Lipid membrane templated misfolding and self-assembly of intrinsically disordered tau protein

AbstractThe aggregation of the intrinsically disordered tau protein into highly ordered β-sheet fibrils is implicated in many neurodegenerative disorders. Fibrillation mechanism remains unresolved, particularly early events that trigger tau misfolding and assembly. We investigated the role membrane plays in modulating aggregation of three tau variants, the largest isoform hTau40, the truncated construct K18, and a hyperphosphorylation mutant hTau40/3Epi. Despite being charged and soluble, tau proteins were also highly surface active and favorably interacted with anionic, but not zwitterionic, lipid monolayer at the air/water interface. Membrane binding induced macroscopic tau phase separation and β-sheet-rich tau oligomer formation. Concomitantly, membrane morphology and lipid packing became disrupted. Our findings support a general tau aggregation mechanism wherein tau’s inherent surface activity and favorable electrostatic interactions drive tau-membrane association, inducing tau phase separation that is accompanied by misfolding and self-assembly of disordered tau into β-sheet-rich oligomers, which subsequently seed fibrillation and deposition into diseased tissues.

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Lipid membrane templated misfolding and self-assembly of intrinsically disordered tau protein

Scientific Reports ◽

10.1038/s41598-020-70208-6 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

Jaroslaw Majewski ◽

Emmalee M. Jones ◽

Crystal M. Vander Zanden ◽

Jacek Biernat ◽

Eckhard Mandelkow ◽

...

Keyword(s):

Tau Protein ◽

Self Assembly ◽

Lipid Membrane ◽

Intrinsically Disordered

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Lipid Membrane Templated Misfolding and Self-Assembly of Intrinsically Disordered Tau Protein

Biophysical Journal ◽

10.1016/j.bpj.2017.11.3768 ◽

2018 ◽

Vol 114 (3) ◽

pp. 616a

Author(s):

Jaroslaw P. Majewski ◽

Emmalee M. Jones ◽

Jacek Biernat ◽

Eckhard Mandelkow ◽

Eva Y. Chi

Keyword(s):

Tau Protein ◽

Self Assembly ◽

Lipid Membrane ◽

Intrinsically Disordered

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Basic Residue Clusters in Intrinsically Disordered Regions of Peripheral Membrane Proteins: Modulating 2D Diffusion on Cell Membranes

Physchem ◽

10.3390/physchem1020010 ◽

2021 ◽

Vol 1 (2) ◽

pp. 152-162

Author(s):

Miquel Pons

Keyword(s):

Membrane Proteins ◽

Electrostatic Interactions ◽

Lipid Membrane ◽

Conformational Ensemble ◽

Basic Residue ◽

Intrinsically Disordered ◽

Intrinsically Disordered Regions ◽

Peripheral Membrane Proteins ◽

Charged Residues ◽

Disordered Regions

A large number of peripheral membrane proteins transiently interact with lipids through a combination of weak interactions. Among them, electrostatic interactions of clusters of positively charged amino acid residues with negatively charged lipids play an important role. Clusters of charged residues are often found in intrinsically disordered protein regions, which are highly abundant in the vicinity of the membrane forming what has been called the disordered boundary of the cell. Beyond contributing to the stability of the lipid-bound state, the pattern of charged residues may encode specific interactions or properties that form the basis of cell signaling. The element of this code may include, among others, the recognition, clustering, and selective release of phosphatidyl inositides, lipid-mediated protein-protein interactions changing the residence time of the peripheral membrane proteins or driving their approximation to integral membrane proteins. Boundary effects include reduction of dimensionality, protein reorientation, biassing of the conformational ensemble of disordered regions or enhanced 2D diffusion in the peri-membrane region enabled by the fuzzy character of the electrostatic interactions with an extended lipid membrane.

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Liquid–liquid phase separation of tau protein: The crucial role of electrostatic interactions

Journal of Biological Chemistry ◽

10.1074/jbc.ac119.009198 ◽

2019 ◽

Vol 294 (29) ◽

pp. 11054-11059 ◽

Cited By ~ 35

Author(s):

Solomiia Boyko ◽

Xu Qi ◽

Tien-Hao Chen ◽

Krystyna Surewicz ◽

Witold K. Surewicz

Keyword(s):

Phase Separation ◽

Liquid Phase ◽

Tau Protein ◽

Crucial Role ◽

Electrostatic Interactions ◽

Liquid Phase Separation ◽

Liquid Liquid Phase Separation

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Identifying sequence perturbations to an intrinsically disordered protein that determine its phase-separation behavior

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2000223117 ◽

2020 ◽

Vol 117 (21) ◽

pp. 11421-11431 ◽

Cited By ~ 21

Author(s):

Benjamin S. Schuster ◽

Gregory L. Dignon ◽

Wai Shing Tang ◽

Fleurie M. Kelley ◽

Aishwarya Kanchi Ranganath ◽

...

