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Rai D, Song Y, Hua S, Stecker K, Monster JL, Yin V, Stucchi R, Xu Y, Zhang Y, Chen F, Katrukha EA, Altelaar M, Heck AJR, Wieczorek M, Jiang K, Akhmanova A. CAMSAPs and nucleation-promoting factors control microtubule release from γ-TuRC. Nat Cell Biol 2024; 26:404-420. [PMID: 38424271 PMCID: PMC10940162 DOI: 10.1038/s41556-024-01366-2] [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: 08/03/2022] [Accepted: 01/26/2024] [Indexed: 03/02/2024]
Abstract
γ-Tubulin ring complex (γ-TuRC) is the major microtubule-nucleating factor. After nucleation, microtubules can be released from γ-TuRC and stabilized by other proteins, such as CAMSAPs, but the biochemical cross-talk between minus-end regulation pathways is poorly understood. Here we reconstituted this process in vitro using purified components. We found that all CAMSAPs could bind to the minus ends of γ-TuRC-attached microtubules. CAMSAP2 and CAMSAP3, which decorate and stabilize growing minus ends but not the minus-end tracking protein CAMSAP1, induced microtubule release from γ-TuRC. CDK5RAP2, a γ-TuRC-interactor, and CLASP2, a regulator of microtubule growth, strongly stimulated γ-TuRC-dependent microtubule nucleation, but only CDK5RAP2 suppressed CAMSAP binding to γ-TuRC-anchored minus ends and their release. CDK5RAP2 also improved selectivity of γ-tubulin-containing complexes for 13- rather than 14-protofilament microtubules in microtubule-capping assays. Knockout and overexpression experiments in cells showed that CDK5RAP2 inhibits the formation of CAMSAP2-bound microtubules detached from the microtubule-organizing centre. We conclude that CAMSAPs can release newly nucleated microtubules from γ-TuRC, whereas nucleation-promoting factors can differentially regulate this process.
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Affiliation(s)
- Dipti Rai
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Yinlong Song
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Shasha Hua
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Kelly Stecker
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Jooske L Monster
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Victor Yin
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Riccardo Stucchi
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Yixin Xu
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zürich, Zurich, Switzerland
| | - Yaqian Zhang
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Fangrui Chen
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Eugene A Katrukha
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Michal Wieczorek
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zürich, Zurich, Switzerland
| | - Kai Jiang
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China.
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China.
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands.
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Park J, Xie Y, Miller KG, De Camilli P, Yogev S. End-binding protein 1 promotes specific motor-cargo association in the cell body prior to axonal delivery of dense core vesicles. Curr Biol 2023; 33:3851-3864.e7. [PMID: 37586371 PMCID: PMC10529979 DOI: 10.1016/j.cub.2023.07.052] [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: 12/21/2022] [Revised: 05/25/2023] [Accepted: 07/25/2023] [Indexed: 08/18/2023]
Abstract
Axonal transport is key to neuronal function. Efficient transport requires specific motor-cargo association in the soma, yet the mechanisms regulating this early step remain poorly understood. We found that EBP-1, the C. elegans ortholog of the canonical-microtubule-end-binding protein EB1, promotes the specific association between kinesin-3/KIF1A/UNC-104 and dense core vesicles (DCVs) prior to their axonal delivery. Using single-neuron, in vivo labeling of endogenous cargo and EBs, we observed reduced axonal abundance and reduced secretion of DCV cargo, but not other KIF1A/UNC-104 cargoes, in ebp-1 mutants. This reduction could be traced back to fewer exit events from the cell body, where EBP-1 colocalized with the DCV sorting machinery at the trans Golgi, suggesting that this is the site of EBP-1 function. EBP-1 calponin homology (CH) domain was required for directing microtubule growth on the Golgi, and mammalian EB1 interacted with KIF1A in an EBH-domain-dependent manner. Loss- and gain-of-function experiments suggest a model in which both kinesin-3 binding and guidance of microtubule growth at the trans Golgi by EBP-1 promote motor-cargo association at sites of DCV biogenesis. In support of this model, tethering either EBP-1 or a kinesin-3/KIF1A/UNC-104-interacting domain from an unrelated protein to the Golgi restored the axonal abundance of DCV proteins in ebp-1 mutants. These results uncover an unexpected role for a microtubule-associated protein and provide insights into how specific kinesin-3 cargo is delivered to the axon.
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Affiliation(s)
- Junhyun Park
- Department of Neuroscience, Yale School of Medicine, 295 Congress Ave, New Haven, CT 06510, USA
| | - Yi Xie
- Department of Neuroscience, Yale School of Medicine, 295 Congress Ave, New Haven, CT 06510, USA
| | - Kenneth G Miller
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, 825 N. E. 13th St, Oklahoma City, OK 73104, USA
| | - Pietro De Camilli
- Department of Neuroscience, Yale School of Medicine, 295 Congress Ave, New Haven, CT 06510, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Yale School of Medicine, 295 Congress Ave, New Haven, CT 06510, USA; Howard Hughes Medical Institute, Yale University School of Medicine, 295 Congress Ave, New Haven, CT 06510, USA
| | - Shaul Yogev
- Department of Neuroscience, Yale School of Medicine, 295 Congress Ave, New Haven, CT 06510, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA.
