scholarly journals Coexistence of long and short DNA constructs within adhesion plaques

2020 ◽  
Author(s):  
Long Li ◽  
Mohammad Arif Kamal ◽  
Henning Stumpf ◽  
Franck Thibaudau ◽  
Kheya Sengupta ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Optical Resolution ◽  
Simultaneous Action ◽  
Supported Lipid Bilayers ◽  
Physical Mechanisms ◽  
Domain Structures ◽  
Membrane Interfaces ◽  
A Cell ◽  
Physical Effects ◽  
Relative Differences

Adhesion domains forming at the membrane interfaces between two cells or a cell and the ex-tracellular matrix commonly involve multiple proteins bridges. However, the physical mechanisms governing the domain structures are not yet fully resolved. Here we present a joint experimental and theoretical study of a mimetic model-system, based on giant unilammelar vesicles interacting with supported lipid bilayers, with which the underlying physical effects can be clearly identified. In our case, adhesion is induced by simultaneous action of DNA linkers with two different lengths. We study the organization of bridges into domains as a function of relative fraction of long and short DNA constructs. Irrespective of the composition, we systematically find adhesion domains with coexisting DNA bridge types, despite their relative differences in length of 9 nm. However, at short length scales, below the optical resolution of the microscope, simulations suggest the formation of nanodomains by the minority fraction. The nano-aggregation is more significant for long bridges, which are also more stable, even though the enthalpy of membrane insertion is the same for both species.

scholarly journals Micron-scale plasma membrane curvature is recognized by the septin cytoskeleton

2016 ◽  
Vol 213 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Andrew A. Bridges ◽  
Maximilian S. Jentzsch ◽  
Patrick W. Oakes ◽  
Patricia Occhipinti ◽  
Amy S. Gladfelter
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Fundamental Property ◽  
Membrane Curvature ◽  
Supported Lipid Bilayers ◽  
Nanometer Scale ◽  
Local Shape ◽  
A Cell ◽  
Developmental Conditions ◽  
In Cells

Cells change shape in response to diverse environmental and developmental conditions, creating topologies with micron-scale features. Although individual proteins can sense nanometer-scale membrane curvature, it is unclear if a cell could also use nanometer-scale components to sense micron-scale contours, such as the cytokinetic furrow and base of neuronal branches. Septins are filament-forming proteins that serve as signaling platforms and are frequently associated with areas of the plasma membrane where there is micron-scale curvature, including the cytokinetic furrow and the base of cell protrusions. We report here that fungal and human septins are able to distinguish between different degrees of micron-scale curvature in cells. By preparing supported lipid bilayers on beads of different curvature, we reconstitute and measure the intrinsic septin curvature preference. We conclude that micron-scale curvature recognition is a fundamental property of the septin cytoskeleton that provides the cell with a mechanism to know its local shape.

scholarly journals Electrostatics, Hydrogen Bonding, and Molecular Structure at Polycation and Peptide:Lipid Membrane Interfaces

2019 ◽  
Author(s):  
Naomi Dalchand ◽  
Qiang Cui ◽  
Franz Geiger
Keyword(s):  
Lipid Bilayers ◽  
Bacterial Resistance ◽  
Second Harmonic ◽  
High Surface ◽  
Ion Pairs ◽  
Supported Lipid Bilayers ◽  
Sum Frequency ◽  
Charge Densities ◽  
Line Shapes ◽  
Membrane Interfaces