Keyword(s):

Phase Separation ◽

Intrinsically Disordered Proteins ◽

Lipid Membrane ◽

Coarse Grained ◽

Disordered Proteins ◽

Sequence Features ◽

Intrinsically Disordered ◽

Arginine Residues

Phase separation of intrinsically disordered proteins (IDPs) commonly underlies the formation of membraneless organelles, which compartmentalize molecules intracellularly in the absence of a lipid membrane. Identifying the protein sequence features responsible for IDP phase separation is critical for understanding physiological roles and pathological consequences of biomolecular condensation, as well as for harnessing phase separation for applications in bioinspired materials design. To expand our knowledge of sequence determinants of IDP phase separation, we characterized variants of the intrinsically disordered RGG domain from LAF-1, a model protein involved in phase separation and a key component of P granules. Based on a predictive coarse-grained IDP model, we identified a region of the RGG domain that has high contact probability and is highly conserved between species; deletion of this region significantly disrupts phase separation in vitro and in vivo. We determined the effects of charge patterning on phase behavior through sequence shuffling. We designed sequences with significantly increased phase separation propensity by shuffling the wild-type sequence, which contains well-mixed charged residues, to increase charge segregation. This result indicates the natural sequence is under negative selection to moderate this mode of interaction. We measured the contributions of tyrosine and arginine residues to phase separation experimentally through mutagenesis studies and computationally through direct interrogation of different modes of interaction using all-atom simulations. Finally, we show that despite these sequence perturbations, the RGG-derived condensates remain liquid-like. Together, these studies advance our fundamental understanding of key biophysical principles and sequence features important to phase separation.

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Phase separation of both a plant virus movement protein and cellular factors support virus-host interactions

10.1101/2021.05.11.443547 ◽

2021 ◽

Author(s):

Shelby L Brown ◽

Jared P. May

Keyword(s):

Phase Separation ◽

Mosaic Virus ◽

Self Assembly ◽

Electrostatic Interactions ◽

Movement Protein ◽

Virus Movement ◽

In Planta ◽

Ribonucleoprotein Complexes

Phase separation concentrates biomolecules, which should benefit RNA viruses that must sequester viral and host factors during an infection. Here, the p26 movement protein from Pea enation mosaic virus 2 (PEMV2) was found to phase separate and partition in nucleoli and G3BP stress granules (SGs) in vivo . Electrostatic interactions drive p26 phase separation as mutation of basic (R/K-G) or acidic (D/E-G) residues either blocked or reduced phase separation, respectively. During infection, p26 must partition inside the nucleolus and interact with fibrillarin (Fib2) as a pre-requisite for systemic trafficking of viral RNAs. Partitioning of p26 in pre-formed Fib2 droplets was dependent on p26 phase separation suggesting that phase separation of viral movement proteins supports nucleolar partitioning and virus movement. Furthermore, viral ribonucleoprotein complexes containing p26, Fib2, and PEMV2 RNA were formed via phase separation in vitro and could provide the basis for self-assembly in planta . Interestingly, both R/K-G and D/E-G p26 mutants failed to support systemic trafficking of a Tobacco mosaic virus (TMV) vector in Nicotiana benthamiana suggesting that p26 phase separation, proper nucleolar partitioning, and systemic movement are intertwined. p26 also partitioned in SGs and G3BP over-expression restricted PEMV2 accumulation >20-fold. Expression of phase separation-deficient G3BP only restricted PEMV2 5-fold, demonstrating that G3BP phase separation is critical for maximum antiviral activity.

