Roles played by acidic lipids in HIV-1 Gag membrane binding

Olety, Balaji; Ono, Akira

doi:10.1016/j.virusres.2014.06.015

Cited by 39 publications

(39 citation statements)

References 122 publications

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“…Indeed, due to its high affinity for the myristoylated Gag, PI(4,5)P 2 can outcompete RNA bound to the myristoylated GagMA domain (58,61,63,66). In contrast, results in Fig.…”

Section: Discussionmentioning

confidence: 87%

“…Interestingly, RNAs have been shown to decrease the affinity of MA for lipid membranes (61,62). Thus, RNAs and notably gRNA may act as negative regulators of nonspecific membrane binding, likely by reducing the electrostatic interactions of the HBR with acidic lipids and preventing myristate exposure (62,63). Phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P 2 ] and probably other phosphoinositides (64,65), which are essentially found on the cytoplasmic leaflet of the PM, can outcompete gRNA (61,66) and promote the anchoring of the myristoylated MA domain to the PM (62,67).…”

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confidence: 99%

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The HIV-1 Nucleocapsid Protein Recruits Negatively Charged Lipids To Ensure Its Optimal Binding to Lipid Membranes

Kempf

Postupalenko

Bora

et al. 2015

J Virol

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The HIV-1 Gag polyprotein precursor composed of the matrix (MA), capsid (CA), nucleocapsid (NC), and p6 domains orchestrates virus assembly via interactions between MA and the cell plasma membrane (PM) on one hand and NC and the genomic RNA on the other hand. As the Gag precursor can adopt a bent conformation, a potential interaction of the NC domain with the PM cannot be excluded during Gag assembly at the PM. To investigate the possible interaction of NC with lipid membranes in the absence of any interference from the other domains of Gag, we quantitatively characterized by fluorescence spectroscopy the binding of the mature NC protein to large unilamellar vesicles (LUVs) used as membrane models. We found that NC, either in its free form or bound to an oligonucleotide, was binding with high affinity (ϳ10 7 M ؊1 ) to negatively charged LUVs. The number of NC binding sites, but not the binding constant, was observed to decrease with the percentage of negatively charged lipids in the LUV composition, suggesting that NC and NC/oligonucleotide complexes were able to recruit negatively charged lipids to ensure optimal binding. However, in contrast to MA, NC did not exhibit a preference for phosphatidylinositol-(4,5)-bisphosphate. These results lead us to propose a modified Gag assembly model where the NC domain contributes to the initial binding of the bent form of Gag to the PM. IMPORTANCEThe NC protein is a highly conserved nucleic acid binding protein that plays numerous key roles in HIV-1 replication. While accumulating evidence shows that NC either as a mature protein or as a domain of the Gag precursor also interacts with host proteins, only a few data are available on the possible interaction of NC with lipid membranes. Interestingly, during HIV-1 assembly, the Gag precursor is thought to adopt a bent conformation where the NC domain may interact with the plasma membrane. In this context, we quantitatively characterized the binding of NC, as a free protein or as a complex with nucleic acids, to lipid membranes and showed that the latter constitute a binding platform for NC. Taken together, our data suggest that the NC domain may play a role in the initial binding events of Gag to the plasma membrane during HIV-1 assembly.T he nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) is a small basic nucleic acid binding protein with two strictly conserved CCHC motifs that strongly bind zinc (1). Mature NC results from the protease-mediated cleavage of the Gag polyprotein precursor and plays key roles in HIV-1 replication (2-5). During the early steps, NC acts as a cofactor of the reverse transcriptase (RT), to promote the initiation of reverse transcription (6-8), as well as the two obligatory strand transfers (9, 10). Moreover, NC also reduces RT pauses at the initiation step (11-13), increases the overall RT processivity (14, 15), promotes synthesis through pause sites (16-19), helps to remove the RNA fragments resulting from the RT RNase H activity (20), and may contribute to the pro...

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“…Indeed, due to its high affinity for the myristoylated Gag, PI(4,5)P 2 can outcompete RNA bound to the myristoylated GagMA domain (58,61,63,66). In contrast, results in Fig.…”

Section: Discussionmentioning

confidence: 87%

mentioning

confidence: 99%

The HIV-1 Nucleocapsid Protein Recruits Negatively Charged Lipids To Ensure Its Optimal Binding to Lipid Membranes

Kempf

Postupalenko

Bora

et al. 2015

J Virol

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“…In the absence of nucleic acid, a similar conformation of Gag was observed by neutron reflectivity on negatively charged membranes, but upon increasing nucleic acid concentration, the Gag protein assumed the elongated shape that persists in the immature virus [6]. Whereas it is established that the nucleocapsid (NC) domain of Gag specifically recognizes motifs in the viral RNA genome for packaging [7, 8], there is compelling evidence that the matrix (MA) domain also binds to cellular RNA [9-11]. …”

Section: Introductionmentioning

confidence: 90%

HIV-1 matrix-31 membrane binding peptide interacts differently with membranes containing PS vs. PI(4,5)P2

