scholarly journals Binding of the C-terminal domain of the HIV-1 capsid protein to lipid membranes: a biophysical characterization

2006 ◽  
Vol 394 (1) ◽  
pp. 345-353 ◽  
Author(s):  
Francisco N. Barrera ◽  
Estefanía Hurtado-Gómez ◽  
María C. Lidón-Moya ◽  
José L. Neira
Keyword(s):  
Capsid Protein ◽  
Lipid Membranes ◽  
Three Dimensional ◽  
Lipid Vesicles ◽  
Lipid Binding ◽  
Scanning Calorimetry ◽  
Form Part ◽  
Virion Envelope ◽  
Hiv 1

The capsid protein, CA, of HIV-1 forms a capsid that surrounds the viral genome. However, recent studies have shown that an important proportion of the CA molecule does not form part of this capsid, and its location and function are still unknown. In the present work we show, by using fluorescence, differential scanning calorimetry and Fourier-transform infrared spectroscopy, that the C-terminal region of CA, CA-C, is able to bind lipid vesicles in vitro in a peripheral fashion. CA-C had a greater affinity for negatively charged lipids (phosphatidic acid and phosphatidylserine) than for zwitterionic lipids [PC/Cho/SM (equimolar mixture of phosphatidylcholine, cholesterol and sphingomyelin) and phosphatidylcholine]. The interaction of CA-C with lipid membranes was supported by theoretical studies, which predicted that different regions, occurring close in the three-dimensional CA-C structure, were responsible for the binding. These results show the flexibility of CA-C to undergo conformational rearrangements in the presence of different binding partners. We hypothesize that the CA molecules that do not form part of the mature capsid might be involved in lipid-binding interactions in the inner leaflet of the virion envelope.

Synthesis and in vitro Antiviral Properties of Amphiphilic Dinucleoside Phosphate Derivatives of 2′,3-dideoxycytidine (ddC)

1995 ◽  
Vol 6 (5) ◽  
pp. 320-326 ◽  
Author(s):  
H. Schott ◽  
M. P. Häussler ◽  
P. Gowland ◽  
A. Bender ◽  
H. von Briesen ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Micelle Formation ◽  
Human Monocytes ◽  
New Class ◽  
Antiviral Activities ◽  
Derivatives Of ◽  
Hiv 1

N4-hexadecyl-5′-0-(4-monomethoxytrityl)-2′-deoxycytidine-3′-hydrogenphosphonate and 5′-0-(4-monomethoxytrityl)-2′-deoxythymidine-3′-0-hydrogenphosphonate were condensed with 2′,3′-dideoxycytidine (ddC) according to the hydrogenphosphonate method to yield N4-hexadecyl-2′-deoxycytidylyl-(3′-5′)-2′,3′-dideoxycytidine (N4-hexadecyldC-ddC) and 2′-deoxythymidylyl-(3′-5′)-N4-palmitoyl-2′,3′-dideoxycytidine (dT-N4-palmddC). N4-palmitoyl-2′,3′-dideoxycytidine (N4-palmddC) was synthesized by reacting palmitic anhydride with ddC. Both dinucleoside phosphates have amphiphilic properties and represent a new class of ddC derivatives in which in the case of the dinucleosides, the ddC-5′-monophosphate is masked with lipophilic residues of variable stability. The ddC derivatives can be solubilized in water by micelle formation and, because they have lipophilic residues, they can be incorporated into the lipid membranes of liposomes. The ddC derivatives were shown to have antiviral activities comparable to those of AZT and ddC when tested in vitro against HIV-1-infected HeLa and H9 cells as well as infected human monocytes/macrophages.

scholarly journals A natural product inhibits the initiation of α-synuclein aggregation and suppresses its toxicity

2017 ◽  
Vol 114 (6) ◽  
pp. E1009-E1017 ◽  
Author(s):  
Michele Perni ◽  
Céline Galvagnion ◽  
Alexander Maltsev ◽  
Georg Meisl ◽  
Martin B. D. Müller ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Natural Product ◽  
Self Assembly ◽  
Lipid Membranes ◽  
Neuroblastoma Cells ◽  
Lipid Vesicles ◽  
Human Neuroblastoma

The self-assembly of α-synuclein is closely associated with Parkinson’s disease and related syndromes. We show that squalamine, a natural product with known anticancer and antiviral activity, dramatically affects α-synuclein aggregation in vitro and in vivo. We elucidate the mechanism of action of squalamine by investigating its interaction with lipid vesicles, which are known to stimulate nucleation, and find that this compound displaces α-synuclein from the surfaces of such vesicles, thereby blocking the first steps in its aggregation process. We also show that squalamine almost completely suppresses the toxicity of α-synuclein oligomers in human neuroblastoma cells by inhibiting their interactions with lipid membranes. We further examine the effects of squalamine in a Caenorhabditis elegans strain overexpressing α-synuclein, observing a dramatic reduction of α-synuclein aggregation and an almost complete elimination of muscle paralysis. These findings suggest that squalamine could be a means of therapeutic intervention in Parkinson’s disease and related conditions.

