scholarly journals Lipid membranes trigger misfolding and self-assembly of amyloid β 42 protein into aggregates

2019 ◽  
Author(s):  
Siddhartha Banerjee ◽  
Mohtadin Hashemi ◽  
Karen Zagorski ◽  
Yuri L. Lyubchenko
Keyword(s):  
Self Assembly ◽  
Lipid Membranes ◽  
Membrane Surface ◽  
Amyloid Β ◽  
Test Tube ◽  
Aggregation Process ◽  
Self Assembling ◽  
Nanoscale Aggregates

AbstractThe assembly of polypeptides and proteins into nanoscale aggregates is a phenomenon observed in a vast majority of proteins. Importantly, aggregation of amyloid β (Aβ) proteins is considered as a major cause for the development of Alzheimer’s disease. The process depends on various conditions and typical test-tube experiments require high protein concentration that complicates the translation of results obtained in vitro to understanding the aggregation process in vivo. Here we demonstrate that Aβ42 monomers at the membrane bilayer are capable of self-assembling into aggregates at physiologically low concentrations, and the membrane in this aggregation process plays a role of a catalyst. We applied all-atom molecular dynamics to demonstrate that the interaction with the membrane surface dramatically changes the conformation of Aβ42 protein. As a result, the misfolded Aβ42 rapidly assembles into dimers, trimers and tetramers, so the on-surface aggregation is the mechanism by which amyloid oligomers are produced and spread.

scholarly journals Interaction of Aβ42 with Membranes Triggers the Self-Assembly into Oligomers

2020 ◽  
Vol 21 (3) ◽  
pp. 1129 ◽  
Author(s):  
Siddhartha Banerjee ◽  
Mohtadin Hashemi ◽  
Karen Zagorski ◽  
Yuri L. Lyubchenko
Keyword(s):  
Self Assembly ◽  
Membrane Surface ◽  
Amyloid Β ◽  
The Self ◽  
Bulk Solution ◽  
Aggregation Process ◽  
Physiological Concentration ◽  
Dynamics Simulations

The self-assembly of amyloid β (Aβ) proteins into oligomers is the major pathogenic event leading to Alzheimer’s disease (AD). Typical in vitro experiments require high protein concentrations, whereas the physiological concentration of Aβ is in the picomolar to low nanomolar range. This complicates the translation of results obtained in vitro to understanding the aggregation process in vivo. Here, we demonstrate that Aβ42 self-assembles into aggregates on membrane bilayers at low nanomolar concentrations - a pathway in which the membrane plays the role of a catalyst. Additionally, physiological ionic conditions (150 mM NaCl) significantly enhance on-membrane aggregation, leading to the rapid formation of oligomers. The self-assembly process is reversible, so assembled aggregates can dissociate from the membrane surface into the bulk solution to further participate in the aggregation process. Molecular dynamics simulations demonstrate that the transient membrane-Aβ interaction dramatically changes the protein conformation, facilitating the assembly of dimers. The results indicate peptide–membrane interaction is the critical step towards oligomer formation at physiologically low protein concentrations.

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 Reproducibility Problems of Amyloid-β Self-Assembly and How to Deal With Them

2021 ◽  
Vol 8 ◽  
Author(s):  
Peter Faller ◽  
Christelle Hureau
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Self Assembly ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Test Tube ◽  
The Self ◽  
Aggregation Process ◽  
Self Assembled

The self-assembly of peptides and proteins into amyloid fibrils and other aggregates are linked to several diseases. One of the most studied cases is the peptide amyloid-β (Aβ), found self-assembled in Alzheimer's disease patients' brains. In test tubes, assays with chemically synthesized or recombinant Aβ are widely investigated to understand the aggregation process and to find modulators, which could be of therapeutic interest. Experience over more than a decade in our laboratory through discussions with colleagues, expertly studying the literature, and as reviewers revealed to us the widely encountered difficulty to control the aggregation and obtain reproducible results in the test tube. However, this issue is scarcely reported and discussed in the publications, which we think hampers strongly the progress in this field and can deceive newcomers. Here, we describe the difficulty and potential reasons to obtain reproducible aggregation data and propose some guidelines for working with it.

