scholarly journals (De)stabilization of Alpha-Synuclein Fibrillary Aggregation by Charged and Uncharged Surfactants

2021 ◽  
Vol 22 (22) ◽  
pp. 12509
Author(s):  
Joana Angélica Loureiro ◽  
Stéphanie Andrade ◽  
Lies Goderis ◽  
Ruben Gomez-Gutierrez ◽  
Claudio Soto ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Hydrophobic Interactions ◽  
Neurodegenerative Disorder ◽  
Sodium Dodecyl ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Cetyltrimethylammonium Chloride ◽  
Α Helix ◽  
Β Sheet

Parkinson’s disease (PD) is the second most common neurodegenerative disorder. An important hallmark of PD involves the pathological aggregation of proteins in structures known as Lewy bodies. The major component of these proteinaceous inclusions is alpha (α)-synuclein. In different conditions, α-synuclein can assume conformations rich in either α-helix or β-sheets. The mechanisms of α-synuclein misfolding, aggregation, and fibrillation remain unknown, but it is thought that β-sheet conformation of α-synuclein is responsible for its associated toxic mechanisms. To gain fundamental insights into the process of α-synuclein misfolding and aggregation, the secondary structure of this protein in the presence of charged and non-charged surfactant solutions was characterized. The selected surfactants were (anionic) sodium dodecyl sulphate (SDS), (cationic) cetyltrimethylammonium chloride (CTAC), and (uncharged) octyl β-D-glucopyranoside (OG). The effect of surfactants in α-synuclein misfolding was assessed by ultra-structural analyses, in vitro aggregation assays, and secondary structure analyses. The α-synuclein aggregation in the presence of negatively charged SDS suggests that SDS-monomer complexes stimulate the aggregation process. A reduction in the electrostatic repulsion between N- and C-terminal and in the hydrophobic interactions between the NAC (non-amyloid beta component) region and the C-terminal seems to be important to undergo aggregation. Fourier transform infrared spectroscopy (FTIR) measurements show that β-sheet structures comprise the assembly of the fibrils.

Are lysosomes potential therapeutic targets for Parkinson’s disease?

2021 ◽  
Vol 20 ◽  
Author(s):  
A. Petese ◽  
V. Cesaroni ◽  
S. Cerri ◽  
F. Blandini
Keyword(s):  
Neurodegenerative Disorder ◽  
Association Studies ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Genome Wide Association Studies ◽  
Lysosomal Dysfunction ◽  
Genome Wide ◽  
Nigrostriatal Neurons ◽  
Disease Modifying Treatment ◽  
Alpha Synuclein Aggregation

Background: Parkinson´s disease (PD) is the second most common neurodegenerative disorder, affecting 2-3% of the population over 65 years old. In addition to progressive degeneration of nigrostriatal neurons, the histopathological feature of PD is the accumulation of misfolded α-synuclein protein in abnormal cytoplasmatic inclusions, known as Lewy bodies (LBs). Recently, genome-wide association studies (GWAS) have indicated a clear association of variants within several lysosomal genes with risk for PD. Newly evolving data have been shedding light on the relationship between lysosomal dysfunction and alpha-synuclein aggregation. Defects in lysosomal enzymes could lead to the insufficient clearance of neurotoxic protein materials, possibly leading to selective degeneration of dopaminergic neurons. Specific modulation of lysosomal pathways and their components could be considered a novel opportunity for therapeutic intervention for PD. Aim: The purpose of this review is to illustrate lysosomal biology and describe the role of lysosomal dysfunction in PD pathogenesis. Finally, the most promising novel therapeutic approaches designed to modulate lysosomal activity, as a potential disease-modifying treatment for PD will be highlighted.