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3
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MAPRE2 regulates the first meiotic progression in mouse oocytes. Exp Cell Res 2022; 416:113135. [DOI: 10.1016/j.yexcr.2022.113135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 03/30/2022] [Accepted: 04/01/2022] [Indexed: 11/22/2022]
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4
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Liao M, Kuo YW, Howard J. Counting fluorescently labeled proteins in tissues in the spinning disk microscope using single-molecule calibrations. Mol Biol Cell 2022; 33:ar48. [PMID: 35323029 PMCID: PMC9265152 DOI: 10.1091/mbc.e21-12-0618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Quantification of molecular numbers and concentrations in living cells is critical for testing models of complex biological phenomena. Counting molecules in cells requires estimation of the fluorescence intensity of single molecules, which is generally limited to imaging near cell surfaces, in isolated cells, or where motions are diffusive. To circumvent this difficulty, we have devised a calibration technique for spinning–disk confocal microscopy, commonly used for imaging in tissues, that uses single–step bleaching kinetics to estimate the single–fluorophore intensity. To cross–check our calibrations, we compared the brightness of fluorophores in the SDC microscope to those in the total internal reflection and epifluorescence microscopes. We applied this calibration method to quantify the number of end–binding protein 1 (EB1)–eGFP in the comets of growing microtubule ends and to measure the cytoplasmic concentration of EB1–eGFP in sensory neurons in fly larvae. These measurements allowed us to estimate the dissociation constant of EB1–eGFP from the microtubules as well as the GTP–tubulin cap size. Our results show the unexplored potential of single–molecule imaging using spinning–disk confocal microscopy and provide a straightforward method to count the absolute number of fluorophores in tissues that can be applied to a wide range of biological systems and imaging techniques.
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Affiliation(s)
- Maijia Liao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Yin-Wei Kuo
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
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5
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Mangon A, Salaün D, Bouali ML, Kuzmić M, Quitard S, Thuault S, Isnardon D, Audebert S, Puech PH, Verdier-Pinard P, Badache A. iASPP contributes to cell cortex rigidity, mitotic cell rounding, and spindle positioning. J Cell Biol 2021; 220:212730. [PMID: 34705028 PMCID: PMC8562848 DOI: 10.1083/jcb.202012002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 08/03/2021] [Accepted: 09/19/2021] [Indexed: 12/27/2022] Open
Abstract
iASPP is a protein mostly known as an inhibitor of p53 pro-apoptotic activity and a predicted regulatory subunit of the PP1 phosphatase, which is often overexpressed in tumors. We report that iASPP associates with the microtubule plus-end binding protein EB1, a central regulator of microtubule dynamics, via an SxIP motif. iASPP silencing or mutation of the SxIP motif led to defective microtubule capture at the cortex of mitotic cells, leading to abnormal positioning of the mitotic spindle. These effects were recapitulated by the knockdown of the membrane-to-cortex linker Myosin-Ic (Myo1c), which we identified as a novel partner of iASPP. Moreover, iASPP or Myo1c knockdown cells failed to round up upon mitosis because of defective cortical stiffness. We propose that by increasing cortical rigidity, iASPP helps cancer cells maintain a spherical geometry suitable for proper mitotic spindle positioning and chromosome partitioning.
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Affiliation(s)
- Aurélie Mangon
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Danièle Salaün
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Mohamed Lala Bouali
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Mira Kuzmić
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Sabine Quitard
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Sylvie Thuault
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Daniel Isnardon
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Stéphane Audebert
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Pierre-Henri Puech
- Laboratoire Adhésion et Inflammation, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Aix Marseille Université, Turing Center for Living Systems, Marseille, France
| | - Pascal Verdier-Pinard
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
| | - Ali Badache
- Centre de Recherche en Cancérologie de Marseille, Institut National de la Santé et de la Recherche Médicale, Institut Paoli-Calmettes, Aix-Marseille Université, Centre National de la Recherche Scientifique, Marseille, France
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6
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Ayyappan S, Dharan PS, Krishnan A, Marira RR, Lambert M, Manna TK, Vijayan V. SxIP binding disrupts the constitutive homodimer interface of EB1 and stabilizes EB1 monomer. Biophys J 2021; 120:2019-2029. [PMID: 33737159 DOI: 10.1016/j.bpj.2021.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/16/2021] [Accepted: 03/01/2021] [Indexed: 11/16/2022] Open
Abstract
SxIP is a microtubule tip localizing signal found in many +TIP proteins that bind to the hydrophobic cavity of the C-terminal domain of end binding protein 1 (EB1) and then positively regulate the microtubule plus-end tracking of EBs. However, the exact mechanism of microtubule activation of EBs in the presence of SxIP signaling motif is not known. Here, we studied the effect of SxIP peptide on the native conformation of EB1 in solution. Using various NMR experiments, we found that SxIP peptide promoted the dissociation of natively formed EB1 dimer. We also discovered that I224A mutation of EB1 resulted in an unfolded C-terminal domain, which upon binding with the SxIP motif folded to its native structure. Molecular dynamics simulations also confirmed the relative structural stability of EB1 monomer in the SxIP bound state. Residual dipolar couplings and heteronuclear NOE analysis suggested that the binding of SxIP peptide at the C-terminal domain of EB1 decreased the dynamics and conformational flexibility of the N-terminal domain involved in EB1-microtubule interaction. The SxIP-induced disruption of the dimeric interactions in EB1, coupled with the reduction in conformational flexibility of the N-terminal domain of EB1, might facilitate the microtubule association of EB1.
