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Tchounwou C, Jobanputra AJ, Lasher D, Fletcher BJ, Jacinto J, Bhaduri A, Best RL, Fisher WS, Ewert KK, Li Y, Feinstein SC, Safinya CR. Mixtures of Intrinsically Disordered Neuronal Protein Tau and Anionic Liposomes Reveal Distinct Anionic Liposome-Tau Complexes Coexisting with Tau Liquid-Liquid Phase Separated Coacervates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.15.603342. [PMID: 39071287 PMCID: PMC11275723 DOI: 10.1101/2024.07.15.603342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Tau, an intrinsically disordered neuronal protein and polyampholyte with an overall positive charge, is a microtubule (MT) associated protein, which binds to anionic domains of MTs and suppresses their dynamic instability. Aberrant tau-MT interactions are implicated in Alzheimer's and other neurodegenerative diseases. Here, we studied the interactions between full length human protein tau and other negatively charged binding substrates, as revealed by differential-interference-contrast (DIC) and fluorescence microscopy. As a binding substrate, we chose anionic liposomes (ALs) containing either 1,2-dioleoyl-sn-glycero-3-phosphatidylserine (DOPS, -1e) or 1,2-dioleoyl-sn-glycero-3-phosphatidylglycerol (DOPG, -1e) mixed with zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) to mimic anionic plasma membranes of axons where tau resides. At low salt concentrations (0 to 10 mM KCl or NaCl) with minimal charge screening, reaction mixtures of tau and ALs resulted in the formation of distinct states of AL-tau complexes coexisting with liquid-liquid phase separated tau self-coacervates arising from the polyampholytic nature of tau containing cationic and anionic domains. AL-tau complexes exhibited distinct types of morphologies. This included, large ≈20-30 micron tau-decorated giant vesicles with additional smaller liposomes with bound tau attached to the giant vesicles, and tau-mediated finite-size assemblies of small liposomes. As the ionic strength of the solution was increased to near and above physiological salt concentrations for 1:1 electrolytes (≈150 mM), AL-tau complexes remained stable while tau self-coacervate droplets were found to dissolve indicative of breaking of (anionic/cationic) electrostatic bonds between tau chains due to increased charge screening. The findings are consistent with the hypothesis that distinct cationic domains of tau may interact with anionic lipid domains of the lumen facing monolayer of the axon plasma membrane suggesting the possibility of transient yet robust interactions at physiologically relevant ionic strengths.
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2
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Kohl PA, Song C, Fletcher BJ, Best RL, Tchounwou C, Garcia Arceo X, Chung PJ, Miller HP, Wilson L, Choi MC, Li Y, Feinstein SC, Safinya CR. Complexes of tubulin oligomers and tau form a viscoelastic intervening network cross-bridging microtubules into bundles. Nat Commun 2024; 15:2362. [PMID: 38491006 PMCID: PMC10943092 DOI: 10.1038/s41467-024-46438-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 02/28/2024] [Indexed: 03/18/2024] Open
Abstract
The axon-initial-segment (AIS) of mature neurons contains microtubule (MT) fascicles (linear bundles) implicated as retrograde diffusion barriers in the retention of MT-associated protein (MAP) tau inside axons. Tau dysfunction and leakage outside of the axon is associated with neurodegeneration. We report on the structure of steady-state MT bundles in varying concentrations of Mg2+ or Ca2+ divalent cations in mixtures containing αβ-tubulin, full-length tau, and GTP at 37 °C in a physiological buffer. A concentration-time kinetic phase diagram generated by synchrotron SAXS reveals a wide-spacing MT bundle phase (Bws), a transient intermediate MT bundle phase (Bint), and a tubulin ring phase. SAXS with TEM of plastic-embedded samples provides evidence of a viscoelastic intervening network (IN) of complexes of tubulin oligomers and tau stabilizing MT bundles. In this model, αβ-tubulin oligomers in the IN are crosslinked by tau's MT binding repeats, which also link αβ-tubulin oligomers to αβ-tubulin within the MT lattice. The model challenges whether the cross-bridging of MTs is attributed entirely to MAPs. Tubulin-tau complexes in the IN or bound to isolated MTs are potential sites for enzymatic modification of tau, promoting nucleation and growth of tau fibrils in tauopathies.
