Semisynthetic and Enzyme‐Mediated Conjugate Preparations Illuminate the Ubiquitination‐Dependent Aggregation of Tau Protein

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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“…Also, ubiquitination in these two positions was found earlier to disfavor heparin-induced fibril formation (Munari et al, 2020).…”

Section: Other Mutationsmentioning

confidence: 95%

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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“…32 One such method is isolating Tau from post-mortem samples or from tauopathy mouse models. Another common method involves enzymatic functionalization of Tau to obtain phosphorylated, acetylated, 33 and glycosylated forms, but this method lacks specificity and control over the location or extent of modifications. Furthermore, preparation of pure Tau is challenging because, as a disordered protein, Tau is vulnerable to protease degradation.…”

Section: ■ Introductionmentioning

confidence: 99%

Chemical Synthesis of Microtubule-Associated Protein Tau

Powell,

Jing,

Walczak

2023

J. Am. Chem. Soc.

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Deposits of the microtubule-associated protein Tau (MAPT) serve as a hallmark of neurodegenerative diseases known as tauopathies. Numerous studies have demonstrated that in diseases such as Alzheimer's disease (AD), Tau undergoes extensive remodeling. The attachment of post-translational modifications distributed throughout the entire sequence of the protein correlates with clinical presentation. A systematic examination of these protein alterations can shed light on their roles in both healthy and diseased states. However, the ability to access these modifications in the entire protein chain is limited as Tau can only be produced recombinantly or through semisynthesis. In this article, we describe the first chemical synthesis of the longest 2N4R isoform of Tau, consisting of 441 amino acids. The 2N4R Tau was divided into 3 major segments and a total of 11 fragments, all of which were prepared via solid-phase peptide synthesis. The successful chemical strategy has relied on the strategic use of two cysteine sites (C291 and C322) for the native chemical ligations (NCLs). This was combined with modern preparative protein chemistries, such as mercaptothreonine ligation (T205), diselenide−selenoester ligation (D358), and mutations of mercaptoamino acids into native residues via homogeneous radical desulfurization (A40, A77, A119, A157, A246, and A390). The successful completion of the synthesis has established a robust and scalable route to the native protein in multimilligram quantities and high purity. In broader terms, the presented strategy can be applied to the preparation of other shorter isoforms of Tau as well as to introduce all post-translational modifications that are characteristic of tauopathies such as AD.

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“…32 One such method is isolating Tau from post-mortem samples or from tauopathy mouse models. Another common method involves enzymatic functionalization of Tau to obtain phosphorylated, acetylated, 33 ubiquitinated, 34 and glycosylated forms, but this method lacks specificity and control over the location or extent of modifications. Furthermore, preparation of pure Tau is challenging because, as a disordered protein, Tau is vulnerable to protease degradation.…”

Section: Introductionmentioning

confidence: 99%

Chemical Synthesis of Microtubule-Associated Protein Tau 2N4R

Powell

Jing

Walczak

2023

Preprint

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Deposits of the microtubule-associated protein tau (MAPT) serve as a hallmark of neurodegenerative diseases known as tauopathies. Numerous studies have demonstrated that in diseases such as Alzheimer’s disease (AD), tau undergoes extensive remodeling. The attachment of post-translational modifications distributed throughout the entire sequence of the protein cor-relates with the clinical presentation. A systematic examination of these protein alterations can shed light on their roles in both healthy and diseased states. However, the ability to access these modifications in the entire protein chain is limited as tau can only be produced recombinantly or through semi-synthesis. In this paper, we describe the first chemical synthesis of the longest 2N4R isoform of tau, consisting of 441 amino acids. The 2N4R tau was divided into three major segments and a total of eleven fragments, all of which were prepared via solid-phase peptide synthesis. The successful chemical strategy re-lied on the strategic use of two cysteine sites (C291 and C322) for native chemical ligations (NCL). This was combined with modern preparative protein chemistries, such as threonine ligation (T205), diselenide-selenoester ligation (D358), and mutations of mercaptoamino acids into native residues via homogeneous radical desulfurization (A40, A77, A119, A157, A246, A390). The successful completion of the synthesis established a robust and scalable route to the native protein in multimilligram quantities and high purity. In broader terms, the presented strategy can be applied to the preparation of other shorter isoforms of tau, as well as to introduce all post-translational modifications that are characteristic of tauopathies such as AD, progressive supranuclear palsy, and frontotemporal dementia.

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Semisynthetic and Enzyme‐Mediated Conjugate Preparations Illuminate the Ubiquitination‐Dependent Aggregation of Tau Protein

Cited by 5 publications

References 36 publications

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

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

Chemical Synthesis of Microtubule-Associated Protein Tau

Chemical Synthesis of Microtubule-Associated Protein Tau 2N4R

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