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Affiliation(s)
- Shine Ayyappan
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Pooja S Dharan
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Arya Krishnan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Renjith R Marira
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Mahil Lambert
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Tapas K Manna
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India
| | - Vinesh Vijayan
- School of Chemistry, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, India.
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7
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Wang L, Yan M, Wu S, Mao B, Wong CKC, Ge R, Sun F, Cheng CY. Microtubule Cytoskeleton and Spermatogenesis-Lesson From Studies of Toxicant Models. Toxicol Sci 2020; 177:305-315. [PMID: 32647867 PMCID: PMC7548287 DOI: 10.1093/toxsci/kfaa109] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Studies have shown that mammalian testes, in particular the Sertoli cells, are highly susceptible to exposure of environmental toxicants, such as cadmium, perfluorooctanesulfonate, phthalates, 2,5-hexanedione and bisphenol A. However, important studies conducted by reproductive toxicologists and/or biologists in the past have been treated as toxicology reports per se. Yet, many of these studies provided important mechanistic insights on the toxicant-induced testis injury and reproductive dysfunction, relevant to the biology of the testis and spermatogenesis. Furthermore, recent studies have shown that findings obtained from toxicant models are exceedingly helpful tools to unravel the biology of testis function in particular spermatogenesis, including specific cellular events associated with spermatid transport to support spermiogenesis and spermiation. In this review, we critically evaluate some recent data, focusing primarily on the molecular structure and role of microtubules in cellular function, illustrating the importance of toxicant models to unravel the biology of microtubule cytoskeleton in supporting spermatogenesis, well beyond information on toxicology. These findings have opened up some potential areas of research which should be carefully evaluated in the years to come.
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Affiliation(s)
- Lingling Wang
- The Second Affiliated Hospital and Yuying Children’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Ming Yan
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Siwen Wu
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Baiping Mao
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Chris K C Wong
- Department of Biology, Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong, China
| | - Renshan Ge
- The Second Affiliated Hospital and Yuying Children’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Fei Sun
- Institute of Reproductive Medicine, Nantong University School of Medicine, Nantong, Jiangsu 226001, China
| | - C Yan Cheng
- The Second Affiliated Hospital and Yuying Children’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Institute of Reproductive Medicine, Nantong University School of Medicine, Nantong, Jiangsu 226001, China
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8
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Activity-dependent neuroprotective protein (ADNP)-end-binding protein (EB) interactions regulate microtubule dynamics toward protection against tauopathy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 177:65-90. [PMID: 33453943 DOI: 10.1016/bs.pmbts.2020.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The 1102-amino-acid activity-dependent neuroprotective protein (ADNP) was originally discovered by expression cloning through the immunological identification of its 8-amino-acid sequence NAPVSIPQ (NAP), constituting the smallest active neuroprotective fragment of the protein. ADNP expression is essential for brain formation and cognitive function and is dysregulated in a variety of neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, and schizophrenia). ADNP has been found to be mutated in autism, with an estimated prevalence of 0.17% (together, these autism cases now constitute ADNP syndrome cases) and our recent results showed somatic mutations in ADNP in Alzheimer's disease brains correlating with tauopathy. Furthermore, Adnp haploinsufficiency in mice causes an age-dependent reduction in cognitive functions coupled with tauopathy-like features such as an increased formation of tangle-like structures, defective axonal transport, and Tau hyperphosphorylation. ADNP and its derived peptides, NAP and SKIP, directly interact with end-binding proteins (EBs), which decorate plus-tips of the growing axonal cytoskeleton-microtubules (MTs). Functionally, NAP and SKIP are neuroprotective and stimulate axonal transport. Clinical trials have suggested the potential efficacy of NAP (davunetide, CP201) for improving cognitive performance/functional activities of daily living in amnestic mild cognitive impairment (aMCI) and schizophrenia patients, respectively. However, NAP was not found to be an effective treatment (though well-tolerated) for progressive supranuclear palsy (PSP) patients. Here we review the molecular mechanism of NAP activity on MTs and how NAP modulates the MT-Tau-EBs crosstalk. We offer a molecular explanation for the different protective potency of NAP in selected tauopathies (aMCI vs. PSP) expressing different ratios/pathologies of the alternatively spliced Tau mRNA and its resulting protein (aMCI expressing similar quantities of the dynamic Tau 3-MT binding isoform (Tau3R) and the Tau 4-MT binding isoform (Tau4R) and PSP enriched in Tau4R pathology). We reveal the direct effect of truncated ADNPs (resulting from de novo autism and newly discovered Alzheimer's disease-related somatic mutations) on MT dynamics. We show that the peptide SKIP affects MT dynamics and MT-Tau association. Since MT impairment is linked with neurodegenerative and neurodevelopmental conditions, the current study implicates a paucity/dysregulation of MT-interacting endogenous proteins, like ADNP, as a contributing mechanism and provides hope for NAP and SKIP as MT-modulating drug candidates.