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Affiliation(s)
- Phillip A Kohl
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Chaeyeon Song
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Amorepacific R&I Center, Yongin, 17074, Republic of Korea
| | - Bretton J Fletcher
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Rebecca L Best
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Serimmune Inc., 150 Castilian Dr., Goleta, CA, 93117, USA
| | - Christine Tchounwou
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Ximena Garcia Arceo
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, San Diego, CA, 93106, USA
| | - Peter J Chung
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA
| | - Herbert P Miller
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Leslie Wilson
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Daejeon, 34141, Korea
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Stuart C Feinstein
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Cyrus R Safinya
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA.
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
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3
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Galesic A, Pan B, Ramirez J, Rhoades E, Pratt MR, Petersson EJ. Combining non-canonical amino acid mutagenesis and native chemical ligation for multiply modifying proteins: A case study of α-synuclein post-translational modifications. Methods 2023; 218:101-109. [PMID: 37549799 PMCID: PMC10657485 DOI: 10.1016/j.ymeth.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 08/09/2023] Open
Abstract
The Parkinson's disease associated protein α-synuclein (αS) has been found to contain numerous post-translational modifications (PTMs), in both physiological and pathological states. One PTM site of particular interest is serine 87, which is subject to both O-linked β-N-acetylglucosamine (gS) modification and phosphorylation (pS), with αS-pS87 enriched in Parkinson's disease. An often-overlooked aspect of these PTMs is their effect on the membrane-binding properties of αS, which are important to its role in regulating neurotransmitter release. Here, we show how one can study these effects by synthesizing αS constructs containing authentic PTMs and labels for single molecule fluorescence correlation spectroscopy measurements. We synthesize αS-gS87 and αS-pS87 by combining native chemical ligation with genetic code expansion approaches. We introduce the fluorophore by a click reaction with a non-canonical amino acid. Beyond the specific problem of PTM effects on αS, our studies highlight the value of this combination of methods for multiply modifying proteins.
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Affiliation(s)
- Ana Galesic
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
| | - Buyan Pan
- Department of Chemistry; University of Pennsylvania; 231 South 34th Street; Philadelphia, PA 19104, USA
| | - Jennifer Ramirez
- Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Elizabeth Rhoades
- Department of Chemistry; University of Pennsylvania; 231 South 34th Street; Philadelphia, PA 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Matthew R. Pratt
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
| | - E. James Petersson
- Department of Chemistry; University of Pennsylvania; 231 South 34th Street; Philadelphia, PA 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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4
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El Mammeri N, Dregni AJ, Duan P, Wang HK, Hong M. Microtubule-binding core of the tau protein. SCIENCE ADVANCES 2022; 8:eabo4459. [PMID: 35857846 PMCID: PMC9299549 DOI: 10.1126/sciadv.abo4459] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 06/07/2022] [Indexed: 05/15/2023]
Abstract
The protein tau associates with microtubules to maintain neuronal health. Posttranslational modifications of tau interfere with this binding, leading to tau aggregation in neurodegenerative disorders. Here, we use solid-state nuclear magnetic resonance (NMR) to investigate the structure of the microtubule-binding domain of tau. Wild-type tau that contains four microtubule-binding repeats and a pseudorepeat R' is studied. Complexed with taxol-stabilized microtubules, the immobilized residues exhibit well-resolved two-dimensional spectra that can be assigned to the amino-terminal region of R4 and the R' domain. When tau coassembles with tubulin to form unstable microtubules, the R' signals remain, whereas the R4 signals disappear, indicating that R' remains immobilized, whereas R4 becomes more mobile. Therefore, R' outcompetes the other four repeats to associate with microtubules. These NMR data, together with previous cryo-electron microscopy densities, indicate an extended conformation for microtubule-bound R'. R' contains the largest number of charged residues among all repeats, suggesting that charge-charge interaction drives tau-microtubule association.
