scholarly journals Self assembly of HIV-1 Gag protein on lipid membranes generates PI(4,5)P2/Cholesterol nanoclusters

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Naresh Yandrapalli ◽  
Quentin Lubart ◽  
Hanumant S. Tanwar ◽  
Catherine Picart ◽  
Johnson Mak ◽  
...  
Keyword(s):  
Self Assembly ◽  
Lipid Membranes ◽  
Gag Protein ◽  
Hiv 1

scholarly journals Self assembly of HIV-1 Gag protein on lipid membranes generates PI(4,5)P2/Cholesterol nanoclusters

2016 ◽  
Author(s):  
Naresh Yandrapalli ◽  
Quentin Lubart ◽  
Hanumant S. Tanwar ◽  
Catherine Picart ◽  
Johnson Mak ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Membrane Lipids ◽  
Virus Assembly ◽  
Specific Interaction ◽  
Membrane Lipid ◽  
Gag Protein ◽  
Gag Polyprotein ◽  
Hiv 1

AbstractThe self-assembly of HIV-1 Gag polyprotein at the inner leaflet of the cell host plasma membrane is the key orchestrator of virus assembly. The binding between Gag and the plasma membrane is mediated by specific interaction of the Gag matrix domain and the PI(4,5)P2 lipid (PIP2). It is unknown whether this interaction could lead to local reorganization of the plasma membrane lipids. In this study, using model membranes, we examined the ability of Gag to segregate specific lipids upon self-assembly. We show for the first time that Gag self-assembly is responsible for the formation of PIP2 lipid nanoclusters, enriched in cholesterol but not in sphingomyelin. We also show that Gag mainly partition into liquid-disordered domains of these lipid membranes. Our work strongly suggests that, instead of targeting pre-existing plasma membrane lipid domains, Gag is more prone to generate PIP2/Cholesterol lipid nanodomains at the inner leaflet of the plasma membrane during early events of virus assembly.

scholarly journals Binding Mechanism of the Matrix Domain of HIV-1 Gag on Lipid Membranes

2020 ◽  
Author(s):  
V. Monje-Galvan ◽  
Gregory A. Voth
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Electrostatic Interactions ◽  
Membrane Dynamics ◽  
Collective Effects ◽  
Gag Protein ◽  
Matrix Domain ◽  
Viral Budding ◽  
The Matrix ◽  
Hiv 1

AbstractAggregation of the HIV-1 Gag protein onto the plasma membrane (PM) enables viral budding and infection propagation. Gag assembly at the membrane interface is mediated by its matrix domain (MA), the Myristoylated (Myr) N-terminus. MA targets the PM through electrostatic interactions, mainly at its highly-basic-region (HBR). The mechanism of Myr insertion and its role in protein-membrane dynamics remains unclear. Using all-atom molecular dynamics, we examined an MA unit in the vicinity of lipid bilayers that model different characteristics of the PM. Interaction with PIP2 and PS lipids is highly favored around the HBR, and is enough to keep the protein bound. Additionally, we simulated three MA units near our bilayers and quantified the collective effects of free monomers vs. formed trimers on Myr insertion events. Micro-second-long trajectories allowed us to observe Myr insertion, propose a mechanism, quantify specific interactions with lipids, and examine the response of the local membrane environment.

scholarly journals Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 11
Author(s):  
Damian Dziubak ◽  
Kamil Strzelak ◽  
Slawomir Sek
Keyword(s):  
Electrochemical Properties ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Membrane Resistance ◽  
Electrochemical Characteristics ◽  
Freeze Thaw ◽  
Lipid Films ◽  
Supported Lipid Membranes

Supported lipid membranes are widely used platforms which serve as simplified models of cell membranes. Among numerous methods used for preparation of planar lipid films, self-assembly of bicelles appears to be promising strategy. Therefore, in this paper we have examined the mechanism of formation and the electrochemical properties of lipid films deposited onto thioglucose-modified gold electrodes from bicellar mixtures. It was found that adsorption of the bicelles occurs by replacement of interfacial water and it leads to formation of a double bilayer structure on the electrode surface. The resulting lipid assembly contains numerous defects and pinholes which affect the permeability of the membrane for ions and water. Significant improvement in morphology and electrochemical characteristics is achieved upon freeze–thaw treatment of the deposited membrane. The lipid assembly is rearranged to single bilayer configuration with locally occurring patches of the second bilayer, and the number of pinholes is substantially decreased. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced, which was manifested by the relatively high value of the membrane resistance.