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9
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Deciphering the Enigma: NAP (CP201) the Active ADNP Drug Candidate Enters Cells by Dynamin-Associated Endocytosis. J Mol Neurosci 2020; 70:993-998. [DOI: 10.1007/s12031-020-01632-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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10
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Abdelkarim H, Hitchinson B, Qu X, Banerjee A, Komarova YA, Gaponenko V. NMR resonance assignment and structure prediction of the C-terminal domain of the microtubule end-binding protein 3. PLoS One 2020; 15:e0232338. [PMID: 32421702 PMCID: PMC7233555 DOI: 10.1371/journal.pone.0232338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 04/13/2020] [Indexed: 11/29/2022] Open
Abstract
End-binding proteins (EBs) associate with the growing microtubule plus ends to regulate microtubule dynamics as well as the interaction with intracellular structures. EB3 contributes to pathological vascular leakage through interacting with the inositol 1,4,5-trisphosphate receptor 3 (IP3R3), a calcium channel located at the endoplasmic reticulum membrane. The C-terminal domain of EB3 (residues 200–281) is functionally important for this interaction because it contains the effector binding sites, a prerequisite for EB3 activity and specificity. Structural data for this domain is limited. Here, we report the backbone chemical shift assignments for the human EB3 C-terminal domain and computationally explore its EB3 conformations. Backbone assignments, along with computational models, will allow future investigation of EB3 structural dynamics, interactions with effectors, and will facilitate the development of novel EB3 inhibitors.
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Affiliation(s)
- Hazem Abdelkarim
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Ben Hitchinson
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Xinyan Qu
- Department of Pharmacology and the Center for Lung Biology, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Avik Banerjee
- Department of Chemistry, University of Illinois, Chicago, IL, United States of America
| | - Yulia A. Komarova
- Department of Pharmacology and the Center for Lung Biology, University of Illinois at Chicago, Chicago, IL, United States of America
- * E-mail: (YAK); (VG)
| | - Vadim Gaponenko
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America
- * E-mail: (YAK); (VG)
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11
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Mao BP, Ge R, Cheng CY. Role of microtubule +TIPs and -TIPs in spermatogenesis – Insights from studies of toxicant models. Reprod Toxicol 2020; 91:43-52. [DOI: 10.1016/j.reprotox.2019.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/10/2019] [Accepted: 11/18/2019] [Indexed: 12/19/2022]
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12
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Zheng J, Liu H, Zhu L, Chen Y, Zhao H, Zhang W, Li F, Xie L, Yan X, Zhu X. Microtubule-bundling protein Spef1 enables mammalian ciliary central apparatus formation. J Mol Cell Biol 2019; 11:67-77. [PMID: 30535028 DOI: 10.1093/jmcb/mjy014] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 02/22/2018] [Indexed: 01/10/2023] Open
Abstract
Cilia are cellular protrusions containing nine microtubule (MT) doublets and function to propel cell movement or extracellular liquid flow through beating or sense environmental stimuli through signal transductions. Cilia require the central pair (CP) apparatus, consisting of two CP MTs covered with projections of CP proteins, for planar strokes. How the CP MTs of such '9 + 2' cilia are constructed, however, remains unknown. Here we identify Spef1, an evolutionarily conserved microtubule-bundling protein, as a core CP MT regulator in mammalian cilia. Spef1 was selectively expressed in mammalian cells with 9 + 2 cilia and specifically localized along the CP. Its depletion in multiciliated mouse ependymal cells by RNAi completely abolished the CP MTs and markedly attenuated ciliary localizations of CP proteins such as Hydin and Spag6, resulting in rotational beat of the ependymal cilia. Spef1, which binds to MTs through its N-terminal calponin-homologous domain, formed homodimers through its C-terminal coiled coil region to bundle and stabilize MTs. Disruption of either the MT-binding or the dimerization activity abolished the ability of exogenous Spef1 to restore the structure and functions of the CP apparatus. We propose that Spef1 bundles and stabilizes central MTs to enable the assembly and functions of the CP apparatus.
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Affiliation(s)
- Jianqun Zheng
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
- University of Chinese Academy of Sciences, Shanghai, China
| | - Hao Liu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
- University of Chinese Academy of Sciences, Shanghai, China
| | - Lei Zhu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
- University of Chinese Academy of Sciences, Shanghai, China
| | - Yawen Chen
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
- University of Chinese Academy of Sciences, Shanghai, China
| | - Huijie Zhao
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
| | - Wei Zhang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
| | - Fan Li
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
- University of Chinese Academy of Sciences, Shanghai, China
| | - Lele Xie
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
| | - Xiumin Yan
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai0, China
- University of Chinese Academy of Sciences, Shanghai, China
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13
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Aher A, Kok M, Sharma A, Rai A, Olieric N, Rodriguez-Garcia R, Katrukha EA, Weinert T, Olieric V, Kapitein LC, Steinmetz MO, Dogterom M, Akhmanova A. CLASP Suppresses Microtubule Catastrophes through a Single TOG Domain. Dev Cell 2018; 46:40-58.e8. [PMID: 29937387 PMCID: PMC6035287 DOI: 10.1016/j.devcel.2018.05.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 04/13/2018] [Accepted: 05/25/2018] [Indexed: 01/05/2023]
Abstract