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Affiliation(s)
- Nadia El Mammeri
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | | | - Pu Duan
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Harrison K. Wang
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
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5
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Barbolina MV. Dichotomous role of microtubule associated protein tau as a biomarker of response to and a target for increasing efficacy of taxane treatment in cancers of epithelial origin. Pharmacol Res 2021; 168:105585. [PMID: 33798735 PMCID: PMC8165012 DOI: 10.1016/j.phrs.2021.105585] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 03/25/2021] [Accepted: 03/26/2021] [Indexed: 12/19/2022]
Abstract
Cancer is the second leading cause of death worldwide, and the World Health Organization estimates that one in six deaths globally is due to cancer. Chemotherapy is one of the major modalities used to treat advanced cancers and their metastasis. However, the existence of acquired and intrinsic resistance to anti-cancer drugs often diminishes their therapeutic effect. In order to pre-select patients who could benefit the most from these treatments, the efforts of many research groups have been focused on identification of biomarkers of therapy response. Taxanes paclitaxel (Taxol) and docetaxel (Taxotere) have been introduced as chemotherapy for treatment of cancers of ovary in 1992 and breast in 1996, respectively. Since then, clinical use of taxanes has expanded to include lung, prostate, gastric, head and neck, esophageal, pancreatic, and cervical cancers, as well as Kaposi sarcoma. Several independent molecular mechanisms have been shown to support taxane chemoresistance. One such mechanism is dependent on microtubule associated protein tau. Tau binds to the same site on the inner side of the microtubules that is also occupied by paclitaxel or docetaxel, and several studies have demonstrated that low/no tau expression significantly correlated with better response to the taxane treatment, suggesting that levels of tau expression could have a predictive value in pre-selecting patient cohorts that are likely to benefit from the treatment. However, several other studies have found no correlation between tau expression and taxane response, introducing a controversy and precluding its wide use as a predictive biomarker. Based on the knowledge of tau biology accumulated thus far, in this review we attempt to critically analyze the studies that evaluated tau as a biomarker of taxane response. Further, we identify yet unknown aspects of tau biology understanding of which is necessary for improvement of development of tau as a biomarker of response and a target for increasing response to taxane treatment.
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Affiliation(s)
- Maria V Barbolina
- University of Illinois at Chicago, College of Pharmacy, Department of Pharmaceutical Sciences, 833 South Wood Street, Chicago, IL 60612, USA.
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6
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Weng J, Wang W. Dynamic multivalent interactions of intrinsically disordered proteins. Curr Opin Struct Biol 2020; 62:9-13. [DOI: 10.1016/j.sbi.2019.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/04/2019] [Accepted: 11/04/2019] [Indexed: 12/17/2022]
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7
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Dillon GM, Henderson JL, Bao C, Joyce JA, Calhoun M, Amaral B, King KW, Bajrami B, Rabah D. Acute inhibition of the CNS-specific kinase TTBK1 significantly lowers tau phosphorylation at several disease relevant sites. PLoS One 2020; 15:e0228771. [PMID: 32255788 PMCID: PMC7138307 DOI: 10.1371/journal.pone.0228771] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 11/24/2022] Open
Abstract
Hyperphosphorylated tau protein is a pathological hallmark of numerous neurodegenerative diseases and the level of tau pathology is correlated with the degree of cognitive impairment. Tau hyper-phosphorylation is thought to be an early initiating event in the cascade leading to tau toxicity and neuronal death. Inhibition of tau phosphorylation therefore represents an attractive therapeutic strategy. However, the widespread expression of most kinases and promiscuity of their substrates, along with poor selectivity of most kinase inhibitors, have resulted in systemic toxicities that have limited the advancement of tau kinase inhibitors into the clinic. We therefore focused on the CNS-specific tau kinase, TTBK1, and investigated whether selective inhibition of this kinase could represent a viable approach to targeting tau phosphorylation in disease. In the current study, we demonstrate that TTBK1 regulates tau phosphorylation using overexpression or knockdown of this kinase in heterologous cells and primary neurons. Importantly, we find that TTBK1-specific phosphorylation of tau leads to a loss of normal protein function including a decrease in tau-tubulin binding and deficits in tubulin polymerization. We then describe the use of a novel, selective small molecule antagonist, BIIB-TTBK1i, to study the acute effects of TTBK1 inhibition on tau phosphorylation in vivo. We demonstrate substantial lowering of tau phosphorylation at multiple sites implicated in disease, suggesting that TTBK1 inhibitors may represent an exciting new approach in the search for neurodegenerative disease therapies.
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Affiliation(s)
| | | | - Channa Bao
- Biogen, Cambridge, MA, United States of America
| | | | | | | | | | | | - Dania Rabah
- Biogen, Cambridge, MA, United States of America
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8
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Fung HYJ, McKibben KM, Ramirez J, Gupta K, Rhoades E. Structural Characterization of Tau in Fuzzy Tau:Tubulin Complexes. Structure 2020; 28:378-384.e4. [PMID: 31995742 DOI: 10.1016/j.str.2020.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 11/21/2019] [Accepted: 01/07/2020] [Indexed: 02/02/2023]
Abstract
Tau is a neuronal microtubule (MT)-associated protein of significant interest due to its association with several neurodegenerative disorders. Tau's intrinsic disorder and the dynamic nature of its interactions with tubulin and MTs make its structural characterization challenging. Here, we use an environmentally sensitive fluorophore as a site-specific probe of tau bound to soluble tubulin. Comparison of our results with a recently published tau:MT cryoelectron microscopy model reveals structural similarities between tubulin- and MT-bound tau. Analysis of residues across the repeat regions reveals a hierarchy in tubulin occupancy, which may be relevant to tau's ability to differentiate between tubulin and MTs. As binding to soluble tubulin is a critical first step in MT polymerization, our characterization of the structural features of tau in dynamic, fuzzy tau:tubulin assemblies advances our understanding of how tau functions in the cell and how function may be disrupted in disease.