O'neil

Andenoro

Pagano

et al. 2016

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Efficient assembly of HIV-1 at the plasma membrane (PM) of the T-cell specifically requires PI(4,5)P2. It was previously shown that a highly basic region (HBR) of the matrix protein (MA) on the Gag precursor polyprotein Pr55Gag is required for membrane association. MA is N-terminally myristoylated, which enhances its affinity to membranes. In this work we used X-ray scattering and neutron reflectivity to determine how the physical properties and structure of lipid bilayers respond to the addition of binding domain peptides, either in the myristoylated form (MA31myr) or without the myristoyl group (MA31). Neutron reflectivity measurements showed the peptides predominantly located in the hydrocarbon interior. Diffuse X-ray scattering showed differences in membrane properties upon addition of peptides and the direction of the changes depended on lipid composition. The PI(4,5)P2-containing bilayers softened, thinned and became less ordered as peptide concentration increased. In contrast, POPS-containing bilayers with equivalent net charge first stiffened, thickened and became more ordered with increasing peptide concentration. As softening the host cell’s PM upon contact with the protein lowers the free energy for membrane restructuring, thereby potentially facilitating budding of viral particles, our results suggest that the role of PI(4,5)P2 in viral assembly goes beyond specific stereochemical membrane binding. These studies reinforce the importance of lipids in virology.

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“…To date, many lipidbinding proteins identified have recognized two specific lipids or a specific lipid and membrane physical property such as curvature (58). For instance, the HIV-1 matrix domain has recently been shown to have additional binding sites for plasma membrane lipids (53,59) in addition to consensus PI(4,5)P 2 binding (60). The HIV-1 matrix domain is also sensitive to the acyl chain composition and cholesterol content of membranes (52).…”

mentioning

confidence: 99%

Host Cell Plasma Membrane Phosphatidylserine Regulates the Assembly and Budding of Ebola Virus

Adu-Gyamfi

Johnson

Fraser

et al. 2015

J Virol

199

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Lipid-enveloped viruses replicate and bud from the host cell where they acquire their lipid coat. Ebola virus, which buds from the plasma membrane of the host cell, causes viral hemorrhagic fever and has a high fatality rate. To date, little has been known about how budding and egress of Ebola virus are mediated at the plasma membrane. We have found that the lipid phosphatidylserine (PS) regulates the assembly of Ebola virus matrix protein VP40. VP40 binds PS-containing membranes with nanomolar affinity, and binding of PS regulates VP40 localization and oligomerization on the plasma membrane inner leaflet. Further, alteration of PS levels in mammalian cells inhibits assembly and egress of VP40. Notably, interactions of VP40 with the plasma membrane induced exposure of PS on the outer leaflet of the plasma membrane at sites of egress, whereas PS is typically found only on the inner leaflet. Taking the data together, we present a model accounting for the role of plasma membrane PS in assembly of Ebola virus-like particles. IMPORTANCEThe lipid-enveloped Ebola virus causes severe infection with a high mortality rate and currently lacks FDA-approved therapeutics or vaccines. Ebola virus harbors just seven genes in its genome, and there is a critical requirement for acquisition of its lipid envelope from the plasma membrane of the human cell that it infects during the replication process. There is, however, a dearth of information available on the required contents of this envelope for egress and subsequent attachment and entry. Here we demonstrate that plasma membrane phosphatidylserine is critical for Ebola virus budding from the host cell plasma membrane. This report, to our knowledge, is the first to highlight the role of lipids in human cell membranes in the Ebola virus replication cycle and draws a clear link between selective binding and transport of a lipid across the membrane of the human cell and use of that lipid for subsequent viral entry. Lipid-enveloped viruses harbor a lipid membrane bilayer derived from their host cell during the budding process. This envelope provides the virus stability, protection of its genetic contents, and a reservoir for its transmembrane glycoprotein, which mediates entry into cells (1, 2). The viral lipid envelope may be a viable target for drug development, as particular alterations in the lipid coat or receptor-lipid interaction can inhibit viral entry (3-6). The lipid-dependent budding and egress of some lipid-enveloped viruses have been investigated. For example, it is well established that HIV-1 binds and utilizes 1,2-dioleoyl-sn-glycero-3-phospho-(1=-myo-inositol-4=,5=-bisphosphate) [PI(4,5)P 2 ] enriched in the plasma membrane (PM) inner leaflet for assembly and egress from the cell (7,8). Enteroviruses and flaviviruses use a phosphatidylinositol-4-phosphate [PI(4)P]-enriched organelle to replicate (9), and enteroviruses are packaged into phosphatidylserine (PS)-enriched vesicles, thereby enhancing the efficiency of viral transmission (10). The budding and egres...

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Roles played by acidic lipids in HIV-1 Gag membrane binding

Cited by 39 publications

References 122 publications

The HIV-1 Nucleocapsid Protein Recruits Negatively Charged Lipids To Ensure Its Optimal Binding to Lipid Membranes

The HIV-1 Nucleocapsid Protein Recruits Negatively Charged Lipids To Ensure Its Optimal Binding to Lipid Membranes

HIV-1 matrix-31 membrane binding peptide interacts differently with membranes containing PS vs. PI(4,5)P2

Host Cell Plasma Membrane Phosphatidylserine Regulates the Assembly and Budding of Ebola Virus

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