scholarly journals Functional Replacement and Positional Dependence of Homologous and Heterologous L Domains in Equine Infectious Anemia Virus Replication

2002 ◽  
Vol 76 (4) ◽  
pp. 1569-1577 ◽  
Author(s):  
Feng Li ◽  
Chaoping Chen ◽  
Bridget A. Puffer ◽  
Ronald C. Montelaro
Keyword(s):  
Life Cycle ◽  
Virus Particle ◽  
Matrix Protein ◽  
Particle Production ◽  
Equine Infectious Anemia Virus ◽  
Virus Infectivity ◽  
Gag Protein ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
Hiv 1

ABSTRACT We have previously demonstrated by Gag polyprotein budding assays that the Gag p9 protein of equine infectious anemia virus (EIAV) utilizes a unique YPDL motif as a late assembly domain (L domain) to facilitate release of the budding virus particle from the host cell plasma membrane (B. A. Puffer, L. J. Parent, J. W. Wills, and R. C. Montelaro, J. Virol. 71:6541-6546, 1997). To characterize in more detail the role of the YPDL L domain in the EIAV life cycle, we have examined the replication properties of a series of EIAV proviral mutants in which the parental YPDL L domain was replaced by a human immunodeficiency virus type 1 (HIV-1) PTAP or Rous sarcoma virus (RSV) PPPY L domain in the p9 protein or by proviruses in which the parental YPDL or HIV-1 PTAP L domain was inserted in the viral matrix protein. The replication properties of these L-domain variants were examined with respect to Gag protein expression and processing, virus particle production, and virus infectivity. The data from these experiments indicate that (i) the YPDL L domain of p9 is required for replication competence (assembly and infectivity) in equine cell cultures, including the natural target equine macrophages; (ii) all of the functions of the YPDL L domain in the EIAV life cycle can be replaced by replacement of the parental YPDL sequence in p9 with the PTAP L-domain segment of HIV-1 p6 or the PPPY L domain of RSV p2b; and (iii) the assembly, but not infectivity, functions of the EIAV proviral YPDL substitution mutants can be partially rescued by inclusions of YPDL and PTAP L-domain sequences in the C-terminal region of the EIAV MA protein. Taken together, these data demonstrate that the EIAV YPDL L domain mediates distinct functions in viral budding and infectivity and that the HIV-1 PTAP and RSV PPPY L domains can effectively facilitate these dual replication functions in the context of the p9 protein. In light of the fact that YPDL, PTAP, and PPPY domains evidently have distinct characteristic binding specificities, these observations may indicate different portals into common cellular processes that mediate EIAV budding and infectivity, respectively.

scholarly journals Analysis of Human Immunodeficiency Virus Type 1 Gag Dimerization-Induced Assembly

2005 ◽  
Vol 79 (23) ◽  
pp. 14498-14506 ◽  
Author(s):  
Ayna Alfadhli ◽  
Tenzin Choesang Dhenub ◽  
Amelia Still ◽  
Eric Barklis
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Protein Assembly ◽  
Particle Assembly ◽  
Gag Protein ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Terminal Domains

ABSTRACT The nucleocapsid (NC) domains of retrovirus precursor Gag (PrGag) proteins play an essential role in virus assembly. Evidence suggests that NC binding to viral RNA promotes dimerization of PrGag capsid (CA) domains, which triggers assembly of CA N-terminal domains (NTDs) into hexamer rings that are interconnected by CA C-terminal domains. To examine the influence of dimerization on human immunodeficiency virus type 1 (HIV-1) Gag protein assembly in vitro, we analyzed the assembly properties of Gag proteins in which NC domains were replaced with cysteine residues that could be linked via chemical treatment. In accordance with the model that Gag protein pairing triggers assembly, we found that cysteine cross-linking or oxidation reagents induced the assembly of virus-like particles. However, efficient assembly also was observed to be temperature dependent or required the tethering of NTDs. Our results suggest a multistep pathway for HIV-1 Gag protein assembly. In the first step, Gag protein pairing through NC-RNA interactions or C-terminal cysteine linkage fosters dimerization. Next, a conformational change converts assembly-restricted dimers or small oligomers into assembly-competent ones. At the final stage, final particle assembly occurs, possibly through a set of larger intermediates.