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Affiliation(s)
- Ho Yee Joyce Fung
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kristen M McKibben
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jennifer Ramirez
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, Perelman School of Medicine at University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Elizabeth Rhoades
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at University of Pennsylvania, Philadelphia, PA 19104, USA.
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9
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Birol M, Melo AM. Untangling the Conformational Polymorphism of Disordered Proteins Associated With Neurodegeneration at the Single-Molecule Level. Front Mol Neurosci 2020; 12:309. [PMID: 31998071 PMCID: PMC6965022 DOI: 10.3389/fnmol.2019.00309] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/29/2019] [Indexed: 12/15/2022] Open
Abstract
A large fraction of the human genome encodes intrinsically disordered proteins/regions (IDPs/IDRs) that are involved in diverse cellular functions/regulation and dysfunctions. Moreover, several neurodegenerative disorders are associated with the pathological self-assembly of neuronal IDPs, including tau [Alzheimer's disease (AD)], α-synuclein [Parkinson's disease (PD)], and huntingtin exon 1 [Huntington's disease (HD)]. Therefore, there is an urgent and emerging clinical interest in understanding the physical and structural features of their functional and disease states. However, their biophysical characterization is inherently challenging by traditional ensemble techniques. First, unlike globular proteins, IDPs lack stable secondary/tertiary structures under physiological conditions and may interact with multiple and distinct biological partners, subsequently folding differentially, thus contributing to the conformational polymorphism. Second, amyloidogenic IDPs display a high aggregation propensity, undergoing complex heterogeneous self-assembly mechanisms. In this review article, we discuss the advantages of employing cutting-edge single-molecule fluorescence (SMF) techniques to characterize the conformational ensemble of three selected neuronal IDPs (huntingtin exon 1, tau, and α-synuclein). Specifically, we survey the versatility of these powerful approaches to describe their monomeric conformational ensemble under functional and aggregation-prone conditions, and binding to biological partners. Together, the information gained from these studies provides unique insights into the role of gain or loss of function of these disordered proteins in neurodegeneration, which may assist the development of new therapeutic molecules to prevent and treat these devastating human disorders.
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Affiliation(s)
- Melissa Birol
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Ana M Melo
- Centro de Química-Física Molecular- IN and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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10
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McKibben KM, Rhoades E. Independent tubulin binding and polymerization by the proline-rich region of Tau is regulated by Tau's N-terminal domain. J Biol Chem 2019; 294:19381-19394. [PMID: 31699899 DOI: 10.1074/jbc.ra119.010172] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 11/06/2019] [Indexed: 11/06/2022] Open
Abstract
Tau is an intrinsically disordered, microtubule-associated protein that has a role in regulating microtubule dynamics. Despite intensive research, the molecular mechanisms of Tau-mediated microtubule polymerization are poorly understood. Here we used single-molecule fluorescence to investigate the role of Tau's N-terminal domain (NTD) and proline-rich region (PRR) in regulating interactions of Tau with soluble tubulin. We assayed both full-length Tau isoforms and truncated variants for their ability to bind soluble tubulin and stimulate microtubule polymerization. We found that Tau's PRR is an independent tubulin-binding domain that has tubulin polymerization capacity. In contrast to the relatively weak interactions with tubulin mediated by sites distributed throughout Tau's microtubule-binding region (MTBR), resulting in heterogeneous Tau: tubulin complexes, the PRR bound tubulin tightly and stoichiometrically. Moreover, we demonstrate that interactions between the PRR and MTBR are reduced by the NTD through a conserved conformational ensemble. On the basis of these results, we propose that Tau's PRR can serve as a core tubulin-binding domain, whereas the MTBR enhances polymerization capacity by increasing the local tubulin concentration. Moreover, the NTD appears to negatively regulate tubulin-binding interactions of both of these domains. The findings of our study draw attention to a central role of the PRR in Tau function and provide mechanistic insight into Tau-mediated polymerization of tubulin.