Use of synchrotron-based FTIR microspectroscopy to determine protein secondary structures of raw and heat-treated brown and golden flaxseeds: A novel approach

2005 ◽  
Vol 85 (4) ◽  
pp. 437-448 ◽  
Author(s):  
P. Yu ◽  
J. J. McKinnon ◽  
H. W. Soita ◽  
C. R. Christensen ◽  
D. A. Christensen
Keyword(s):  
Secondary Structure ◽  
Matrix Protein ◽  
Protein Secondary Structure ◽  
Secondary Structures ◽  
Heat Processing ◽  
Lower Percentage ◽  
Protein Secondary Structures ◽  
Novel Approach ◽  
Α Helix ◽  
Β Sheet

The objectives of the study were to use synchrotron Fourier transform infrared microspectroscopy (S-FTIR) as a novel approach to: (1) reveal ultra-structural chemical features of protein secondary structures of flaxseed tissues affected by variety (golden and brown) and heat processing (raw and roasted), and (2) quantify protein secondary structures using Gaussian and Lorentzian methods of multi-component peak modeling. By using multi-component peak modeling at protein amide I region of 1700–1620 cm-1, the results showed that the golden flaxseed contained relatively higher percentage of α-helix (47.1 vs. 36.9%), lower percentage of β-sheet (37.2 vs. 46.3%) and higher (P < 0.05) ratio of α-helix to β-sheet than the brown flaxseed (1.3 vs. 0.8). The roasting reduced (P < 0.05) percentage of α-helix (from 47.1 to 36.1%), increased percentage of β-sheet (from 37.2 to 49.8%) and reduced α-helix to β-sheet ratio (1.3 to 0.7) of the golden flaxseed tissues. However, the roasting did not affect percentage and ratio of α-helix and β-sheet in the brown flaxseed tissue. No significant differences were found in quantification of protein secondary structures between Gaussian and Lorentzian methods. These results demonstrate the potential of highly spatially resolved S-FTIR to localize relatively pure protein in the tissue and reveal protein secondary structures at a cellular level. The results indicated relative differences in protein secondary structures between flaxseed varieties and differences in sensitivities of protein secondary structure to the heat processing. Further study is needed to understand the relationship between protein secondary structure and protein digestion and utilization of flaxseed and to investigate whether the changes in the relative amounts of protein secondary structures are primarily responsible for differences in protein availability. Key words: Synchrotron, FTIR microspectrosopy, flaxseeds, intrinsic structural matrix, protein secondary structures, protein nutritive value

scholarly journals TraA and its N-terminal relaxase domain of the Gram-positive plasmid pIP501 show specific oriT binding and behave as dimers in solution

2005 ◽  
Vol 387 (2) ◽  
pp. 401-409 ◽  
Author(s):  
Jolanta KOPEC ◽  
Alexander BERGMANN ◽  
Gerhard FRITZ ◽  
Elisabeth GROHMANN ◽  
Walter KELLER
Keyword(s):  
Amino Acids ◽  
Broad Host Range ◽  
Mobility Shift ◽  
Gram Positive ◽  
Nick Site ◽  
Α Helix ◽  
Electrophoretic Mobility Shift Assays ◽  
Dna Complex ◽  
Β Sheet

TraA is the DNA relaxase encoded by the broad-host-range Grampositive plasmid pIP501. It is the second relaxase to be characterized from plasmids originating from Gram-positive organisms. Full-length TraA (654 amino acids) and the N-terminal domain (246 amino acids), termed TraAN246, were expressed as 6×His-tagged fusions and purified. Small-angle X-ray scattering and chemical cross-linking proved that TraAN246 and TraA form dimers in solution. Both proteins revealed oriTpIP501 (origin of transfer of pIP501) cleavage activity on supercoiled plasmid DNA in vitro. oriT binding was demonstrated by electrophoretic mobility shift assays. Radiolabelled oligonucleotides covering different parts of oriTpIP501 were subjected to binding with TraA and TraAN246. The KD of the protein–DNA complex encompassing the inverted repeat, the nick site and an additional 7 bases was found to be 55 nM for TraA and 26 nM for TraAN246. The unfolding of both protein constructs was monitored by measuring the change in the CD signal at 220 nm upon temperature change. The unfolding transition of both proteins occurred at approx. 42 °C. CD spectra measured at 20 °C showed 30% α-helix and 13% β-sheet for TraA, and 27% α-helix and 18% β-sheet content for the truncated protein. Upon DNA binding, an enhanced secondary structure content and increased thermal stability were observed for the TraAN246 protein, suggesting an induced-fit mechanism for the formation of the specific relaxase–oriT complex.