Polycation and peptide modified surfaces represent opportunities for developing potentially novel biocidal materials in a growing effort to combat bacterial resistance to traditional bactericides. It is well known that the positive charge of these compounds is crucial to their function in biofouling prevention and as antimicrobials, however, methods for quantifying the number of positive charges on surface-bound polycations and peptides are necessary in order to predict, control, and optimize the design and therefore, the utility of these compounds. This Spotlight on Applications reports on such an approach that combines second harmonic generation (SHG) spectroscopy, quartz crystal microbalance with dissipation monitoring (QCM-D), and atomistic simulations to obtain mechanistic insight into polycation-membrane interactions using supported lipid bilayers (SLBs) as our model system. We find that at high surface coverage, the large polycations we surveyed feature a considerably smaller percentage of ionization when compared to the smaller polycations and peptides. At these high charge densities, we suspect a pKa shift of the charged groups to lower charge-charge repulsion as well as the formation of a loop-like conformation such that less monomeric units form contact-ion pairs with the bilayer. Our sum frequency generation (SFG) spectroscopy results complement our understanding of the polycation-membrane interaction. At a high density of the polycation poly (allylamine hydrochloride) (PAH), second-order spectral line shapes are consistent with the expulsion of interfacial water molecules possibly due to contact-ion pair formation between PAH and the lipid bilayer. This finding could be essential for understanding the underlying first steps of cell lysis and penetration by polycations and should be explored further.<br>

scholarly journals Enhancing the antitumor efficacy of a cell-surface death ligand by covalent membrane display

2015 ◽  
Vol 112 (18) ◽  
pp. 5679-5684 ◽  
Author(s):  
Pradeep M. Nair ◽  
Heather Flores ◽  
Alvin Gogineni ◽  
Scot Marsters ◽  
David A. Lawrence ◽  
...  
Keyword(s):  
Cell Surface ◽  
Lipid Bilayers ◽  
Therapeutic Potential ◽  
Supported Lipid Bilayers ◽  
Surface Attachment ◽  
Tnf Superfamily ◽  
Membrane Attachment ◽  
A Cell ◽  
Surface Ligand

TNF superfamily death ligands are expressed on the surface of immune cells and can trigger apoptosis in susceptible cancer cells by engaging cognate death receptors. A recombinant soluble protein comprising the ectodomain of Apo2 ligand/TNF-related apoptosis-inducing ligand (Apo2L/TRAIL) has shown remarkable preclinical anticancer activity but lacked broad efficacy in patients, possibly owing to insufficient exposure or potency. We observed that antibody cross-linking substantially enhanced cytotoxicity of soluble Apo2L/TRAIL against diverse cancer cell lines. Presentation of the ligand on glass-supported lipid bilayers enhanced its ability to drive receptor microclustering and apoptotic signaling. Furthermore, covalent surface attachment of Apo2L/TRAIL onto liposomes—synthetic lipid-bilayer nanospheres—similarly augmented activity. In vivo, liposome-displayed Apo2L/TRAIL achieved markedly better exposure and antitumor activity. Thus, covalent synthetic-membrane attachment of a cell-surface ligand enhances efficacy, increasing therapeutic potential. These findings have translational implications for liposomal approaches as well as for Apo2L/TRAIL and other clinically relevant TNF ligands.

scholarly journals Electrostatics, Hydrogen Bonding, and Molecular Structure at Polycation and Peptide:Lipid Membrane Interfaces

2019 ◽  
Author(s):  
Naomi Dalchand ◽  
Qiang Cui ◽  
Franz Geiger
Keyword(s):  
Lipid Bilayers ◽  
Bacterial Resistance ◽  
Second Harmonic ◽  
High Surface ◽  
Ion Pairs ◽  
Supported Lipid Bilayers ◽  
Sum Frequency ◽  
Charge Densities ◽  
Line Shapes ◽  
Membrane Interfaces