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Affiliation(s)
- Kristen M McKibben
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Elizabeth Rhoades
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania 19104 .,Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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11
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Tan R, Lam AJ, Tan T, Han J, Nowakowski DW, Vershinin M, Simó S, Ori-McKenney KM, McKenney RJ. Microtubules gate tau condensation to spatially regulate microtubule functions. Nat Cell Biol 2019; 21:1078-1085. [PMID: 31481790 PMCID: PMC6748660 DOI: 10.1038/s41556-019-0375-5] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 07/18/2019] [Indexed: 01/18/2023]
Abstract
Tau is an abundant microtubule-associated protein in neurons. Tau aggregation into insoluble fibrils is a hallmark of Alzheimer's disease and other types of dementia1, yet the physiological state of tau molecules within cells remains unclear. Using single-molecule imaging, we directly observe that the microtubule lattice regulates reversible tau self-association, leading to localized, dynamic condensation of tau molecules on the microtubule surface. Tau condensates form selectively permissible barriers, spatially regulating the activity of microtubule-severing enzymes and the movement of molecular motors through their boundaries. We propose that reversible self-association of tau molecules, gated by the microtubule lattice, is an important mechanism of the biological functions of tau, and that oligomerization of tau is a common property shared between the physiological and disease-associated forms of the molecule.
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Affiliation(s)
- Ruensern Tan
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Aileen J Lam
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Tracy Tan
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA
| | - Jisoo Han
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, Davis, CA, USA
| | | | - Michael Vershinin
- Department of Physics & Astronomy, University of Utah, Salt Lake City, UT, USA
| | - Sergi Simó
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, Davis, CA, USA
| | | | - Richard J McKenney
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, USA.
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12
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Polyphosphate Initiates Tau Aggregation through Intra- and Intermolecular Scaffolding. Biophys J 2019; 117:717-728. [PMID: 31400913 DOI: 10.1016/j.bpj.2019.07.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/28/2019] [Accepted: 07/08/2019] [Indexed: 12/20/2022] Open
Abstract
The aggregation and deposition of tau is a hallmark of a class of neurodegenerative diseases called tauopathies. Despite intensive study, cellular and molecular factors that trigger tau aggregation are not well understood. Here, we provide evidence for two mechanisms relevant to the initiation of tau aggregation in the presence of cytoplasmic polyphosphates (polyP): changes in the conformational ensemble of monomer tau and noncovalent cross-linking of multiple tau monomers. We identified conformational changes throughout full-length tau, most notably diminishment of long-range interactions between the termini coupled with compaction of the microtubule binding and proline- rich regions. We found that while the proline-rich and microtubule binding regions both contain polyP binding sites, the proline-rich region is a requisite for compaction of the microtubule binding region upon binding. Additionally, both the magnitude of the conformational change and the aggregation of tau are dependent on the chain length of the polyP polymer. Longer polyP chains are more effective at intermolecular, noncovalent cross-linking of tau. These observations provide an understanding of the initial steps of tau aggregation through interaction with a physiologically relevant aggregation inducer.
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13
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Best RL, LaPointe NE, Liang J, Ruan K, Shade MF, Wilson L, Feinstein SC. Tau isoform-specific stabilization of intermediate states during microtubule assembly and disassembly. J Biol Chem 2019; 294:12265-12280. [PMID: 31266806 DOI: 10.1074/jbc.ra119.009124] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/24/2019] [Indexed: 01/27/2023] Open
Abstract
The microtubule (MT)-associated protein tau regulates the critical growing and shortening behaviors of MTs, and its normal activity is essential for neuronal development and maintenance. Accordingly, aberrant tau action is tightly associated with Alzheimer's disease and is genetically linked to several additional neurodegenerative diseases known as tauopathies. Although tau is known to promote net MT growth and stability, the precise mechanistic details governing its regulation of MT dynamics remain unclear. Here, we have used the slowly-hydrolyzable GTP analog, guanylyl-(α,β)-methylene-diphosphonate (GMPCPP), to examine the structural effects of tau at MT ends that may otherwise be too transient to observe. The addition of both four-repeat (4R) and three-repeat (3R) tau isoforms to pre-formed GMPCPP MTs resulted in the formation of extended, multiprotofilament-wide projections at MT ends. Furthermore, at temperatures too low for assembly of bona fide MTs, both tau isoforms promoted the formation of long spiral ribbons from GMPCPP tubulin heterodimers. In addition, GMPCPP MTs undergoing cold-induced disassembly in the presence of 4R tau (and to a much lesser extent 3R tau) also formed spirals. Finally, three pathological tau mutations known to cause neurodegeneration and dementia were differentially compromised in their abilities to stabilize MT disassembly intermediates. Taken together, we propose that tau promotes the formation/stabilization of intermediate states in MT assembly and disassembly by promoting both longitudinal and lateral tubulin-tubulin contacts. We hypothesize that these activities represent fundamental aspects of tau action that normally occur at the GTP-rich ends of GTP/GDP MTs and that may be compromised in neurodegeneration-causing tau variants.