Molecular self-assembly of a tyroservatide-derived octapeptide and hydroxycamptothecin for enhanced therapeutic efficacy

Nanoscale ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 5094-5102
Author(s):  
Jing Liu ◽  
Can Wu ◽  
Guoru Dai ◽  
Feng Feng ◽  
Yuquan Chi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Self Assembly ◽  
Therapeutic Efficacy ◽  
Self Assembling

A pure l-amino acid-based molecular hydrogel was designed through conjugation of an anticancer tripeptide tyroservatide (YSV) with a self-assembling moiety, which enhanced therapeutic efficacy of both YSV and hydroxycamptothecin in vitro and in vivo.

Aggregation of amyloids in a cellular context: modelling and experiment

2011 ◽  
Vol 438 (3) ◽  
pp. 415-426 ◽  
Author(s):  
Ran Friedman
Keyword(s):  
Lipid Membranes ◽  
Amyloid Β ◽  
Integrative Approach ◽  
Aggregation Process ◽  
Amyloid Aggregation ◽  
Molecular Events ◽  
Context Modelling ◽  
Wide Range ◽  
Recent Developments

Amyloid-related diseases are a group of illnesses in which an abnormal accumulation of proteins into fibrillar structures is evident. Results from a wide range of studies, ranging from identification of amyloid-β dimers in the brain to biophysical characterization of the interactions between amyloidogenic peptides and lipid membranes during fibril growth shed light on the initial events which take place during amyloid aggregation. Accounts of fibril disaggregation and formation of globular aggregates due to interactions with lipids or fatty acids further demonstrate the complexity of the aggregation process and the difficulty to treat amyloid-related diseases. There is an inherent difficulty in generalizing from studies of aggregation in vitro, but the involvement of too many cellular components limits the ability to follow amyloid aggregation in a cellular (or extracellular) context. Fortunately, the development of experimental methods to generate stable globular aggregates suggests new means of studying the molecular events associated with amyloid aggregation. Furthermore, simulation studies enable deeper understanding of the experimental results and provide useful predictions that can be tested in the laboratory. Computer simulations can nowadays provide molecular or even atomistic details that are experimentally not available or very difficult to obtain. In the present review, recent developments on modelling and experiments of amyloid aggregation are reviewed, and an integrative account on how isolated interactions (as observed in vitro and in silico) combine during the course of amyloid-related diseases is presented. Finally, it is argued that an integrative approach is necessary to get a better understanding of the protein aggregation process.

Self-assembling RATEA16 peptide nanofiber designed for rapid hemostasis

2020 ◽  
Vol 8 (9) ◽  
pp. 1897-1905 ◽  
Author(s):  
Shuda Wei ◽  
Fangping Chen ◽  
Zhen Geng ◽  
Ruihua Cui ◽  
Yujiao Zhao ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Self Assembly ◽  
Solid Phase ◽  
Phase Method ◽  
Self Assembling ◽  
Solid Phase Method ◽  
Assembly Performance

In this study, we synthesized a novel polypeptide material, RATEA16, by the solid phase method, and investigated the secondary structure, self-assembly performance, gelation ability, biocompatibility and hemostatic efficiency in vitro and in vivo.

scholarly journals An S/T motif controls reversible oligomerization of the Hsp40 chaperone DNAJB6b through subtle reorganization of a β sheet backbone

2020 ◽  
Vol 117 (48) ◽  
pp. 30441-30450
Author(s):  
Theodoros K. Karamanos ◽  
Vitali Tugarinov ◽  
G. Marius Clore
Keyword(s):  
Self Assembly ◽  
Nmr Relaxation ◽  
Relaxation Dispersion ◽  
Nmr Studies ◽  
Self Assembling ◽  
Critical Residues ◽  
Nmr Methods ◽  
Β Sheet