scholarly journals HIV-1 Capsid Protein Forms Spherical (Immature-Like) and Tubular (Mature-Like) Particles in Vitro: Structure Switching by pH-induced Conformational Changes

2001 ◽  
Vol 81 (1) ◽  
pp. 586-594 ◽  
Author(s):  
Lorna S. Ehrlich ◽  
Tianbo Liu ◽  
Suzanne Scarlata ◽  
Benjamin Chu ◽  
Carol A. Carter
Keyword(s):  
Capsid Protein ◽  
Conformational Changes ◽  
Structure Switching ◽  
Hiv 1

scholarly journals Structural basis for interorganelle phospholipid transport mediated by VAT-1

2020 ◽  
Vol 295 (10) ◽  
pp. 3257-3268 ◽  
Author(s):  
Yasunori Watanabe ◽  
Yasushi Tamura ◽  
Chika Kakuta ◽  
Seiya Watanabe ◽  
Toshiya Endo
Keyword(s):  
Lipid Membranes ◽  
Protein Transport ◽  
Lipid Binding ◽  
Structural Basis ◽  
Tryptophan Residues ◽  
Phospholipid Transfer ◽  
Binding Cavity ◽  
Acidic Phospholipids ◽  
Phospholipid Transport

Eukaryotic cells are compartmentalized to form organelles, whose functions rely on proper phospholipid and protein transport. Here we determined the crystal structure of human VAT-1, a cytosolic soluble protein that was suggested to transfer phosphatidylserine, at 2.2 Å resolution. We found that VAT-1 transferred not only phosphatidylserine but also other acidic phospholipids between membranes in vitro. Structure-based mutational analyses showed the presence of a possible lipid-binding cavity at the interface between the two subdomains, and two tyrosine residues in the flexible loops facilitated phospholipid transfer, likely by functioning as a gate to this lipid-binding cavity. We also found that a basic and hydrophobic loop with two tryptophan residues protruded from the molecule and facilitated binding to the acidic-lipid membranes, thereby achieving efficient phospholipid transfer.

Structural determinants of virion assembly and release in the C-terminus of the M-PMV capsid protein

2021 ◽  
Author(s):  
Marlene V. Buckmaster ◽  
Kaneil K. Zadrozny ◽  
Barbie K. Ganser-Pornillos ◽  
Owen Pornillos ◽  
Stephen P. Goff
Keyword(s):  
Capsid Protein ◽  
Conformational Changes ◽  
Structural Determinants ◽  
Particle Assembly ◽  
Gag Protein ◽  
Virion Assembly ◽  
C Terminus ◽  
Hiv 1

The transition from an immature to a fully infectious mature retrovirus particle is associated with molecular switches that trigger dramatic conformational changes in the structure of the Gag proteins. A dominant maturation switch that stabilizes the immature capsid lattice is located downstream of the capsid (CA) protein in many retroviral Gags. The HIV-1 Gag contains a stretch of five amino acid residues termed the ‘clasp motif’, important for the organization of the hexameric subunits that provide stability to the overall immature HIV-1 shell. Sequence alignment of the CA C-terminal domains (CTDs) of the HIV-1 and Mason-Pfizer Monkey Virus (M-PMV) highlighted a spacer-like domain in M-PMV that may provide comparable function. The importance of the sequences spanning the CA-NC cleavage has been demonstrated by mutagenesis, but the specific requirements for the clasp motif in several steps of M-PMV particle assembly and maturation have not been determined in detail. In the present study we report an examination of the role of the clasp motif in the M-PMV life cycle. We generated a series of M-PMV Gag mutants and assayed for assembly of the recombinant protein in vitro , and for the assembly, maturation, release, genomic RNA packaging, and infectivity of the mutant virus in vivo . The mutants revealed major defects in virion assembly and release in 293T and HeLa cells, and even larger defects in infectivity. Our data identifies the clasp motif as a fundamental contributor to CA-CTD interactions necessary for efficient viral infection. Importance The C-terminal domain of the capsid protein of many retroviruses has been shown to be critical for virion assembly and maturation, but the functions of this region of M-PMV are uncertain. We show that a short ‘clasp’ motif in the capsid domain of the M-PMV Gag protein plays a key role in M-PMV virion assembly, genome packaging, and infectivity.

scholarly journals Peptides Derived from the Reverse Transcriptase of Human Immunodeficiency Virus Type 1 as Novel Inhibitors of the Viral Integrase

2005 ◽  
Vol 280 (23) ◽  
pp. 21987-21996 ◽  
Author(s):  
Iris Oz Gleenberg ◽  
Orna Avidan ◽  
Yehuda Goldgur ◽  
Alon Herschhorn ◽  
Amnon Hizi
Keyword(s):  
Reverse Transcriptase ◽  
Catalytic Domain ◽  
Three Dimensional ◽  
Specific Protein ◽  
Strand Transfer ◽  
Catalytic Core ◽  
Core Domain ◽  
Inhibitory Peptides ◽  
Hiv 1