The dynamic instability of microtubules plays a key role in controlling their organization and function, but the cellular mechanisms regulating this process are poorly understood. Here, we show that cytoplasmic linker-associated proteins (CLASPs) suppress transitions from microtubule growth to shortening, termed catastrophes, including those induced by microtubule-destabilizing agents and physical barriers. Mammalian CLASPs encompass three TOG-like domains, TOG1, TOG2, and TOG3, none of which bind to free tubulin. TOG2 is essential for catastrophe suppression, whereas TOG3 mildly enhances rescues but cannot suppress catastrophes. These functions are inhibited by the C-terminal domain of CLASP2, while the TOG1 domain can release this auto-inhibition. TOG2 fused to a positively charged microtubule-binding peptide autonomously accumulates at growing but not shrinking ends, suppresses catastrophes, and stimulates rescues. CLASPs suppress catastrophes by stabilizing growing microtubule ends, including incomplete ones, preventing their depolymerization and promoting their recovery into complete tubes. TOG2 domain is the key determinant of these activities. CLASPs potently suppress microtubule catastrophes induced by different mechanisms CLASPs act by stabilizing growing microtubule ends, including incomplete ones CLASP2 TOG-like domain, TOG2, is necessary and sufficient for catastrophe inhibition TOG2 fused to a positively charged peptide accumulates at growing microtubule ends
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Affiliation(s)
- Amol Aher
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Maurits Kok
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Ashwani Sharma
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Ankit Rai
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Natacha Olieric
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Ruddi Rodriguez-Garcia
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Eugene A Katrukha
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Tobias Weinert
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Vincent Olieric
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Lukas C Kapitein
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland; University of Basel, Biozentrum, 4056 Basel, Switzerland
| | - Marileen Dogterom
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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14
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Ivashko-Pachima Y, Sayas CL, Malishkevich A, Gozes I. ADNP/NAP dramatically increase microtubule end-binding protein-Tau interaction: a novel avenue for protection against tauopathy. Mol Psychiatry 2017; 22:1335-1344. [PMID: 28115743 DOI: 10.1038/mp.2016.255] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/20/2016] [Accepted: 12/06/2016] [Indexed: 12/30/2022]
Abstract
Activity-dependent neuroprotective protein (ADNP), vital for brain formation and cognitive function, is mutated in autism and linked to neurodegenerative/psychiatric diseases. An eight-amino-acid peptide snippet of ADNP, NAP (NAPVSIPQ), identified as a smallest active fragment, includes the SxIP microtubule (MT) end-binding protein (EB) association motif, and enhances ADNP-EB3 interaction. Depletion of EB1 or EB3 abolishes NAP protection against zinc intoxication. Furthermore, NAP enhances Tau-MT interaction, and Tau regulates the localization and function of EB1 and EB3 in developing neuronal cells. Here, we asked how NAP (ADNP) enhances Tau-MT interactions and whether this is mediated by EBs. We showed, for we believe the first time, that NAP augmented endogenous EB1 comet density in the N1E-115 neuroblastoma neuronal model. This finding was substantiated by cell transfection with fluorescent EB1 and live cell imaging. NAP increased comet amounts, length and speed. At the molecular level, NAP enhanced EB3 homodimer formation, while decreasing EB1-EB3 heterodimer content and driving EB1- and EB3-Tau interactions (dramatic 20-fold increases), leading to recruitment of EB1/EB3 and Tau to MTs under zinc intoxication. Our previous results showed that while NAP protected neuronal-like cells against oxidative stress, it did not protect NIH3T3 fibroblasts. Here, NAP did not protect NIH3T3 cells against zinc intoxication, unless these cells were transfected with Tau. Interestingly, other MT associated proteins (MAPs) may replace Tau, thus, EB-Tau (MAPs) interaction is identified as a novel target for endogenous ADNP neuroprotection, and a future target for drug development, with NAP as a prototype.
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Affiliation(s)
- Y Ivashko-Pachima
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors, Dr. Diana and Zelman Elton (Elbaum) Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - C Laura Sayas
- Centre for Biomedical Research of the Canary Islands (CIBICAN), Institute for Biomedical Technologies (ITB), University of La Laguna (ULL), Tenerife, Spain
| | - A Malishkevich
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors, Dr. Diana and Zelman Elton (Elbaum) Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
| | - I Gozes
- The Lily and Avraham Gildor Chair for the Investigation of Growth Factors, Dr. Diana and Zelman Elton (Elbaum) Laboratory for Molecular Neuroendocrinology, Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Sagol School of Neuroscience and Adams Super Center for Brain Studies, Tel Aviv University, Tel Aviv, Israel
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15
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Mustyatsa VV, Boyakhchyan AV, Ataullakhanov FI, Gudimchuk NB. EB-family proteins: Functions and microtubule interaction mechanisms. BIOCHEMISTRY (MOSCOW) 2017; 82:791-802. [DOI: 10.1134/s0006297917070045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Nehlig A, Molina A, Rodrigues-Ferreira S, Honoré S, Nahmias C. Regulation of end-binding protein EB1 in the control of microtubule dynamics. Cell Mol Life Sci 2017; 74:2381-2393. [PMID: 28204846 PMCID: PMC11107513 DOI: 10.1007/s00018-017-2476-2] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 01/13/2017] [Accepted: 01/24/2017] [Indexed: 12/14/2022]
Abstract
The regulation of microtubule dynamics is critical to ensure essential cell functions, such as proper segregation of chromosomes during mitosis or cell polarity and migration. End-binding protein 1 (EB1) is a plus-end-tracking protein (+TIP) that accumulates at growing microtubule ends and plays a pivotal role in the regulation of microtubule dynamics. EB1 autonomously binds an extended tubulin-GTP/GDP-Pi structure at growing microtubule ends and acts as a molecular scaffold that recruits a large number of regulatory +TIPs through interaction with CAP-Gly or SxIP motifs. While extensive studies have focused on the structure of EB1-interacting site at microtubule ends and its role as a molecular platform, the mechanisms involved in the negative regulation of EB1 have only started to emerge and remain poorly understood. In this review, we summarize recent studies showing that EB1 association with MT ends is regulated by post-translational modifications and affected by microtubule-targeting agents. We also present recent findings that structural MAPs, that have no tip-tracking activity, physically interact with EB1 to prevent its accumulation at microtubule plus ends. These observations point out a novel concept of "endogenous EB1 antagonists" and emphasize the importance of finely regulating EB1 function at growing microtubule ends.