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Affiliation(s)
- Rebecca L Best
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106
| | - Nichole E LaPointe
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106
| | - Jiahao Liang
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106
| | - Kevin Ruan
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106
| | - Madeleine F Shade
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106
| | - Leslie Wilson
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106
| | - Stuart C Feinstein
- Neuroscience Research Institute and Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106.
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14
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Venkatramani A, Panda D. Regulation of neuronal microtubule dynamics by tau: Implications for tauopathies. Int J Biol Macromol 2019; 133:473-483. [DOI: 10.1016/j.ijbiomac.2019.04.120] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 12/13/2022]
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15
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Identification of N-linked glycans as specific mediators of neuronal uptake of acetylated α-Synuclein. PLoS Biol 2019; 17:e3000318. [PMID: 31211781 PMCID: PMC6599126 DOI: 10.1371/journal.pbio.3000318] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 06/28/2019] [Accepted: 05/28/2019] [Indexed: 11/19/2022] Open
Abstract
Cell-to-cell transmission of toxic forms of α-Synuclein (αS) is thought to underlie disease progression in Parkinson disease. αS in humans is constitutively N-terminally acetylated (αSacetyl), although the impact of this modification is relatively unexplored. Here, we report that αSacetyl is more effective at inducing intracellular aggregation in primary neurons than unmodified αS (αSun). We identify complex N-linked glycans as binding partners for αSacetyl and demonstrate that cellular internalization of αSacetyl is reduced significantly upon cleavage of extracellular N-linked glycans, but not other carbohydrates. We verify binding of αSacetyl to N-linked glycans in vitro, using both isolated glycans and cell-derived proteoliposomes. Finally, we identify neurexin 1β, a neuronal glycoprotein, as capable of driving glycan-dependent uptake of αSacetyl. Importantly, our results are specific to αSacetyl because αSun does not demonstrate sensitivity for N-linked glycans in any of our assays. Our study identifies extracellular N-linked glycans—and the glycoprotein neurexin 1β specifically—as key modulators of neuronal uptake of αSacetyl, drawing attention to the potential therapeutic value of αSacetyl-glycan interactions. This study identifies extracellular N-linked glycans — and the glycoprotein neurexin 1β — as key modulators of neuronal uptake of N-terminally acetylated α-Synuclein, emphasising the potential therapeutic value of α-Synuclein-glycan interactions.
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16
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Fuxreiter M. Fold or not to fold upon binding - does it really matter? Curr Opin Struct Biol 2018; 54:19-25. [PMID: 30340123 DOI: 10.1016/j.sbi.2018.09.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 09/20/2018] [Accepted: 09/21/2018] [Indexed: 12/14/2022]
Abstract
Protein interactions are usually determined by well-defined contact patterns. In this scenario, structuring of the interface is a prerequisite, which takes place prior or coupled to binding. Recent data, however, indicate plasticity of the templated folding pathway as well as considerable variations: polymorphism or dynamics in the bound-state. Conformational fluctuations in both cases are modulated by non-native, transient contacts, which complement suboptimal binding motifs to improve affinity. Here I discuss both templated folding and fuzzy binding mechanisms and propose a uniform scheme.
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Affiliation(s)
- Monika Fuxreiter
- MTA-DE Laboratory of Protein Dynamics, Department of Biochemistry and Molecular Biology, University of Debrecen, Hungary.