Recent studies have shown that the integrase (IN) of HIV-1 is inhibited in vitro by HIV-1 reverse transcriptase (RT). We further investigated the specific protein sequences of RT that were involved in this inhibition by screening a complete library of RT-derived peptides for their inhibition of IN activities. Two 20-residue peptides, peptide 4286, derived from the RT DNA polymerase domain, and the one designated 4321, from the RT ribonuclease H domain, inhibit the enzymatic activities of IN in vitro. The former peptide inhibits all three IN-associated activities (3′-end processing, strand transfer, and disintegration), whereas the latter one inhibits primarily the first two functions. We showed the importance of the sequences and peptide length for the effective inhibition of IN activities. Binding assays of the peptides to IN (with no DNA substrate present) indicated that the two inhibitory peptides (as well as several non-inhibitory peptides) interact directly with IN. Moreover, the isolated catalytic core domain of IN also interacted directly with the two inhibitory peptides. Nevertheless, only peptide 4286 can inhibit the disintegration activity associated with the IN core domain, because this activity is the only one exhibited by this domain. This result was expected from the lack of inhibition of disintegration of full-length IN by peptide 4321. The data and the three-dimensional models presented suggested that the inhibition resulted from steric hindrance of the catalytic domain of IN. This information can substantially facilitate the development of novel drugs against HIV INs and thus contribute to the fight against AIDS.

Interaction of linear polyamines with negatively charged phospholipids: the effect of polyamine charge distance

2014 ◽  
Vol 395 (7-8) ◽  
pp. 769-778 ◽  
Author(s):  
Sebastian Finger ◽  
Christian Schwieger ◽  
Ahmad Arouri ◽  
Andreas Kerth ◽  
Alfred Blume
Keyword(s):  
Phase Transition ◽  
Lipid Membranes ◽  
Electrostatic Interactions ◽  
Lipid Vesicles ◽  
Molecular Crowding ◽  
Domain Formation ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Methylene Groups ◽  
Gel Phase

Abstract The binding of cationic polyamines to negatively charged lipid membranes is driven by electrostatic interactions and additional hydrophobic contributions. We investigated the effect of polyamines with different number of charges and charge separation on the phase transition behavior of vesicles of phosphatidylglycerols (dipalmitoylphosphatidylglycerol and dimyristoylphosphatidylglycerol) to differentiate between effects caused by the number of charges, the charge distance, and the hydrophobicity of the methylene spacer. Using differential scanning calorimetry and Fourier transform infrared spectroscopy complemented with monolayer experiments, we found that the binding constant of polyamines to negatively charged lipid vesicles depends as expected on the number of charges. However, for diamines, the effect of binding on the main phase transition of phosphatidylglycerols (PGs) is also strongly influenced by the charge distance between the ammonium groups in the backbone. Oligoamines with charges separated by two or three methylene groups bind more strongly and have larger stabilizing effects on the lipid gel phase of PGs. With multivalent polyamines, the appearance of several transition peaks points to effects of molecular crowding on the surface, i.e., binding of only two or three charges to the surface in the case of spermine, and possible concomitant domain formation.

scholarly journals Mechanical Properties and In Vitro Evaluation of Thermoplastic Polyurethane and Polylactic Acid Blend for Fabrication of 3D Filaments for Tracheal Tissue Engineering

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3087
Author(s):  
Asmak Abdul Samat ◽  
Zuratul Ain Abdul Hamid ◽  
Mariatti Jaafar ◽  
Badrul Hisham Yahaya
Keyword(s):  
Tissue Engineering ◽  
Polylactic Acid ◽  
Thermoplastic Polyurethane ◽  
Three Dimensional ◽  
Thermal Characteristics ◽  
Surgical Reconstruction ◽  
Scanning Calorimetry ◽  
3D Printed ◽  
Tracheal Tissue

Surgical reconstruction of extensive tracheal lesions is challenging. It requires a mechanically stable, biocompatible, and nontoxic material that gradually degrades. One of the possible solutions for overcoming the limitations of tracheal transplantation is a three-dimensional (3D) printed tracheal scaffold made of polymers. Polymer blending is one of the methods used to produce material for a trachea scaffold with tailored characteristics. The purpose of this study is to evaluate the mechanical and in vitro properties of a thermoplastic polyurethane (TPU) and polylactic acid (PLA) blend as a potential material for 3D printed tracheal scaffolds. Both materials were melt-blended using a single screw extruder. The morphologies (as well as the mechanical and thermal characteristics) were determined via scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, tensile test, and Differential Scanning calorimetry (DSC). The samples were also evaluated for their water absorption, in vitro biodegradability, and biocompatibility. It is demonstrated that, despite being not miscible, TPU and PLA are biocompatible, and their promising properties are suitable for future applications in tracheal tissue engineering.

Characterization of a reactive groove in HIV-1 capsid protein defined by an in vitro assembly inhibitor

2007 ◽  
Vol 2007 (Spring) ◽  
Author(s):  
Vanda Bartonova ◽  
Jana Sticht ◽  
Peter Sehr ◽  
Joe Lewis ◽  
Hans-Georg Kraeusslich
Keyword(s):  
Capsid Protein ◽  
In Vitro Assembly ◽  
Hiv 1
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