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Affiliation(s)
- Anne Nehlig
- Inserm U981, Institut Gustave Roussy, 114 rue Edouard Vaillant, 94800, Villejuif, France
- University Paris Saclay, 94800, Villejuif, France
| | - Angie Molina
- Inserm U981, Institut Gustave Roussy, 114 rue Edouard Vaillant, 94800, Villejuif, France
- University Paris Saclay, 94800, Villejuif, France
- CBD, University of Toulouse-3, Toulouse, France
| | - Sylvie Rodrigues-Ferreira
- Inserm U981, Institut Gustave Roussy, 114 rue Edouard Vaillant, 94800, Villejuif, France
- University Paris Saclay, 94800, Villejuif, France
| | - Stéphane Honoré
- Aix Marseille University, Inserm U-911, CRO2, Marseille, France
- Service Pharmacie, CHU Hôpital de La Timone, APHM, Marseille, France
| | - Clara Nahmias
- Inserm U981, Institut Gustave Roussy, 114 rue Edouard Vaillant, 94800, Villejuif, France.
- University Paris Saclay, 94800, Villejuif, France.
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17
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Fong KW, Au FKC, Jia Y, Yang S, Zhou L, Qi RZ. Microtubule plus-end tracking of end-binding protein 1 (EB1) is regulated by CDK5 regulatory subunit-associated protein 2. J Biol Chem 2017; 292:7675-7687. [PMID: 28320860 DOI: 10.1074/jbc.m116.759746] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 03/15/2017] [Indexed: 01/08/2023] Open
Abstract
Microtubules are polar cytoskeleton filaments that extend via growth at their plus ends. Microtubule plus-end-tracking proteins (+TIPs) accumulate at these growing plus ends to control microtubule dynamics and attachment. The +TIP end-binding protein 1 (EB1) and its homologs possess an autonomous plus-end-tracking mechanism and interact with other known +TIPs, which then recruit those +TIPs to the growing plus ends. A major +TIP class contains the SXIP (Ser-X-Ile-Pro, with X denoting any amino acid residue) motif, known to interact with EB1 and its homologs for plus-end tracking, but the role of SXIP in regulating EB1 activities is unclear. We show here that an interaction of EB1 with the SXIP-containing +TIP CDK5 regulatory subunit-associated protein 2 (CDK5RAP2) regulates several EB1 activities, including microtubule plus-end tracking, dynamics at microtubule plus ends, microtubule and α/β-tubulin binding, and microtubule polymerization. The SXIP motif fused with a dimerization domain from CDK5RAP2 significantly enhanced EB1 plus-end-tracking and microtubule-polymerizing and bundling activities, but the SXIP motif alone failed to do so. An SXIP-binding-deficient EB1 mutant displayed significantly lower microtubule plus-end tracking than the wild-type protein in transfected cells. These results suggest that EB1 cooperates with CDK5RAP2 and perhaps other SXIP-containing +TIPs in tracking growing microtubule tips. We also generated plus-end-tracking chimeras of CDK5RAP2 and the adenomatous polyposis coli protein (APC) and found that overexpression of the dimerization domains interfered with microtubule plus-end tracking of their respective SXIP-containing chimeras. Our results suggest that disruption of SXIP dimerization enables detailed investigations of microtubule plus-end-associated functions of individual SXIP-containing +TIPs.
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Affiliation(s)
- Ka-Wing Fong
- From the Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Franco K C Au
- From the Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yue Jia
- From the Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Shaozhong Yang
- From the Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Liying Zhou
- From the Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Robert Z Qi
- From the Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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18
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Manatschal C, Farcas AM, Degen MS, Bayer M, Kumar A, Landgraf C, Volkmer R, Barral Y, Steinmetz MO. Molecular basis of Kar9-Bim1 complex function during mating and spindle positioning. Mol Biol Cell 2016; 27:mbc.E16-07-0552. [PMID: 27682587 PMCID: PMC5170556 DOI: 10.1091/mbc.e16-07-0552] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 11/17/2022] Open
Abstract
The Kar9 pathway promotes nuclear fusion during mating and spindle alignment during metaphase in budding yeast. How Kar9 supports the different outcome of these two divergent processes is an open question. Here, we show that three sites in the C-terminal disordered domain of Kar9 mediate tight Kar9 interaction with the C-terminal dimerization domain of Bim1 (EB1 orthologue). Site1 and Site2 contain SxIP motifs; however, Site3 defines a novel type of EB1-binding site. Whereas Site2 and Site3 mediate Kar9 recruitment to microtubule tips, nuclear movement and karyogamy, solely Site2 functions in spindle positioning during metaphase. Site1 in turn plays an inhibitory role during mating. Additionally, the Kar9-Bim1 complex is involved in microtubule-independent activities during mating. Together, our data reveal how multiple and partially redundant EB1-binding sites provide a microtubule-associated protein with the means to modulate its biochemical properties to promote different molecular processes during cell proliferation and differentiation.