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17
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Shin S, Lim S, Jeong H, Kwan LT, Kim YK. Visualization of Tau⁻Tubulin Interaction in a Living Cell Using Bifluorescence Complementation Technique. Int J Mol Sci 2018; 19:ijms19102978. [PMID: 30274285 PMCID: PMC6213793 DOI: 10.3390/ijms19102978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/22/2018] [Accepted: 09/27/2018] [Indexed: 11/17/2022] Open
Abstract
Tau is a neuron-specific microtubule-binding protein that stabilizes microtubules. It is generally thought that highly phosphorylated tau dissociates from microtubules and becomes insoluble aggregates, leading to neuronal degeneration. Due to the implication of tau aggregation in neurodegenerative disorders, including Alzheimer’s disease, great efforts have been made to identify the tau aggregation process. However, tau interaction with tubulin during the aggregation process remains largely unknown. To scrutinize the tau-tubulin interaction, we generated a cell model that enables visualization of the tau-tubulin interaction in a living cell using the Bifluorescence Complementation (BiFC) Technique. Upon diverse chemical stimulation that induced tau pathology, tau-tubulin BiFC cells showed significantly increased levels of BiFC fluorescence, indicating that tau aggregates together with tubulin. Our results suggest that tubulin should be considered as a key component in the tau aggregation process.
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Affiliation(s)
- Seulgi Shin
- Korea Institute of Science and Technology (KIST), Brain Science Institute, Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Seoul 02792, Korea.
| | - Sungsu Lim
- Korea Institute of Science and Technology (KIST), Brain Science Institute, Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Seoul 02792, Korea.
| | - Hyeanjeong Jeong
- Korea Institute of Science and Technology (KIST), Brain Science Institute, Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Seoul 02792, Korea.
- Department of Life Science, Korea University, Seoul 02841, Korea.
| | - Li Ting Kwan
- Korea Institute of Science and Technology (KIST), Brain Science Institute, Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Seoul 02792, Korea.
- Department of Neuroscience, Wellesley College, Wellesley, MA 02481, USA.
| | - Yun Kyung Kim
- Korea Institute of Science and Technology (KIST), Brain Science Institute, Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Seoul 02792, Korea.
- Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Daejeon 34113, Korea.
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18
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Miyasaka T, Shinzaki Y, Yoshimura S, Yoshina S, Kage-Nakadai E, Mitani S, Ihara Y. Imbalanced Expression of Tau and Tubulin Induces Neuronal Dysfunction in C. elegans Models of Tauopathy. Front Neurosci 2018; 12:415. [PMID: 29973863 PMCID: PMC6019497 DOI: 10.3389/fnins.2018.00415] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/31/2018] [Indexed: 12/12/2022] Open
Abstract
Tauopathy is a type of dementia defined by the accumulation of filamentous tau inclusions in neural cells. Most types of dementia in the elderly, including Alzheimer's disease, are tauopathies. Although it is believed that tau protein abnormalities and/or the loss of its functions results in neurodegeneration and dementia, the mechanism of tauopathy remains obscure. Loss of microtubules and/or tubulin is a known consequence of tau accumulating in neurons in Alzheimer's disease. In other words, there is an excess level of tau relative to tubulin in tauopathy neurons. To test whether this imbalance of tau and tubulin expression results in the neurotoxicity of tau, we developed several transgenic C. elegans lines that express human tau at various levels in pan-neurons. These worms showed behavioral abnormalities in a tau expression-dependent manner. The knockdown of a tubulin-specific chaperon, or a subset of tubulin, led to enhanced tau toxicity even in low-expressing tau-transgenic worms that showed no abnormal behaviors. In addition, the suppression of tau expression in tubulin knockdown worms rescued neuronal dysfunction. Thus, not only the overexpression of tau but also a reduction in tubulin can trigger the neurotoxicity of tau. Tau expressed in worms was also highly phosphorylated and largely bound to tubulin dimers rather than microtubules. Relative amount of tubulin-unbound tau was increased in high-expressing tau-transgenic worms showing tau toxicity. We further demonstrated that tau aggregation was inhibited by co-incubation of purified tubulin in vitro, meaning sufficient amounts of tubulin can protect against the formation of tau inclusions. These results suggest that the expression ratio of tau to tubulin may be a determinant of the tauopathy cascade.
