade B isolates, a cluster of residues in the second extracellular loop of CCR5 significantly affects fusion and entry of all non-clade B isolates tested. This points to a different mechanism of CCR5 usage by these viruses and may have important implications for the development of HIV-1 inhibitors that target CCR5 coreceptor function.

scholarly journals Subdomain Folding and Biological Activity of the Core Structure from Human Immunodeficiency Virus Type 1 gp41: Implications for Viral Membrane Fusion

1999 ◽  
Vol 73 (5) ◽  
pp. 4433-4438 ◽  
Author(s):  
Min Lu ◽  
Hong Ji ◽  
Steven Shen
Keyword(s):  
Human Immunodeficiency Virus ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Covalent Attachment ◽  
Direct Role ◽  
The Core ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) consists of two subunits, gp120 and gp41. The extraviral portion (ectodomain) of gp41 contains an α-helical domain that likely represents the core of the fusion-active conformation of the molecule. Here we report the identification and characterization of a minimal, autonomous folding subdomain that retains key determinants in specifying the overall fold of the gp41 ectodomain core. This subdomain, designated N34(L6)C28, is formed by covalent attachment of peptides N-34 and C-28 by a short flexible linker in place of the normal disulfide-bonded loop sequence. N34(L6)C28 forms a highly thermostable, α-helical trimer. Point mutations within the envelope protein complex that abolish membrane fusion and HIV-1 infectivity also impede the formation of the N34(L6)C28 core. Moreover, N34(L6)C28 is capable of inhibiting HIV-1 envelope-mediated membrane fusion. Taken together, these results indicate that the N34(L6)C28 core plays a direct role in the membrane fusion step of HIV-1 infection and thus provides a molecular target for the development of antiviral pharmaceutical agents.

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