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Quadruplex Folding of DNA Promotes the Condensation of Linker Histones via Liquid-Liquid Phase Separation

10.26434/chemrxiv.11822076.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Masahiro Mimura ◽

Shunsuke Tomita ◽

Yoichi Shinkai ◽

Kentaro Shiraki ◽

Ryoji Kurita

Keyword(s):

Phase Separation ◽

Liquid Phase ◽

Electrostatic Interactions ◽

Droplet Formation ◽

Liquid Phase Separation ◽

Intrinsically Disordered ◽

G Quadruplex ◽

Dna Quadruplex ◽

Liquid Liquid Phase Separation

<p>Liquid-liquid phase separation (LLPS) of proteins and DNA has recently emerged as a possible mechanism underlying the dynamic organization of chromatin. We herein report the role of DNA quadruplex folding in liquid droplet formation via LLPS induced by interactions between DNA and linker histone H1 (H1), a key regulator of chromatin organization. Fluidity measurements inside the droplets and binding assays using G-quadruplex-selective probes demonstrated that quadruplex DNA structures, such as the G-quadruplex and i-motif, promote droplet formation with H1 and decrease molecular motility within droplets. The dissolution of the droplets in the presence of additives indicated that in addition to electrostatic interactions between the DNA and the intrinsically disordered region of H1, π-π stacking between quadruplex DNAs could potentially drive droplet formation. Given that DNA quadruplex structures are well documented in heterochromatin regions, it is imperative to understand the role of DNA quadruplex folding in the context of intranuclear LLPS.<b></b></p>

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The Liquid Structure of Elastin

10.1101/095927 ◽

2016 ◽

Cited By ~ 1

Author(s):

Sarah Rauscher ◽

Régis Pomès

Keyword(s):

Phase Separation ◽

Self Assembly ◽

Hydrophobic Effect ◽

Liquid Structure ◽

Extensive Study ◽

Disordered Proteins ◽

Elastic Recoil ◽

Intrinsically Disordered ◽

Polypeptide Backbone ◽

Dynamics Simulations

ABSTRACTThe protein elastin imparts extensibility, elastic recoil, and resilience to tissues including arterial walls, skin, lung alveoli, and the uterus. Elastin and elastin-like peptides are intrinsically disordered hydrophobic proteins that undergo liquid-liquid phase separation upon self-assembly. Despite extensive study for over eighty years, the structure of elastin remains controversial. We use molecular dynamics simulations on a massive scale to elucidate the structural ensemble of aggregated elastin-like peptides. Consistent with the entropic nature of elastic recoil, the aggregated state is stabilized both by the hydrophobic effect and by conformational entropy. The polypeptide backbone forms transient, sparse hydrogen-bonded turns and remains significantly hydrated even as self-assembly triples the extent of nonpolar side-chain contacts. The assembly approaches a maximally-disordered, melt-like state, which may be called the liquid state of proteins. These findings resolve long-standing controversies regarding elastin structure and function and afford insight of broad relevance to the phase separation of disordered proteins.

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Coupling Bulk Phase Separation of Disordered Proteins to Membrane Domain Formation in Molecular Simulations on a Bespoke Compute Fabric

Membranes ◽

10.3390/membranes12010017 ◽

2021 ◽

Vol 12 (1) ◽

pp. 17

Author(s):

Julian C. Shillcock ◽

David B. Thomas ◽

Jonathan R. Beaumont ◽

Graeme M. Bragg ◽

Mark L. Vousden ◽

...

Keyword(s):

Phase Separation ◽

Intrinsically Disordered Proteins ◽

Lipid Membrane ◽

Molecular Simulations ◽

Coarse Grained ◽

Disordered Proteins ◽

Computational Techniques ◽

Domain Formation ◽

Intrinsically Disordered ◽

Ideal Mixing

Phospholipid membranes surround the cell and its internal organelles, and their multicomponent nature allows the formation of domains that are important in cellular signalling, the immune system, and bacterial infection. Cytoplasmic compartments are also created by the phase separation of intrinsically disordered proteins into biomolecular condensates. The ubiquity of lipid membranes and protein condensates raises the question of how three-dimensional droplets might interact with two-dimensional domains, and whether this coupling has physiological or pathological importance. Here, we explore the equilibrium morphologies of a dilute phase of a model disordered protein interacting with an ideal-mixing, two-component lipid membrane using coarse-grained molecular simulations. We find that the proteins can wet the membrane with and without domain formation, and form phase separated droplets bound to membrane domains. Results from much larger simulations performed on a novel non-von-Neumann compute architecture called POETS, which greatly accelerates their execution compared to conventional hardware, confirm the observations. Reducing the wall clock time for such simulations requires new architectures and computational techniques. We demonstrate here an inter-disciplinary approach that uses real-world biophysical questions to drive the development of new computing hardware and simulation algorithms.

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