scholarly journals Self-Assembly in Ganglioside‒Phospholipid Systems: The Co-Existence of Vesicles, Micelles, and Discs

2019 ◽  
Vol 21 (1) ◽  
pp. 56 ◽  
Author(s):  
Enamul Haque Mojumdar ◽  
Carl Grey ◽  
Emma Sparr
Keyword(s):  
Self Assembly ◽  
Biological Systems ◽  
Strong Impact ◽  
Physiological Processes ◽  
Diffusion Nmr ◽  
Lipid Species ◽  
Small Disc ◽  
Lipid System ◽  
Acyl Chains ◽  
Complementary Techniques

Ganglioside lipids have been associated with several physiological processes, including cell signaling. They have also been associated with amyloid aggregation in Parkinson’s and Alzheimer’s disease. In biological systems, gangliosides are present in a mix with other lipid species, and the structure and properties of these mixtures strongly depend on the proportions of the different components. Here, we study self-assembly in model mixtures composed of ganglioside GM1 and a zwitterionic phospholipid, 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC). We characterize the structure and molecular dynamics using a range of complementary techniques, including cryo-TEM, polarization transfer solid state NMR, diffusion NMR, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and calorimetry. The main findings are: (1) The lipid acyl chains are more rigid in mixtures containing both lipid species compared to systems that only contain one of the lipids. (2) The system containing DOPC with 10 mol % GM1 contains both vesicles and micelles. (3) At higher GM1 concentrations, the sample is more heterogenous and also contains small disc-like or rod-like structures. Such a co-existence of structures can have a strong impact on the overall properties of the lipid system, including transport, solubilization, and partitioning, which can be crucial to the understanding of the role of gangliosides in biological systems.

Examining the structure of the mature amyloid fibril

2002 ◽  
Vol 30 (4) ◽  
pp. 521-525 ◽  
Author(s):  
O. S. Makin ◽  
L. C. Serpell
Keyword(s):  
Self Assembly ◽  
Rational Design ◽  
Amyloid Fibrils ◽  
Structural Information ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Fibre Diffraction ◽  
Complementary Techniques ◽  
Mature Fibril

The pathogenesis of the group of diseases known collectively as the amyloidoses is characterized by the deposition of insoluble amyloid fibrils. These are straight, unbranching structures about 70–120 å (1 å = 0.1 nm) in diameter and of indeterminate length formed by the self-assembly of a diverse group of normally soluble proteins. Knowledge of the structure of these fibrils is necessary for the understanding of their abnormal assembly and deposition, possibly leading to the rational design of therapeutic agents for their prevention or disaggregation. Structural elucidation is impeded by fibril insolubility and inability to crystallize, thus preventing the use of X-ray crystallography and solution NMR. CD, Fourier-transform infrared spectroscopy and light scattering have been used in the study of the mechanism of fibril formation. This review concentrates on the structural information about the final, mature fibril and in particular the complementary techniques of cryo-electron microscopy, solid-state NMR and X-ray fibre diffraction.

Interactions of the Antimicrobial Peptide Maculatin 1.1 and Analogues with Phospholipid Bilayers

2011 ◽  
Vol 64 (6) ◽  
pp. 798 ◽  
Author(s):  
David I. Fernandez ◽  
Marc-Antoine Sani ◽  
Frances Separovic
Keyword(s):  
Antimicrobial Peptide ◽  
Solid State Nmr ◽  
Acyl Chain ◽  
Head Group ◽  
Group Interactions ◽  
Bacterial Membranes ◽  
Helical Content ◽  
Lipid System ◽  
Acyl Chains ◽  
Mixed Bilayer

The interactions of the antimicrobial peptide, maculatin 1.1 (GLFGVLAKVAAHVVPAIAEHF-NH2) and two analogues, with model phospholipid membranes have been studied using solid-state NMR and circular dichroism spectroscopy. Maculatin 1.1 and the P15G and P15A analogues displayed minimal secondary structure in water, but with zwitterionic dimyristoylphosphatidylcholine (DMPC) vesicles displayed a significant increase in α-helical content. In mixed phospholipid vesicles of DMPC and anionic dimyristoylphosphatidylglycerol (DMPG), each peptide was highly structured with ~80% α-helical content. In DMPC vesicles, the native peptide displayed moderate head group interaction and significant perturbation of the lipid acyl chains. In DMPC/DMPG vesicles, maculatin 1.1 promoted formation of a DMPG-enriched phase and moderately increased disorder towards acyl chain ends of DMPC in the mixed bilayer. Both analogues showed reduced phospholipid head group interactions with DMPC but displayed significant interactions with the mixed lipid system. These effects support the preferential activity of these antimicrobial peptides for bacterial membranes.