Chaperone oligomerization is often a key aspect of their function. Irrespective of whether chaperone oligomers act as reservoirs for active monomers or exhibit a chaperoning function themselves, understanding the mechanism of oligomerization will further our understanding of how chaperones maintain the proteome. Here, we focus on the class-II Hsp40, human DNAJB6b, a highly efficient inhibitor of protein self-assembly in vivo and in vitro that forms functional oligomers. Using single-quantum methyl-based relaxation dispersion NMR methods we identify critical residues for DNAJB6b oligomerization in its C-terminal domain (CTD). Detailed solution NMR studies on the structure of the CTD showed that a serine/threonine-rich stretch causes a backbone twist in the N-terminal β strand, stabilizing the monomeric form. Quantitative analysis of an array of NMR relaxation-based experiments (including Carr–Purcell–Meiboom–Gill relaxation dispersion, off-resonanceR1ρprofiles, lifetime line broadening, and exchange-induced shifts) on the CTD of both wild type and a point mutant (T142A) within the S/T region of the first β strand delineates the kinetics of the interconversion between the major twisted-monomeric conformation and a more regular β strand configuration in an excited-state dimer, as well as exchange of both monomer and dimer species with high-molecular-weight oligomers. These data provide insights into the molecular origins of DNAJB6b oligomerization. Further, the results reported here have implications for the design of β sheet proteins with tunable self-assembling properties and pave the way to an atomic-level understanding of amyloid inhibition.

scholarly journals The extent of protein hydration dictates the preference for heterogeneous or homogeneous nucleation generating either parallel or antiparallel β-sheet α-synuclein aggregates

2020 ◽  
Author(s):  
José D. Camino ◽  
Pablo Gracia ◽  
Serene W. Chen ◽  
Jesús Sot ◽  
Igor de la Arada ◽  
...  
Keyword(s):  
Self Assembly ◽  
Lipid Membranes ◽  
Homogeneous Nucleation ◽  
Active Surface ◽  
Protein Hydration ◽  
Primary Nucleation ◽  
Cellular Microenvironments ◽  
Β Sheet

α-Synuclein amyloid self-assembly is the hallmark of a number of neurodegenerative disorders, including Parkinson’s disease, although there is still very limited understanding about the factors and mechanisms that trigger this process. Primary nucleation has been observed to be initiated in vitro at hydrophobic/hydrophilic interfaces by heterogeneous nucleation generating parallel β-sheet aggregates, although no such interfaces have yet been identified in vivo. In this work, we have discovered that α-synuclein can self-assemble into amyloid aggregates by homogeneous nucleation, without the need of an active surface, and with a preference for an antiparallel β-sheet arrangement. This particular structure has been previously proposed to be distinctive of stable toxic oligomers and we here demonstrate that it indeed represents the most stable structure of the preferred amyloid pathway triggered by homogeneous nucleation under limited hydration conditions, including those encountered inside α-synuclein droplets generated by liquid-liquid phase separation. In addition, our results highlight the key role that water plays not only in modulating the transition free energy of amyloid nucleation, and thus governing the initiation of the process, but also in dictating the type of preferred primary nucleation and the type of amyloid polymorph generated depending on the extent of protein hydration. These findings are particularly relevant in the context of in vivo α-synuclein aggregation where the protein can encounter a variety of hydration conditions in different cellular microenvironments, including the vicinity of lipid membranes or the interior of membraneless compartments, which could lead to the formation of remarkably different amyloid polymorphs by either heterogeneous or homogeneous nucleation.

scholarly journals Cell-free TXTL synthesis of infectious bacteriophage T4 in a single test tube reaction

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Mark Rustad ◽  
Allen Eastlund ◽  
Paul Jardine ◽  
Vincent Noireaux
Keyword(s):  
Self Assembly ◽  
Bacteriophage T4 ◽  
Test Tube ◽  
Great Promise ◽  
One Pot ◽  
Bottom Up ◽  
Self Assembling ◽  
Phage T4 ◽  
Biological Entities

Abstract The bottom-up construction of biological entities from genetic information provides a broad range of opportunities to better understand fundamental processes within living cells, as well as holding great promise for the development of novel biomedical applications. Cell-free transcription–translation (TXTL) systems have become suitable platforms to tackle such topics because they recapitulate the process of gene expression. TXTL systems have advanced to where the in vitro construction of viable, complex, self-assembling deoxyribonucleic acid-programmed biological entities is now possible. Previously, we demonstrated the cell-free synthesis of three bacteriophages from their genomes: MS2, ΦX174, T7. In this work, we present the complete synthesis of the phage T4 from its 169-kbp genome in one-pot TXTL reactions. This achievement, for one of the largest coliphages, demonstrates the integration of complex gene regulation, metabolism and self-assembly, and brings the bottom-up synthesis of biological systems to a new level.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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