scholarly journals DNA Duplexes with Hydrophobic Modifications Inhibit Fusion between HIV-1 and Cell Membranes

2013 ◽  
Vol 57 (10) ◽  
pp. 4963-4970 ◽  
Author(s):  
Liang Xu ◽  
Lifeng Cai ◽  
Xueliang Chen ◽  
Xifeng Jiang ◽  
Huihui Chong ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Cell Membranes ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
New Drugs ◽  
Heptad Repeat ◽  
Dna Duplexes ◽  
Dna Duplex ◽  
Modified Dna ◽  
Hiv 1

ABSTRACTDiscovery of new drugs for the treatment of AIDS typically possessing unique structures associated with novel mechanisms of action has been of great importance due to the quick drug-resistant mutations of HIV-1 strains. The work presented in this report describes a novel class of DNA duplex-based HIV-1 fusion inhibitors. Hydrophobic groups were introduced into a DNA duplex skeleton either at one end, at both ends, or in the middle. These modified DNA duplexes inhibited fusion between HIV-1 and human cell membranes at micro- or submicromolar concentrations. Respective inhibitors adopted an aptamer pattern instead of a base-pairing interaction pattern. Structure-activity relationship studies of the respective DNA duplexes showed that the rigid and negatively charged DNA skeletons, in addition to the presence of hydrophobic groups, were crucial to the anti-HIV-1 activity of these compounds. A fluorescent resonance energy transfer (FRET)-based inhibitory assay showed that these duplex inhibitors interacted with the primary pocket in the gp41 N-terminal heptad repeat (NHR) instead of interacting with the lipid bilayers.

scholarly journals Topological analysis of the gp41 MPER on lipid bilayers relevant to the metastable HIV-1 envelope prefusion state

2019 ◽  
Vol 116 (45) ◽  
pp. 22556-22566 ◽  
Author(s):  
Yi Wang ◽  
Pavanjeet Kaur ◽  
Zhen-Yu J. Sun ◽  
Mostafa A. Elbahnasawy ◽  
Zahra Hayati ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Neutralizing Antibodies ◽  
Structural Changes ◽  
Transmembrane Domain ◽  
Topological Analysis ◽  
Heptad Repeat ◽  
Structural Topology ◽  
Paramagnetic Resonance ◽  
Viral Membrane ◽  
Hiv 1

The membrane proximal external region (MPER) of HIV-1 envelope glycoprotein (gp) 41 is an attractive vaccine target for elicitation of broadly neutralizing antibodies (bNAbs) by vaccination. However, current details regarding the quaternary structural organization of the MPER within the native prefusion trimer [(gp120/41)3] are elusive and even contradictory, hindering rational MPER immunogen design. To better understand the structural topology of the MPER on the lipid bilayer, the adjacent transmembrane domain (TMD) was appended (MPER-TMD) and studied. Membrane insertion of the MPER-TMD was sensitive both to the TMD sequence and cytoplasmic residues. Antigen binding of MPER-specific bNAbs, in particular 10E8 and DH511.2_K3, was significantly impacted by the presence of the TMD. Furthermore, MPER-TMD assembly into 10-nm diameter nanodiscs revealed a heterogeneous membrane array comprised largely of monomers and dimers, as enumerated by bNAb Fab binding using single-particle electron microscopy analysis, arguing against preferential trimeric association of native MPER and TMD protein segments. Moreover, introduction of isoleucine mutations in the C-terminal heptad repeat to induce an extended MPER α-helical bundle structure yielded an antigenicity profile of cell surface-arrayed Env variants inconsistent with that found in the native prefusion state. In line with these observations, electron paramagnetic resonance analysis suggested that 10E8 inhibits viral membrane fusion by lifting the MPER N-terminal region out of the viral membrane, mandating the exposure of residues that would be occluded by MPER trimerization. Collectively, our data suggest that the MPER is not a stable trimer, but rather a dynamic segment adapted for structural changes accompanying fusion.

Daunomycin delivery by ultrasmall graphene quantum dots to DNA duplexes: understanding the dynamics by resonance energy transfer

2020 ◽  
Vol 8 (42) ◽  
pp. 9756-9763
Author(s):  
Riya Sinha ◽  
Pradipta Purkayastha
Keyword(s):  
Quantum Dots ◽  
Energy Transfer ◽  
Graphene Quantum Dots ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Dna Duplexes ◽  
Π Stacking

Crystalline graphene quantum dots are shown to carry daunomycin to DNA via π–π stacking with the planar anthracenyl moiety of the drug.

scholarly journals Structure dynamics of HIV-1 Env trimers on native virions engaged with living T cells

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Irene Carlon-Andres ◽  
Tomas Malinauskas ◽  
Sergi Padilla-Parra
Keyword(s):  
T Cells ◽  
Single Molecule ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Fluorescence Lifetime Imaging ◽  
Bona Fide ◽  
Hiv 1

