Residue-specific identification of phase separation hot spots of Alzheimer's-related protein tau

Ambadipudi, Susmitha; Reddy, Jithender G.; Biernat, Jacek; Mandelkow, Eckhard; Zweckstetter, Markus

doi:10.1039/c9sc00531e

Cited by 79 publications

(89 citation statements)

References 36 publications

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“…Even though the LLPS-promoting effect of zinc is critically dependent on the presence of at least one Cys residue within the pseudo-repeat region, the latter region alone appears to be insufficient to support this effect, as the K18 fragment was not able to undergo LLPS, even at high zinc concentrations. It should be noted that droplet formation by K18 (in the absence of zinc) was previously reported (28,29). However, this was observed only upon many hours of incubation at high protein concentration (~100 µM) in a pH 8.8 buffer, i.e., near the isolelectric point of the K18 fragment.…”

Section: Resultsmentioning

confidence: 67%

Zinc promotes liquid–liquid phase separation of tau protein

Singh

Boyko

et al. 2020

Journal of Biological Chemistry

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Tau is a microtubule-associated protein that plays a major role in Alzheimer's disease (AD) and other tauopathies. Recent reports indicate that, in the presence of crowding agents, tau can undergo liquid-liquid phase separation (LLPS), forming highly dynamic liquid droplets. Here, using recombinantly expressed proteins, turbidimetry, fluorescence microscopy imaging, and fluorescence recovery after photobleaching (FRAP) assays, we show that the divalent transition metal zinc strongly promotes this process, shifting the equilibrium phase boundary to lower protein or crowding agent concentrations. We observed no tau LLPS-promoting effect for any other divalent transition metal ions tested, including Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , and Cu 2+ . We also demonstrate that multiple zinc-binding sites on tau are involved in the LLPS-promoting effect and provide insights into the mechanism of this process. Zinc concentration is highly elevated in AD brains, and this metal ion is believed to be an important player in the pathogenesis of this disease. Thus, the present findings bring a new dimension to understanding the relationship between zinc homeostasis and the pathogenic process in AD and related neurodegenerative disorders. ____________________________________ https://www.jbc.org/cgi/

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Section: Resultsmentioning

confidence: 67%

Zinc promotes liquid–liquid phase separation of tau protein

Singh

Boyko

et al. 2020

Journal of Biological Chemistry

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“…In samples near the saturation concentration where a small fraction of the protein undergoes LLPS, other studies have probed the onset of LLPS by measuring the signal intensities in standard one-and twodimensional spectra of the protein remaining in the dispersed phase (17,18). The fraction of protein in the condensed phase contributes very little to the total signal due to enhanced relax-ation rates in the condensed phase, leading to extreme signal broadening and leaving only the signals from the dispersed phase (9,(17)(18)(19)(20)(21)(22). Whereas dispersed phase samples are useful in characterizing certain aspects of protein systems that undergo LLPS, they are limited as conclusions about the condensed phase are indirect.…”

Section: Dispersed Phasementioning

confidence: 99%

“…Changes in the position or intensity of the resonances corresponding to each residue have been used to map self-interactions and interactions with protein-binding partners and ligands of LLPS systems (9,17,18,20,24,27,37,38). The proteasomal shuttle protein, ubiquilin (UBQLN), phase-separates and localizes to stress granules (37).…”

Section: Chemical Shiftsmentioning

confidence: 99%

“…For example, Burke et al (24) mapped the nonspecific interactions between the low-complexity domain of FUS and RNA polymerase II C-terminal heptad tail in the dispersed phase. Finally, interactions between LLPS-prone proteins and small molecules can be monitored using chemical shifts (20,39). For example, the interaction of the low-complexity domain of FUS and potential therapeutic small molecules was quantified-the chemotherapeutic mitoxantrone was found to interact with tyrosine residues present in the low-complexity domain of FUS in the dispersed phase (39).…”

Section: Chemical Shiftsmentioning

confidence: 99%

“…Because the condensed phase of many protein systems is highly viscous, the intrinsic line widths that result are broadened due to the decreased molecular motions in the condensed phase (10,20,24,25). To retain residue-by-residue resolution obtained in the dispersed state, one may change the apodization function used to process the data to increase resolution.…”

Section: Chemical Shiftsmentioning

confidence: 99%

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The (un)structural biology of biomolecular liquid-liquid phase separation using NMR spectroscopy

Murthy

Fawzi

2020

Journal of Biological Chemistry

107

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Liquid-liquid phase separation (LLPS) of proteins and nucleic acids is a phenomenon that underlies membraneless compartmentalization of the cell. The underlying molecular interactions that underpin biomolecular LLPS have been of increased interest due to the importance of membraneless organelles in facilitating various biological processes and the disease association of several of the proteins that mediate LLPS. Proteins that are able to undergo LLPS often contain intrinsically disordered regions and remain dynamic in solution. Solution-state NMR spectroscopy has emerged as a leading structural technique to characterize protein LLPS due to the variety and specificity of information that can be obtained about intrinsically disordered sequences. This review discusses practical aspects of studying LLPS by NMR, summarizes recent work on the molecular aspects of LLPS of various protein systems, and discusses future opportunities for characterizing the molecular details of LLPS to modulate phase separation.

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Tau liquid–liquid phase separation: At the crossroads of tau physiology and tauopathy

Islam

Shen

Regmi

et al. 2022

Journal Cellular Physiology

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Abnormal deposition of tau in neurons is a hallmark of Alzheimer's disease and several other neurodegenerative disorders. In the past decades, extensive efforts have been made to explore the mechanistic pathways underlying the development of tauopathies. Recently, the discovery of tau droplet formation by liquid–liquid phase separation (LLPS) has received a great deal of attention. It has been reported that tau condensates have a biological role in promoting and stabilizing microtubule (MT) assembly. Furthermore, it has been hypothesized that the transition of phase‐separated tau droplets to a gel‐like state and then to fibrils is associated with the pathology of neurodegenerative diseases. In this review, we outline LLPS, the structural disorder that facilitates tau droplet formation, the effects of posttranslational modification of tau on condensate formation, the physiological function of tau droplets, the pathways from droplet to toxic fibrils, and the therapeutic strategies for tauopathies that might evolve from toxic droplets. We expect a deeper understanding of tau LLPS will provide additional insights into tau physiology and tauopathies.

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Residue-specific identification of phase separation hot spots of Alzheimer's-related protein tau

Abstract: Visualizing liquid–liquid phase separation by NMR spectroscopy: LLPS of the Alzheimer's-related protein tau involves aggregation-prone hexapeptides and activity regulating KXGS motifs.

Cited by 79 publications

References 36 publications

Zinc promotes liquid–liquid phase separation of tau protein

Zinc promotes liquid–liquid phase separation of tau protein

The (un)structural biology of biomolecular liquid-liquid phase separation using NMR spectroscopy

Tau liquid–liquid phase separation: At the crossroads of tau physiology and tauopathy

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