Autoantigenicity of human C1q is associated with increased hydrophobicity due to conformational transitions in the globular heads

2015 ◽  
Vol 11 (5) ◽  
pp. 1370-1377 ◽  
Author(s):  
Vishnya Stoyanova ◽  
Vanya Bogoeva ◽  
Lidiya Petrova ◽  
Magdalena Tchorbadjieva ◽  
Svetla Petrova ◽  
...  
Keyword(s):  
Conformational Transitions ◽  
Structural Features ◽  
Model System

We analyzed the structural features of C1q that underlie its autoantigenicity by the means of a model system using an amphiphilic polyzwitterion (PZ).

scholarly journals Peptide-Induced Amyloid-Like Conformational Transitions in Proteins

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Vladimir Egorov ◽  
Natalia Grudinina ◽  
Andrey Vasin ◽  
Dmitry Lebedev
Keyword(s):  
Protein Conformation ◽  
Conformational Transitions ◽  
Structural Features ◽  
Open Reading Frames ◽  
Short Peptides ◽  
Disease Pathogenesis ◽  
Conformational Diseases ◽  
Physiological Processes ◽  
And Function ◽  
Reading Frames

Changes in protein conformation can occur both as part of normal protein functioning and during disease pathogenesis. The most common conformational diseases are amyloidoses. Sometimes the development of a number of diseases which are not traditionally related to amyloidoses is associated with amyloid-like conformational transitions of proteins. Also, amyloid-like aggregates take part in normal physiological processes such as memorization and cell signaling. Several primary structural features of a protein are involved in conformational transitions. Also the protein proteolytic fragments can cause the conformational transitions in the protein. Short peptides which could be produced during the protein life cycle or which are encoded by short open reading frames can affect the protein conformation and function.

scholarly journals Chemical Composition and Biological Activity of Paris quadrifolia L.

2012 ◽  
Vol 67 (11-12) ◽  
pp. 565-570 ◽  
Author(s):  
Kristina Jenett-Siems ◽  
Nadin Krause ◽  
Karsten Siems ◽  
Sven Jakupovic ◽  
Gerd Wallukat ◽  
...  
Keyword(s):  
Biological Activity ◽  
Chemical Composition ◽  
Structural Features ◽  
Model System ◽  
Cardiac Cells ◽  
Steroidal Saponin ◽  
Cellular Model ◽  
Potential Influence ◽  
Plant Compounds

A study of the components of Paris quadrifolia was undertaken to identify compounds with potential influence on cardiac cells, since previous reports suggested a cardiotoxic risk of this plant. Compounds isolated and identified included one new steroidal saponin, (23S,24S)- spirosta-5,25(27)-diene-1β,3β,21,23,24-pentol-1-O-β-D-apiofuranosyl-(1→3)-α-L-rhamnopyranosyl-( 1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranoside 21- O- β- D- apiofuranoside 24-O-β-D-fucopyranoside (1), demonstrating quite unusual structural features, as well as the known compounds 26-O-β-D-glucopyranosyl-(25R)-5-en-furost-3β,17α,22α,26-tetraol- 3- O- α- L- rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)-[α-L-rhamnopyranosyl - -(1→2)]- β- D- glucopyranoside (2), pennogenin 3-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamno pyranosyl- (1→4)-[α-L-rhamnopyranosyl-(1→ 2)]-β -D- glucopyranoside (3), 7- O- β- D-glucopyranosyl- kaempferol-3- O- β- D-glucopyranosyl-(1→2)-β- D-galactopyranoside (4), kaem pferol- 3-O-β-D-glucopyranosyl-(1→2)-β-D-galactopyranoside (5), 5-hydroxyecdysterone (6), and 20-hydroxyecdysone (7). The pennogenin derivative 3 showed strong cardiotoxic effects in an in vitro cellular model system, whereas the respective furostanol derivative 2 was inactive.

scholarly journals Phe-Gly motifs drive fibrillization of TDP-43’s prion-like domain droplets

2020 ◽  
Author(s):  
David Pantoja-Uceda ◽  
Cristiana Stuani ◽  
Douglas V. Laurents ◽  
Ann E. McDermott ◽  
Emanuele Buratti ◽  
...  
Keyword(s):  
Muscle Regeneration ◽  
Conformational Transitions ◽  
Structural Features ◽  
Droplet Surface ◽  
Pivotal Role ◽  
Visual Evidence ◽  
Droplet Form ◽  
Nmr Methods ◽  
Induced Aggregation

AbstractTDP-43 assembles various aggregate forms, including biomolecular condensates or functional and pathological amyloids, with roles in disparate scenarios (e.g. muscle regeneration versus neurodegeneration). The link between condensates and fibrils remains unclear, just as the factors controlling conformational transitions within these aggregate species: salt- or RNA-induced droplets may evolve into fibrils or remain in the droplet form, suggesting distinct endpoint species of different aggregation pathways. Using microscopy and NMR methods, we unexpectedly observed in vitro droplet formation in the absence of salts or RNAs, and provided visual evidence for fibrillization at the droplet surface/solvent interface but not the droplet interior. Our NMR analyses unambiguously uncovered a distinct amyloid conformation in which Phe-Gly motifs are key elements of the reconstituted fibril form, suggesting a pivotal role for these residues in creating the fibril core. This contrasts the minor participation of Phe-Gly motifs in initiation of the droplet form. Our results point to an intrinsic (i.e., non-induced) aggregation pathway that may exist over a broad range of conditions, and illustrate structural features that distinguishes between aggregate forms.