Polycation and peptide modified surfaces represent opportunities for developing potentially novel biocidal materials in a growing effort to combat bacterial resistance to traditional bactericides. It is well known that the positive charge of these compounds is crucial to their function in biofouling prevention and as antimicrobials, however, methods for quantifying the number of positive charges on surface-bound polycations and peptides are necessary in order to predict, control, and optimize the design and therefore, the utility of these compounds. This Spotlight on Applications reports on such an approach that combines second harmonic generation (SHG) spectroscopy, quartz crystal microbalance with dissipation monitoring (QCM-D), and atomistic simulations to obtain mechanistic insight into polycation-membrane interactions using supported lipid bilayers (SLBs) as our model system. We find that at high surface coverage, the large polycations we surveyed feature a considerably smaller percentage of ionization when compared to the smaller polycations and peptides. At these high charge densities, we suspect a pKa shift of the charged groups to lower charge-charge repulsion as well as the formation of a loop-like conformation such that less monomeric units form contact-ion pairs with the bilayer. Our sum frequency generation (SFG) spectroscopy results complement our understanding of the polycation-membrane interaction. At a high density of the polycation poly (allylamine hydrochloride) (PAH), second-order spectral line shapes are consistent with the expulsion of interfacial water molecules possibly due to contact-ion pair formation between PAH and the lipid bilayer. This finding could be essential for understanding the underlying first steps of cell lysis and penetration by polycations and should be explored further.<br>

Influence of Brain Gangliosides on the Formation and Properties of Supported Lipid Bilayers for Binding Kinetics Studies

2018 ◽  
Author(s):  
Luke Jordan ◽  
Nathan Wittenberg
Keyword(s):  
Lipid Bilayers ◽  
Binding Kinetics ◽  
Supported Lipid Bilayers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Supported Lipid Bilayer ◽  
Head Groups ◽  
Lipid Diffusion ◽  
Kinetics Of ◽  
Brain Gangliosides

This is a comprehensive study of the effects of the four major brain gangliosides (GM1, GD1b, GD1a, and GT1b) on the adsorption and rupture of phospholipid vesicles on SiO2 surfaces for the formation of supported lipid bilayer (SLB) membranes. Using quartz crystal microbalance with dissipation monitoring (QCM-D) we show that gangliosides GD1a and GT1b significantly slow the SLB formation process, whereas GM1 and GD1b have smaller effects. This is likely due to the net ganglioside charge as well as the positions of acidic sugar groups on ganglioside glycan head groups. Data is included that shows calcium can accelerate the formation of ganglioside-rich SLBs. Using fluorescence recovery after photobleaching (FRAP) we also show that the presence of gangliosides significantly reduces lipid diffusion coefficients in SLBs in a concentration-dependent manner. Finally, using QCM-D and GD1a-rich SLB membranes we measure the binding kinetics of an anti-GD1a antibody that has similarities to a monoclonal antibody that is a hallmark of a variant of Guillain-Barre syndrome.

scholarly journals Silica nanoparticle supported lipid bilayers for gene delivery

2009 ◽  
pp. 5100 ◽  
Author(s):  
Juewen Liu ◽  
Alison Stace-Naughton ◽  
C. Jeffrey Brinker
Keyword(s):  
Gene Delivery ◽  
Lipid Bilayers ◽  
Silica Nanoparticle ◽  
Supported Lipid Bilayers

scholarly journals Formation of Supported Lipid Bilayers Derived from Vesicles of Various Compositional Complexity on Conducting Polymer/Silica Substrates

Langmuir ◽  
2021 ◽  
Author(s):  
Hanna Ulmefors ◽  
Josefin Nissa ◽  
Hudson Pace ◽  
Olov Wahlsten ◽  
Anders Gunnarsson ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Conducting Polymer ◽  
Supported Lipid Bilayers ◽  
Silica Substrates

scholarly journals Delivery of Ricin Toxin A-Chain by Peptide-Targeted Mesoporous Silica Nanoparticle-Supported Lipid Bilayers

2012 ◽  
Vol 1 (3) ◽  
pp. 348-353 ◽  
Author(s):  
Katharine Epler ◽  
David Padilla ◽  
Genevieve Phillips ◽  
Peter Crowder ◽  
Robert Castillo ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Lipid Bilayers ◽  
Silica Nanoparticle ◽  
Supported Lipid Bilayers ◽  
Toxin A ◽  
Mesoporous Silica Nanoparticle ◽  
Ricin Toxin ◽  
A Chain
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