scholarly journals The effect of polyethylene glycol-modified lipids on the interaction of HIV-1 derived peptide–dendrimer complexes with lipid membranes

2016 ◽  
Vol 1858 (12) ◽  
pp. 3005-3016 ◽  
Author(s):  
Sophie Melikishvili ◽  
Alexandra Poturnayova ◽  
Maksim Ionov ◽  
Maria Bryszewska ◽  
Tomáš Vary ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Lipid Membranes ◽  
Peptide Dendrimer ◽  
Hiv 1

scholarly journals The HIV-1 Nucleocapsid Regulates Its Own Condensation by Phase-Separated Activity-Enhancing Sequestration of the Viral Protease during Maturation

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2312
Author(s):  
Sébastien Lyonnais ◽  
S. Kashif Sadiq ◽  
Cristina Lorca-Oró ◽  
Laure Dufau ◽  
Sara Nieto-Marquez ◽  
...  
Keyword(s):  
Self Assembly ◽  
Rna Binding ◽  
Weak Interactions ◽  
Biological Functions ◽  
Viral Protease ◽  
Virus Maturation ◽  
Sequential Processing ◽  
Rnp Granules ◽  
Crowded Environments ◽  
Hiv 1

A growing number of studies indicate that mRNAs and long ncRNAs can affect protein populations by assembling dynamic ribonucleoprotein (RNP) granules. These phase-separated molecular ‘sponges’, stabilized by quinary (transient and weak) interactions, control proteins involved in numerous biological functions. Retroviruses such as HIV-1 form by self-assembly when their genomic RNA (gRNA) traps Gag and GagPol polyprotein precursors. Infectivity requires extracellular budding of the particle followed by maturation, an ordered processing of ∼2400 Gag and ∼120 GagPol by the viral protease (PR). This leads to a condensed gRNA-NCp7 nucleocapsid and a CAp24-self-assembled capsid surrounding the RNP. The choreography by which all of these components dynamically interact during virus maturation is one of the missing milestones to fully depict the HIV life cycle. Here, we describe how HIV-1 has evolved a dynamic RNP granule with successive weak–strong–moderate quinary NC-gRNA networks during the sequential processing of the GagNC domain. We also reveal two palindromic RNA-binding triads on NC, KxxFxxQ and QxxFxxK, that provide quinary NC-gRNA interactions. Consequently, the nucleocapsid complex appears properly aggregated for capsid reassembly and reverse transcription, mandatory processes for viral infectivity. We show that PR is sequestered within this RNP and drives its maturation/condensation within minutes, this process being most effective at the end of budding. We anticipate such findings will stimulate further investigations of quinary interactions and emergent mechanisms in crowded environments throughout the wide and growing array of RNP granules.

Self-Healing Bilayer Lipid Membranes Formed Over Synthetic Substrates

2008 ◽  
Author(s):  
M. Austin Creasy ◽  
Donald J. Leo
Keyword(s):  
Self Assembly ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Bilayer Lipid Membrane ◽  
Unique Property ◽  
Bilayer Lipid Membranes ◽  
Self Healing ◽  
Electrical Field ◽  
Bilayer Lipid ◽  
Recent Experimental Study

Biological systems demonstrate autonomous healing of damage and are an inspiration for developing self-healing materials. Our recent experimental study has demonstrated that a bilayer lipid membrane (BLM), also called a black lipid membrane, has the ability to self-heal after mechanical failure. These molecules have a unique property that they spontaneously self assembly into organized structures in an aqueous medium. The BLM forms an impervious barrier to ions and fluid between two volumes and strength of the barrier is dependent on the pressure and electrical field applied to the membrane. A BLM formed over an aperture on a silicon substrate is shown to self-heal for 5 pressurization failure cycles.

scholarly journals Selective and Nonselective Packaging of Cellular RNAs in Retrovirus Particles

2007 ◽  
Vol 81 (12) ◽  
pp. 6623-6631 ◽  
Author(s):  
Samuel J. Rulli ◽  
Catherine S. Hibbert ◽  
Jane Mirro ◽  
Thoru Pederson ◽  
Shyam Biswal ◽  
...  
Keyword(s):  
Leukemia Virus ◽  
Signal Recognition Particle ◽  
Viral Rna ◽  
Genomic Rna ◽  
Gag Protein ◽  
Mrna Species ◽  
Reverse Transcription Pcr ◽  
Cellular Mrnas ◽  
A Minor ◽  
Hiv 1