scholarly journals Alpha-synuclein from patient Lewy bodies exhibits distinct pathological activity that can be propagated in vitro

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Nicholas P. Marotta ◽  
Jahan Ara ◽  
Norihito Uemura ◽  
Marshall G. Lougee ◽  
Emily S. Meymand ◽  
...  
Keyword(s):  
Cellular Response ◽  
Amyloid Fibrils ◽  
Cultured Cells ◽  
Biological Activities ◽  
Lewy Bodies ◽  
Alpha Synuclein ◽  
Biological Behavior ◽  
Motor Deficits ◽  
Original Material

AbstractLewy bodies (LBs) are complex, intracellular inclusions that are common pathological features of many neurodegenerative diseases. They consist largely of aggregated forms of the protein alpha-Synuclein (α-Syn), which misfolds to give rise to beta-sheet rich amyloid fibrils. The aggregation of monomers into fibrils occurs readily in vitro and pre-formed fibrils (PFFs) generated from recombinant α-Syn monomers are the basis of many models of LB diseases. These α-Syn PFFs recapitulate many pathological phenotypes in both cultured cells and animal models including the formation of α-Syn rich, insoluble aggregates, neuron loss, and motor deficits. However, it is not clear how closely α-Syn PFFs recapitulate the biological behavior of LB aggregates isolated directly from patients. Direct interrogation of the cellular response to LB-derived α-Syn has thus far been limited. Here we demonstrate that α-Syn aggregates derived from LB disease patients induce pathology characterized by a prevalence of large somatic inclusions that is distinct from the primarily neuritic pathology induced by α-Syn PFFs in our cultured neuron model. Moreover, these LB-derived aggregates can be amplified in vitro using recombinant α-Syn to generate aggregates that maintain the unique, somatic pathological phenotype of the original material. Amplified LB aggregates also showed greater uptake in cultured neurons and greater pathological burden and more rapid pathological spread in injected mouse brains, compared to α-Syn PFFs. Our work indicates that LB-derived α-Syn from diseased brains represents a distinct conformation species with unique biological activities that has not been previously observed in fully recombinant α-Syn aggregates and demonstrate a new strategy for improving upon α-Syn PFF models of synucleinopathies using amplified LBs.

scholarly journals Parkinson’s disease is a type of amyloidosis featuring accumulation of amyloid fibrils of α-synuclein

2019 ◽  
Vol 116 (36) ◽  
pp. 17963-17969 ◽  
Author(s):  
Katsuya Araki ◽  
Naoto Yagi ◽  
Koki Aoyama ◽  
Chi-Jing Choong ◽  
Hideki Hayakawa ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Amyloid Fibrils ◽  
Lewy Bodies ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Β Sheet ◽  
The Brain

Many neurodegenerative diseases are characterized by the accumulation of abnormal protein aggregates in the brain. In Parkinson’s disease (PD), α-synuclein (α-syn) forms such aggregates called Lewy bodies (LBs). Recently, it has been reported that aggregates of α-syn with a cross-β structure are capable of propagating within the brain in a prionlike manner. However, the presence of cross-β sheet-rich aggregates in LBs has not been experimentally demonstrated so far. Here, we examined LBs in thin sections of autopsy brains of patients with PD using microbeam X-ray diffraction (XRD) and found that some of them gave a diffraction pattern typical of a cross-β structure. This result confirms that LBs in the brain of PD patients contain amyloid fibrils with a cross-β structure and supports the validity of in vitro propagation experiments using artificially formed amyloid fibrils of α-syn. Notably, our finding supports the concept that PD is a type of amyloidosis, a disease featuring the accumulation of amyloid fibrils of α-syn.

scholarly journals Prion Interaction with Normal Protein in Topological Changing Secondary Structure to Aggregation