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Affiliation(s)
- Cristina Manatschal
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Ana-Maria Farcas
- Institute of Biochemistry, Biology Department, ETH Zürich, Zürich, Switzerland
| | - Miriam Steiner Degen
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Mathias Bayer
- Institute of Biochemistry, Biology Department, ETH Zürich, Zürich, Switzerland
| | - Anil Kumar
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Christiane Landgraf
- Institut für Medizinische Immunologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Rudolf Volkmer
- Institut für Medizinische Immunologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Yves Barral
- Institute of Biochemistry, Biology Department, ETH Zürich, Zürich, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
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19
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Albracht CD, Guzik-Lendrum S, Rayment I, Gilbert SP. Heterodimerization of Kinesin-2 KIF3AB Modulates Entry into the Processive Run. J Biol Chem 2016; 291:23248-23256. [PMID: 27637334 DOI: 10.1074/jbc.m116.752196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Indexed: 11/06/2022] Open
Abstract
Mammalian KIF3AB is an N-terminal processive kinesin-2 that is best known for its roles in intracellular transport. There has been significant interest in KIF3AB to define the key principles that underlie its processivity but also to define the mechanistic basis of its sensitivity to force. In this study, the kinetics for entry into the processive run were quantified. The results show for KIF3AB that the kinetics of microtubule association at 7 μm-1 s-1 is less than the rates observed for KIF3AA at 13 μm-1 s-1 or KIF3BB at 11.9 μm-1 s-1 ADP release after microtubule association for KIF3AB is 33 s-1 and is significantly slower than ADP release from homodimeric KIF3AA and KIF3BB, which reach 80-90 s-1 To explore the interhead communication implied by the rate differences at these first steps, we compared the kinetics of KIF3AB microtubule association followed by ADP release with the kinetics for mixtures of KIF3AA plus KIF3BB. Surprisingly, the kinetics of KIF3AB are not equivalent to any of the mixtures of KIF3AA + KIF3BB. In fact, the transients for each of the mixtures overlay the transients for KIF3AA and KIF3BB. These results reveal that intermolecular communication within the KIF3AB heterodimer modulates entry into the processive run, and the results suggest that it is the high rate of microtubule association that drives rebinding to the microtubule after force-dependent motor detachment.
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Affiliation(s)
- Clayton D Albracht
- From the Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180 and
| | - Stephanie Guzik-Lendrum
- From the Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180 and
| | - Ivan Rayment
- the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Susan P Gilbert
- From the Department of Biological Sciences and the Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180 and
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20
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Guzik-Lendrum S, Rank KC, Bensel BM, Taylor KC, Rayment I, Gilbert SP. Kinesin-2 KIF3AC and KIF3AB Can Drive Long-Range Transport along Microtubules. Biophys J 2016; 109:1472-82. [PMID: 26445448 DOI: 10.1016/j.bpj.2015.08.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/03/2015] [Accepted: 08/04/2015] [Indexed: 12/14/2022] Open
Abstract
Mammalian KIF3AC is classified as a heterotrimeric kinesin-2 that is best known for organelle transport in neurons, yet in vitro studies to characterize its single molecule behavior are lacking. The results presented show that a KIF3AC motor that includes the native helix α7 sequence for coiled-coil formation is highly processive with run lengths of ∼1.23 μm and matching those exhibited by conventional kinesin-1. This result was unexpected because KIF3AC exhibits the canonical kinesin-2 neck-linker sequence that has been reported to be responsible for shorter run lengths observed for another heterotrimeric kinesin-2, KIF3AB. However, KIF3AB with its native neck linker and helix α7 is also highly processive with run lengths of ∼1.62 μm and exceeding those of KIF3AC and kinesin-1. Loop L11, a component of the microtubule-motor interface and implicated in activating ADP release upon microtubule collision, is significantly extended in KIF3C as compared with other kinesins. A KIF3AC encoding a truncation in KIF3C loop L11 (KIF3ACΔL11) exhibited longer run lengths at ∼1.55 μm than wild-type KIF3AC and were more similar to KIF3AB run lengths, suggesting that L11 also contributes to tuning motor processivity. The steady-state ATPase results show that shortening L11 does not alter kcat, consistent with the observation that single molecule velocities are not affected by this truncation. However, shortening loop L11 of KIF3C significantly increases the microtubule affinity of KIF3ACΔL11, revealing another structural and mechanistic property that can modulate processivity. The results presented provide new, to our knowledge, insights to understand structure-function relationships governing processivity and a better understanding of the potential of KIF3AC for long-distance transport in neurons.
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Affiliation(s)
- Stephanie Guzik-Lendrum
- Department of Biological Sciences and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
| | - Katherine C Rank
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin
| | - Brandon M Bensel
- Department of Biological Sciences and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
| | - Keenan C Taylor
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin
| | - Ivan Rayment
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin.
| | - Susan P Gilbert
- Department of Biological Sciences and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York.