AbstractThe HIV-1 envelope glycoprotein (Env) mediates viral entry into the host cell. Although the highly dynamic nature of Env intramolecular conformations has been shown with single molecule spectroscopy in vitro, the bona fide Env intra- and intermolecular mechanics when engaged with live T cells remains unknown. We used two photon fast fluorescence lifetime imaging detection of single-molecule Förster Resonance Energy Transfer occurring between fluorescent labels on HIV-1 Env on native virions. Our observations reveal Env dynamics at two levels: transitions between different intramolecular conformations and intermolecular interactions between Env within the viral membrane. Furthermore, we show that three broad neutralizing anti-Env antibodies directed to different epitopes restrict Env intramolecular dynamics and interactions between adjacent Env molecules when engaged with living T cells. Importantly, our results show that Env-Env interactions depend on efficient virus maturation, and that is disrupted upon binding of Env to CD4 or by neutralizing antibodies. Thus, this study illuminates how different intramolecular conformations and distribution of Env molecules mediate HIV-1 Env–T cell interactions in real time and therefore might control immune evasion.

Factor Xa Control of the Extrinsic Pathway: A Different View of the Regulation of Coagulation.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 546-546
Author(s):  
James J. Hathcock ◽  
Elena Rusinova ◽  
Yale Nemerson
Keyword(s):  
Tissue Factor ◽  
Lipid Bilayers ◽  
Membrane Surface ◽  
Resonance Energy Transfer ◽  
Factor Xa ◽  
Resonance Energy ◽  
Stochastic Simulations ◽  
Factor X ◽  
Binding Studies ◽  
Extrinsic Pathway

Abstract The activation of factor X by Tissue Factor(TF):VIIa on a membrane surface is one of the principal events in the initiation of coagulation. We have previously shown and presently confirm that reactions initiated by TF:VIIa do not typically result in the complete activation of substrate, but rather some intermediate level of fX activation. Excess phospholipid has complex effects on the TF:VIIa reaction, resulting in either inhibition, due to substrate depletion, or acceleration, by virtue of binding fXa. This complexity results in unavoidable ambiguities in interpretation of all previous reports. To tease apart these complexities, we have used benzamidine-sepharose that only binds fXa and not fX. We now show that the reaction product, fXa, can impede, and in fact, completely inhibit TF:VIIa activity. We monitored progress curves of fX activation by TF:VIIa in the presence and absence of benzamidine beads, which specifically partition the reaction product away from the TF:VIIa complexes. In the presence of these benzamidine beads, the activation rate of fX increased by 60% confirming that removal of fXa enhances tissue factor activity. Moreover, binding studies of fXa to TF-phospholipid surfaces indicate that the surface occupancy by fXa regulates TF:VIIa activity. Surface occupancy was evaluated by Total Internal Reflectance (on macroscopic lipid bilayers) and Fluorescence Resonance Energy Transfer (phospholipid vesicles). Our measurements of the off-rate of fXa (0.06–0.08 /s) are similar to some literature values, but differ by up to 500-fold from others. Stochastic simulations of TF:VIIa kinetics on phospholipid surfaces confirm that product leaving rates strongly regulate the observed experimental kinetics. Our approach indicates that current models of coagulation need to be altered to accommodate product surface occupancy. Indeed, if fXa occupancy is ignored, as is generally the case, the models simply cannot reflect reality.

scholarly journals Modulation of physiological and pathological activities of lysozyme by biological membranes

2012 ◽  
Vol 17 (3) ◽  
Author(s):  
Valeriya Trusova
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Dynamic Properties ◽  
Biological Activities ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Lipid Vesicles ◽  
Bacterial Cells ◽  
Oligomeric Protein ◽  
Wide Range

AbstractThe molecular details of interactions between lipid membranes and lysozyme (Lz), a small polycationic protein with a wide range of biological activities, have long been the focus of numerous studies. The biological consequences of this process are considered to embrace at least two aspects: i) correlation between antimicrobial and membranotropic properties of this protein, and ii) lipid-mediated Lz amyloidogenesis. The mechanisms underlying the lipid-assisted protein fibrillogenesis and membrane disruption exerted by Lz in bacterial cells are believed to be similar. The present investigation was undertaken to gain further insight into Lz-lipid interactions and explore the routes by which Lz exerts its antimicrobial and amyloidogenic actions. Binding and Förster resonance energy transfer studies revealed that upon increasing the content of anionic lipids in lipid vesicles, Lz forms aggregates in a membrane environment. Total internal reflection fluorescence microscopy and pyrene excimerization reaction were employed to study the effect of Lz on the structural and dynamic properties of lipid bilayers. It was found that Lz induces lipid demixing and reduction of bilayer free volume, the magnitude of this effect being much more pronounced for oligomeric protein.

Resonance Energy Transfer in DNA Duplexes Labeled with Localized Dyes

2014 ◽  
Vol 118 (50) ◽  
pp. 14555-14565 ◽  
Author(s):  
Paul D. Cunningham ◽  
Ani Khachatrian ◽  
Susan Buckhout-White ◽  
Jeffrey R. Deschamps ◽  
Ellen R. Goldman ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Dna Duplexes
Sign in / Sign up

Export Citation Format

Share Document