ABSTRACT Assembly of retrovirus particles normally entails the selective encapsidation of viral genomic RNA. However, in the absence of packageable viral RNA, assembly is still efficient, and the released virus-like particles (termed “Ψ−” particles) still contain roughly normal amounts of RNA. We have proposed that cellular mRNAs replace the genome in Ψ− particles. We have now analyzed the mRNA content of Ψ− and Ψ+ murine leukemia virus (MLV) particles using both microarray analysis and real-time reverse transcription-PCR. The majority of mRNA species present in the virus-producing cells were also detected in Ψ− particles. Remarkably, nearly all of them were packaged nonselectively; that is, their representation in the particles was simply proportional to their representation in the cells. However, a small number of low-abundance mRNAs were greatly enriched in the particles. In fact, one mRNA species was enriched to the same degree as Ψ+ genomic RNA. Similar results were obtained with particles formed from the human immunodeficiency virus type 1 (HIV-1) Gag protein, and the same mRNAs were enriched in MLV and HIV-1 particles. The levels of individual cellular mRNAs were ∼5- to 10-fold higher in Ψ− than in Ψ+ MLV particles, in agreement with the idea that they are replacing viral RNA in the former. In contrast, signal recognition particle RNA was present at the same level in Ψ− and Ψ+ particles; a minor fraction of this RNA was weakly associated with genomic RNA in Ψ+ MLV particles.

scholarly journals Sequence Determinants in Gammaretroviral Env Cytoplasmic Tails Dictate Virus-Specific Pseudotyping Compatibility

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Yul Eum Song ◽  
Grace Y. Olinger ◽  
Sanath Kumar Janaka ◽  
Marc C. Johnson
Keyword(s):  
Viral Vectors ◽  
Leukemia Virus ◽  
Target Cells ◽  
Gag Protein ◽  
Factors Affecting ◽  
Gene Therapies ◽  
Viral Glycoproteins ◽  
Cytoplasmic Tails ◽  
Specific Manner ◽  
Hiv 1

ABSTRACTViruses can incorporate foreign glycoproteins to form infectious particles through a process known as pseudotyping. However, not all glycoproteins are compatible with all viruses. Despite the fact that viral pseudotyping is widely used, what makes a virus/glycoprotein pair compatible is poorly understood. To study this, we chose to analyze a gammaretroviral glycoprotein (Env) whose compatibility with different viruses could be modulated through small changes in its cytoplasmic tail (CT). One form of this glycoprotein is compatible with murine leukemia virus (MLV) particles but incompatible with human immunodeficiency virus type 1 (HIV-1) particles, while the second is compatible with HIV-1 particles but not with MLV particles. To decipher the factors affecting virus-specific Env incompatibility, we characterized Env incorporation, maturation, cell-to-cell fusogenicity, and virus-to-cell fusogenicity of each Env. The HIV-1 particle incompatibility correlated with less efficient cleavage of the R peptide by HIV-1 protease. However, the MLV particle incompatibility was more nuanced. MLV incompatibility appeared to be caused by lack of incorporation into particles, yet incorporation could be restored by further truncating the CT or by using a chimeric MLV Gag protein containing the HIV-1 MA without fully restoring infectivity. The MLV particle incompatibility appeared to be caused in part by fusogenic repression in MLV particles through an unknown mechanism. This study demonstrates that the Env CT can dictate functionality of Env within particles in a virus-specific manner.IMPORTANCEViruses utilize viral glycoproteins to efficiently enter target cells during infection. How viruses acquire viral glycoproteins has been studied to understand the pathogenesis of viruses and develop safer and more efficient viral vectors for gene therapies. The CTs of viral glycoproteins have been shown to regulate various stages of glycoprotein biogenesis, but a gap still remains in understanding the molecular mechanism of glycoprotein acquisition and functionality regarding the CT. Here, we studied the mechanism of how specific mutations in the CT of a gammaretroviral envelope glycoprotein distinctly affect infectivity of two different viruses. Different mutations caused failure of glycoproteins to function in a virus-specific manner due to distinct fusion defects, suggesting that there are virus-specific characteristics affecting glycoprotein functionality.

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