scholarly journals Functional analyses of phosphatidylserine/PI(4)P exchangers with diverse lipid species and membrane contexts set unanticipated rules on lipid transfer

2021 ◽  
Author(s):  
Souade Ikhlef ◽  
Nicolas-Frédéric Lipp ◽  
Vanessa Delfosse ◽  
Nicolas Fuggetta ◽  
William Bourguet ◽  
...  
Keyword(s):  
Lipid Transfer ◽  
Oxysterol Binding Protein ◽  
Lipid Exchange ◽  
Exchange Processes ◽  
Lipid Species ◽  
Acyl Chains ◽  
Phosphatidylinositol 4 ◽  
Functional Analyses ◽  
Related Proteins

Several members of the oxysterol-binding protein-related proteins (ORPs)/oxysterol-binding homology (Osh) family exchange phosphatidylserine (PS) and phosphatidylinositol 4-phosphate (PI(4)P) at the endoplasmic reticulum/plasma membrane (PM) interface. It is unclear whether they preferentially exchange PS and PI(4)P with specific acyl chains to tune the features of the PM, whether they use phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) instead of PI(4)P for exchange processes and whether their activity is influenced by the association of PS with sterol in the PM. Here, we measured in vitro how the yeast Osh6p and human ORP8 transported diverse PS and PI(4)P subspecies, including major cellular species, between membranes. We established how their activity is impacted by the length and unsaturation degree of these lipids. Surprisingly, the speed at which they individually transfer these ligands inversely depends on their affinity for them. To be fast, the transfer of high-affinity ligands requires an exchange with a counterligand of equivalent affinity. Besides, we determined that Osh6p and ORP8 cannot use PI(4,5)P2 for intracellular lipid exchange, as they have a low affinity for this lipid compared to PI(4)P, and do not transfer more PS into sterol-rich membranes. This study provides insights into PS/PI(4)P exchangers and sets unanticipated rules on how the activity of lipid transfer proteins relates to their affinity for ligands.

Organization and Self-Assembly Away from Equilibrium: Toward Thermodynamic Design Principles

2021 ◽  
Vol 12 (1) ◽  
pp. 273-290
Author(s):  
Michael Nguyen ◽  
Yuqing Qiu ◽  
Suriyanarayanan Vaikuntanathan
Keyword(s):  
Energy Dissipation ◽  
Self Assembly ◽  
Biological Systems ◽  
Design Principles ◽  
Nonequilibrium Process ◽  
Nanoscale Materials ◽  
Stochastic Thermodynamics ◽  
Synthetic Materials ◽  
Starting Point

Studies of biological systems and materials, together with recent experimental and theoretical advances in colloidal and nanoscale materials, have shown how nonequilibrium forcing can be used to modulate organization in many novel ways. In this review, we focus on how an accounting of energy dissipation, using the tools of stochastic thermodynamics, can constrain and provide intuition for the correlations and configurations that emerge in a nonequilibrium process. We anticipate that the frameworks reviewed here can provide a starting point to address some of the unique phenomenology seen in biophysical systems and potentially replicate them in synthetic materials.

scholarly journals Prebiotic oligomerization and self-assembly of structurally diverse xenobiological monomers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kuhan Chandru ◽  
Tony Z. Jia ◽  
Irena Mamajanov ◽  
Niraja Bapat ◽  
H. James Cleaves
Keyword(s):  
Nucleic Acids ◽  
Self Assembly ◽  
Cyclic Nucleotide ◽  
Biological Systems ◽  
Kinetic Control ◽  
Mild Conditions ◽  
Self Organized ◽  
Ring Structures ◽  
Drying Conditions ◽  
Stable Ring

Abstract Prebiotic chemists often study how modern biopolymers, e.g., peptides and nucleic acids, could have originated in the primitive environment, though most contemporary biomonomers don’t spontaneously oligomerize under mild conditions without activation or catalysis. However, life may not have originated using the same monomeric components that it does presently. There may be numerous non-biological (or “xenobiological”) monomer types that were prebiotically abundant and capable of facile oligomerization and self-assembly. Many modern biopolymers degrade abiotically preferentially via processes which produce thermodynamically stable ring structures, e.g. diketopiperazines in the case of proteins and 2′, 3′-cyclic nucleotide monophosphates in the case of RNA. This weakness is overcome in modern biological systems by kinetic control, but this need not have been the case for primitive systems. We explored here the oligomerization of a structurally diverse set of prebiotically plausible xenobiological monomers, which can hydrolytically interconvert between cyclic and acyclic forms, alone or in the presence of glycine under moderate temperature drying conditions. These monomers included various lactones, lactams and a thiolactone, which varied markedly in their stability, propensity to oligomerize and apparent modes of initiation, and the oligomeric products of some of these formed self-organized microscopic structures which may be relevant to protocell formation.