scholarly journals Structure-function properties in disordered condensates

2020 ◽  
Author(s):  
Kamal Bhandari ◽  
Michael A. Cotten ◽  
Jonggul Kim ◽  
Michael K. Rosen ◽  
Jeremy D. Schmit
Keyword(s):  
Binding Energy ◽  
Structure Function ◽  
Structural Features ◽  
Model System ◽  
Basic Unit ◽  
Filamentous Structure ◽  
3D Network ◽  
Total Composition ◽  
Liquid States

Biomolecular condensates appear throughout the cell serving a wide variety of functions. Many condensates appear to form by the assembly of multivalent molecules, which produce phase separated networks with liquid-like properties. These networks then recruit client molecules, with the total composition providing functionality. Here we use a model system of poly-SUMO and poly-SIM proteins to understand client-network interactions and find that the structure of the network plays a strong role in defining client recruitment, and thus functionality. The basic unit of assembly in this system is a zipper-like filament composed of alternating poly-SUMO and poly-SIM molecules. These filaments have defects of unsatisfied bonds that allow for both the formation of a 3D network and the recruitment of clients. The filamentous structure constrains the scaffold stoichiometries and the distribution of client recruitment sites that the network can accommodate. This results in a non-monotonic client binding response that can be tuned independently by the client valence and binding energy. These results show how the interactions within liquid states can be disordered yet still contain structural features that provide functionality to the condensate.

The Effect of Network Structure in the Equation of Rubber Elasticity

1976 ◽  
Vol 49 (5) ◽  
pp. 1232-1237 ◽  
Author(s):  
E. M. Valles ◽  
C. W. Macosko
Keyword(s):  
Shear Modulus ◽  
Temperature Dependence ◽  
Network Structure ◽  
Mechanical Response ◽  
Structural Features ◽  
Model System ◽  
Rubber Elasticity ◽  
Stress Strain ◽  
Good Agreement

Abstract Though the stress, strain, and temperature dependence for an ideal rubber is fairly well established, the relation between network structural features like crosslinks, dangling ends, and entanglements and mechanical response is uncertain. The modulus-structure relations recently derived by Miller and Macosko for several types of networks are tested here with a model system: the hydrosilation crosslinking of vinyl-terminated polydimethylsiloxane chains with a tetra-functional silane. Results of shear modulus as a function of extent of reaction and of stoichiometric imbalance are in good agreement with the theory.

scholarly journals Phe-Gly motifs drive fibrillization of TDP-43’s prion-like domain condensates

PLoS Biology ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. e3001198
Author(s):  
David Pantoja-Uceda ◽  
Cristiana Stuani ◽  
Douglas V. Laurents ◽  
Ann E. McDermott ◽  
Emanuele Buratti ◽  
...  
Keyword(s):  
Muscle Regeneration ◽  
Dna Binding Protein ◽  
Conformational Transitions ◽  
Structural Features ◽  
Droplet Surface ◽  
Visual Evidence ◽  
Droplet Form ◽  
Nmr Methods ◽  
Induced Aggregation

Transactive response DNA-binding Protein of 43 kDa (TDP-43) assembles various aggregate forms, including biomolecular condensates or functional and pathological amyloids, with roles in disparate scenarios (e.g., muscle regeneration versus neurodegeneration). The link between condensates and fibrils remains unclear, just as the factors controlling conformational transitions within these aggregate species: Salt- or RNA-induced droplets may evolve into fibrils or remain in the droplet form, suggesting distinct end point species of different aggregation pathways. Using microscopy and NMR methods, we unexpectedly observed in vitro droplet formation in the absence of salts or RNAs and provided visual evidence for fibrillization at the droplet surface/solvent interface but not the droplet interior. Our NMR analyses unambiguously uncovered a distinct amyloid conformation in which Phe-Gly motifs are key elements of the reconstituted fibril form, suggesting a pivotal role for these residues in creating the fibril core. This contrasts the minor participation of Phe-Gly motifs in initiation of the droplet form. Our results point to an intrinsic (i.e., non-induced) aggregation pathway that may exist over a broad range of conditions and illustrate structural features that distinguishes between aggregate forms.

scholarly journals Control of Capsid Transformations during Reovirus Entry

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 153
Author(s):  
Stephanie L. Gummersheimer ◽  
Anthony J. Snyder ◽  
Pranav Danthi
Keyword(s):  
Structural Changes ◽  
Current Knowledge ◽  
Conformational Transitions ◽  
Model System ◽  
Capsid Proteins ◽  
Knowledge Gaps ◽  
Outermost Layer ◽  
Mammalian Orthoreovirus ◽  
The Stability

Mammalian orthoreovirus (reovirus), a dsRNA virus with a multilayered capsid, serves as a model system for studying the entry of similar viruses. The outermost layer of this capsid undergoes processing to generate a metastable intermediate. The metastable particle undergoes further remodeling to generate an entry-capable form that delivers the genome-containing inner capsid, or core, into the cytoplasm. In this review, we highlight capsid proteins and the intricacies of their interactions that control the stability of the capsid and consequently impact capsid structural changes that are prerequisites for entry. We also discuss a novel proviral role of host membranes in promoting capsid conformational transitions. Current knowledge gaps in the field that are ripe for future investigation are also outlined.

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