2020 ◽  
Vol 9 (2) ◽  
pp. 53
Author(s):  
Yao Yao
Keyword(s):  
Hydrogen Bond ◽  
Secondary Structure ◽  
Amyloid Fibril ◽  
Double Helix ◽  
Β Amyloid ◽  
Structural Analogy ◽  
Β Sheets ◽  
Α Helix ◽  
Dna Double Helix ◽  
Β Sheet

<p>Prion is a protein smaller than virus and it infects host in the absence of nucleic acid. The secondary structure of protein folds incorrectly from α-helices to β-sheets through breaking and re-formation of hydrogen bond. Structural analogy of α-helix and DNA double helix and comparing differences between α-helix and β-sheet show prion's infectivity and propagation. Aggregates of dimers and polymers generate β-amyloid fibril in Alzheimer's disease.</p>

scholarly journals Simultaneous Occurrence of Bioactive Compounds (Melatonin, Protocatechuic Acid and Hydroxytyrosol) Increases Their Neuroprotective Effects Against Alpha-Synuclein-Induced Proteotoxicity

2018 ◽  
Author(s):  
Marta Gallardo-Fernández ◽  
Ruth Hornedo-Ortega ◽  
Ana B Cerezo ◽  
Ana M Troncoso ◽  
Mª Carmen Garcia-Parrilla
Keyword(s):  
Bioactive Compounds ◽  
Protocatechuic Acid ◽  
Lewy Bodies ◽  
Initial Step ◽  
Inhibitory Effect ◽  
Alpha Synuclein ◽  
Simultaneous Occurrence ◽  
Neuroprotective Effects ◽  
In Vitro Techniques

The abnormal assembly of &alpha;-synuclein (&alpha;-Syn) is an initial step in the formation of Lewy bodies in the brain, which finally causes the neuronal death, being considered as a pathological hallmark in Parkinson&rsquo;s disease (PD). Certain food bioactives or their metabolites at very low concentrations can trespass the blood brain barrier (BBB) that might, thereafter, act simultaneously. The aim of this work was to evaluate the inhibitory and destabilising capacities on &alpha;-Syn kinetics and the neuroprotective effects of three well-known bioactive compounds able to cross the BBB and present in foods; melatonin (MEL), protocatechuic acid (PCA) and hydroxytyrosol (HT), and their combinations. For this purpose, different in vitro techniques (Thioflavin T (ThT), Transmission Electronic Microscopy (TEM), electrophoresis and MTT assay) were used. All tested compounds and their combinations were able to abolish the toxicity induced by &alpha;-Syn. In addition, the combination of PCA (100 &micro;M) +HT (100 &micro;M) showed the highest inhibitory effect against &alpha;-Syn fibril formation and destabilises &alpha;-Syn fibrils (88 and 62%, respectively). This is the first time that MEL, PCA and HT prove a joint effect against &alpha;-Syn aggregation and toxicity when they are tested together.

scholarly journals Effect of pH on the Conformational Transition of Silk Fibroin in Aqueous Solution Monitored by Thioflavin-T Fluorescence

2021 ◽  
Author(s):  
Ben Jia ◽  
Lan Jia ◽  
Jingxin Zhu
Keyword(s):  
Aqueous Solution ◽  
Secondary Structure ◽  
Silk Fibroin ◽  
Conformational Transition ◽  
Thioflavin T ◽  
Random Coil ◽  
Fluorescence Dye ◽  
Assembly Behavior ◽  
Β Sheet

Abstract In this work, the potential application of the fluorescence dye Thioflavin-T (ThT), which can specifically bind to amyloid, as a powerful tool for monitoring secondary structure transitions of silk fibroin (SF) induced by pH was examined. Results showed that ThT emission intensities substantially increased when pH decreased from 6.8 to 4.8. This increase may be due to conformational transitions from random coil to β-sheet. The morphology and secondary structure of SF were also investigated via TEM, AFM and circular dichroism spectroscopy. The information obtained herein can be utilized not only for the development of convenient and efficient noninvasive method for monitoring the assembly behavior of SF in aqueous solution but also for in vitro fluorescence imaging.

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