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Affiliation(s)
- Tomohiro Miyasaka
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Yuki Shinzaki
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Satomi Yoshimura
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Sawako Yoshina
- Department of Physiology, School of Medicine, Tokyo Women’s Medical University, Tokyo, Japan
| | - Eriko Kage-Nakadai
- Department of Physiology, School of Medicine, Tokyo Women’s Medical University, Tokyo, Japan
- Graduate School of Human Life Science, Osaka City University, Osaka, Japan
| | - Shohei Mitani
- Department of Physiology, School of Medicine, Tokyo Women’s Medical University, Tokyo, Japan
| | - Yasuo Ihara
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
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19
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Hernández-Vega A, Braun M, Scharrel L, Jahnel M, Wegmann S, Hyman BT, Alberti S, Diez S, Hyman AA. Local Nucleation of Microtubule Bundles through Tubulin Concentration into a Condensed Tau Phase. Cell Rep 2018; 20:2304-2312. [PMID: 28877466 PMCID: PMC5828996 DOI: 10.1016/j.celrep.2017.08.042] [Citation(s) in RCA: 228] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 07/23/2017] [Accepted: 08/10/2017] [Indexed: 11/16/2022] Open
Abstract
Non-centrosomal microtubule bundles play important roles in cellular organization and function. Although many diverse proteins are known that can bundle microtubules, biochemical mechanisms by which cells could locally control the nucleation and formation of microtubule bundles are understudied. Here, we demonstrate that the concentration of tubulin into a condensed, liquid-like compartment composed of the unstructured neuronal protein tau is sufficient to nucleate microtubule bundles. We show that, under conditions of macro-molecular crowding, tau forms liquid-like drops. Tubulin partitions into these drops, efficiently increasing tubulin concentration and driving the nucleation of microtubules. These growing microtubules form bundles, which deform the drops while remaining enclosed by diffusible tau molecules exhibiting a liquid-like behavior. Our data suggest that condensed compartments of microtubule bundling proteins could promote the local formation of microtubule bundles in neurons by acting as non-centrosomal microtubule nucleation centers and that liquid-like tau encapsulation could provide both stability and plasticity to long axonal microtubule bundles.
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Affiliation(s)
| | - Marcus Braun
- B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Dresden 01307, Germany; Institute of Biotechnology CAS, BIOCEV, Vestec 25250, Czech Republic
| | - Lara Scharrel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Dresden 01307, Germany
| | - Marcus Jahnel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; BIOTEC, Biotechnology Center of the Technische Universität Dresden, Dresden 01307, Germany
| | - Susanne Wegmann
- Department Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Bradley T Hyman
- Department Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Stefan Diez
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Dresden 01307, Germany.
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
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20
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Li XH, Chavali PL, Pancsa R, Chavali S, Babu MM. Function and Regulation of Phase-Separated Biological Condensates. Biochemistry 2018; 57:2452-2461. [PMID: 29392932 DOI: 10.1021/acs.biochem.7b01228] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Achieving functional specificity while minimizing cost to fitness is a key constraint during evolution. Formation of biological condensates by liquid-liquid phase separation (LLPS) appears to serve as an important regulatory mechanism to generate moderate specificity in molecular recognition while maintaining a reasonable cost for fitness in terms of design complexity. Formation of biological condensates serves as a unique mechanism of molecular recognition achieving some level of specificity without a huge cost to fitness. Rapid formation of biological condensates in vivo induced by specific cellular or environmental triggers has been shown to be an important mechanism for increasing cellular fitness. Here we discuss the functions and regulation of biological condensates, especially those formed by LLPS, involving interactions between proteins and nucleic acids. These condensates are spatially isolated within the cytosol or nucleus and can facilitate specific biochemical functions under conditions such as stress. The misregulation of biological condensates resulting in nondynamic aggregates has been implicated in a number of diseases. Understanding the functional importance of biological condensates and their regulation opens doors for development of therapies targeting dysfunctional biological condensates, as well as spatiotemporal engineering of functions in cells.
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Affiliation(s)
- Xiao-Han Li
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge , U.K
| | - Pavithra L Chavali
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge , U.K
| | - Rita Pancsa
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge , U.K
| | - Sreenivas Chavali
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge , U.K
| | - M Madan Babu
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge , U.K
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21
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IDPs in macromolecular complexes: the roles of multivalent interactions in diverse assemblies. Curr Opin Struct Biol 2018; 49:36-43. [PMID: 29306779 DOI: 10.1016/j.sbi.2017.12.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 01/21/2023]
Abstract
Intrinsically disordered proteins (IDPs) have critical roles in a diverse array of cellular functions. Of relevance here is that they are components of macromolecular complexes, where their conformational flexibility helps mediate interactions with binding partners. IDPs often interact with their binding partners through short sequence motifs, commonly repeated within the disordered regions. As such, multivalent interactions are common for IDPs and their binding partners within macromolecular complexes. Here we discuss the importance of IDP multivalency in three very different macromolecular assemblies: biomolecular condensates, the nuclear pore, and the cytoskeleton.
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