Modeling and Simulation of Biological Self-Assembly Structures from Nanoscale Entities

2007 ◽  
Vol 7 (12) ◽  
pp. 4248-4253 ◽  
Author(s):  
Ramana M. Pidaparti ◽  
David Primeaux ◽  
Brandon Saunders
Keyword(s):  
Modeling And Simulation ◽  
Thermodynamic Equilibrium ◽  
Self Assembly ◽  
Biological Systems ◽  
The Self ◽  
Eukaryotic Cells ◽  
Assembly Process ◽  
Equilibrium Conditions ◽  
Preliminary Results ◽  
Computational Methodology

Many natural and biological systems are formed by the process of molecular self-assembly. Molecular self-assembly is defined as the spontaneous organization of molecules under thermodynamic equilibrium conditions into structurally well defined and rather stable arrangements. In this paper, we developed a novel computational methodology to investigate the self-assembly process of simple 1-D structures representing protein monomers into long filaments, rings, pyramids, bundles, etc. Based on the preliminary results obtained, the methodology was extended to mimic the microtubule self-assembly, which occurs in all eukaryotic cells.

The Embodiment of Synthetic Emotion

2015 ◽  
pp. 204-212
Author(s):  
Carlos Herrera ◽  
M.G. Sánchez-Escribano ◽  
Ricardo Sanz
Keyword(s):  
Information Processing ◽  
Biological Systems ◽  
Control Action ◽  
Cognitive Economy ◽  
Interaction Dynamics ◽  
Actual Role ◽  
Physiological Processes ◽  
Novel Approach ◽  
Fundamental Phenomenon

Emotions are fundamentally embodied phenomena - but what exactly does this mean? And how is embodiment relevant for synthetic emotion? The specific role of embodied processes in the organisation of cognition and behaviour in biological systems is too complex to analyse without abstracting away the vast majority of variables. Robotic approaches have thus ignored physiological processes. At most, they hypothesise that homeostatic processes play a role in the cognitive economy of the agent – “gut feeling” is the embodied phenomenon to be modelled. Physiological processes play an actual role in the control of behaviour and interaction dynamics beyond information-processing. In this chapter, the authors introduce a novel approach to emotion synthesis based on the notion of morphofunctionality: the capacity to modulate the function of subsystems, changing the overall functionality of the system. Morphofunctionality provides robots with the capacity to control action readiness, and this in turn is a fundamental phenomenon for the emergence of emotion.

Functional self-assembling polypeptide bionanomaterials

2012 ◽  
Vol 40 (4) ◽  
pp. 629-634 ◽  
Author(s):  
Tibor Doles ◽  
Sabina Božič ◽  
Helena Gradišar ◽  
Roman Jerala
Keyword(s):  
Self Assembly ◽  
Biological Systems ◽  
Three Dimensional ◽  
Coiled Coil ◽  
Chemical Properties ◽  
Building Blocks ◽  
External Signal ◽  
Form Complex ◽  
Cell Factories ◽  
Self Assembling

Bionanotechnology seeks to modify and design new biopolymers and their applications and uses biological systems as cell factories for the production of nanomaterials. Molecular self-assembly as the main organizing principle of biological systems is also the driving force for the assembly of artificial bionanomaterials. Protein domains and peptides are particularly attractive as building blocks because of their ability to form complex three-dimensional assemblies from a combination of at least two oligomerization domains that have the oligomerization state of at least two and three respectively. In the present paper, we review the application of polypeptide-based material for the formation of material with nanometre-scale pores that can be used for the separation. Use of antiparallel coiled-coil dimerization domains introduces the possibility of modulation of pore size and chemical properties. Assembly or disassembly of bionanomaterials can be regulated by an external signal as demonstrated by the coumermycin-induced dimerization of the gyrase B domain which triggers the formation of polypeptide assembly.

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