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21
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Structural basis for misregulation of kinesin KIF21A autoinhibition by CFEOM1 disease mutations. Sci Rep 2016; 6:30668. [PMID: 27485312 PMCID: PMC4971492 DOI: 10.1038/srep30668] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 07/08/2016] [Indexed: 11/09/2022] Open
Abstract
Tight regulation of kinesin activity is crucial and malfunction is linked to neurological diseases. Point mutations in the KIF21A gene cause congenital fibrosis of the extraocular muscles type 1 (CFEOM1) by disrupting the autoinhibitory interaction between the motor domain and a regulatory region in the stalk. However, the molecular mechanism underlying the misregulation of KIF21A activity in CFEOM1 is not understood. Here, we show that the KIF21A regulatory domain containing all disease-associated substitutions in the stalk forms an intramolecular antiparallel coiled coil that inhibits the kinesin. CFEOM1 mutations lead to KIF21A hyperactivation by affecting either the structural integrity of the antiparallel coiled coil or the autoinhibitory binding interface, thereby reducing its affinity for the motor domain. Interaction of the KIF21A regulatory domain with the KIF21B motor domain and sequence similarities to KIF7 and KIF27 strongly suggest a conservation of this regulatory mechanism in other kinesin-4 family members.
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22
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Thomas GE, Bandopadhyay K, Sutradhar S, Renjith MR, Singh P, Gireesh KK, Simon S, Badarudeen B, Gupta H, Banerjee M, Paul R, Mitra J, Manna TK. EB1 regulates attachment of Ska1 with microtubules by forming extended structures on the microtubule lattice. Nat Commun 2016; 7:11665. [PMID: 27225956 PMCID: PMC4894954 DOI: 10.1038/ncomms11665] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/18/2016] [Indexed: 12/22/2022] Open
Abstract
Kinetochore couples chromosome movement to dynamic microtubules, a process that is fundamental to mitosis in all eukaryotes but poorly understood. In vertebrates, spindle-kinetochore-associated (Ska1–3) protein complex plays an important role in this process. However, the proteins that stabilize Ska-mediated kinetochore-microtubule attachment remain unknown. Here we show that microtubule plus-end tracking protein EB1 facilitates Ska localization on microtubules in vertebrate cells. EB1 depletion results in a significant reduction of Ska1 recruitment onto microtubules and defects in mitotic chromosome alignment, which is also reflected in computational modelling. Biochemical experiments reveal that EB1 interacts with Ska1, facilitates Ska1-microtubule attachment and together stabilizes microtubules. Structural studies reveal that EB1 either with Ska1 or Ska complex forms extended structures on microtubule lattice. Results indicate that EB1 promotes Ska association with K-fibres and facilitates kinetochore-microtubule attachment. They also implicate that in vertebrates, chromosome coupling to dynamic microtubules could be mediated through EB1-Ska extended structures. Ska1 is a kinetochore-localised protein that couples kinetochore movement to microtubule (MT) depolymerisation. Here Thomas et al. show that the MT +TIP binding protein EB1 recruits Ska1 to the MT-kinetochore interface and stabilises the interaction between Ska1 and MTs.
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Affiliation(s)
- Geethu E Thomas
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - K Bandopadhyay
- School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Sabyasachi Sutradhar
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - M R Renjith
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Puja Singh
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - K K Gireesh
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Steny Simon
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Binshad Badarudeen
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Hindol Gupta
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Manidipa Banerjee
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Raja Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - J Mitra
- School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
| | - Tapas K Manna
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, CET Campus, Thiruvananthapuram 695016, India
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23
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Lopez BJ, Valentine MT. The +TIP coordinating protein EB1 is highly dynamic and diffusive on microtubules, sensitive to GTP analog, ionic strength, and EB1 concentration. Cytoskeleton (Hoboken) 2016; 73:23-34. [PMID: 26663881 DOI: 10.1002/cm.21267] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 12/04/2015] [Accepted: 12/04/2015] [Indexed: 01/06/2023]
Abstract
Using single-molecule fluorescence microscopy, we investigated the dynamics of dye-labeled EB1, a +TIP microtubule binding protein. To promote EB1 binding along the entire microtubule length, we formed microtubules using the nonhydrolyzable GTP analogs GMPCPP and GTPγS. Through precise tracking of the motions of individual dye-labeled proteins, we found EB1 to be highly dynamic and continuously diffusive while bound to a microtubule, with a diffusion coefficient and characteristic binding lifetime that were sensitive to both the choice of GTP analog and the buffer ionic strength. Using fluorescence-based equilibrium binding measurements, we found EB1 binding to be cooperative and also sensitive to GTP analog and ionic strength. By tracking the motion of a small number of individually-labeled EB1 proteins within a bath of unlabeled EB1 proteins, we determined the effects of increasing the total EB1 concentration on binding and dynamics. We found that the diffusion coefficient decreased with increasing EB1 concentration, which may be due at least in part, to the cooperativity of EB1 binding. Our results may have important consequences for the assembly and organization of the growing microtubule plus-end.
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Affiliation(s)
- Benjamin J Lopez
- Department of Mechanical Engineering and the Neuroscience Research Institute, University of California, Santa Barbara, California
| | - Megan T Valentine
- Department of Mechanical Engineering and the Neuroscience Research Institute, University of California, Santa Barbara, California
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24
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Tang EI, Mruk DD, Cheng CY. Regulation of microtubule (MT)-based cytoskeleton in the seminiferous epithelium during spermatogenesis. Semin Cell Dev Biol 2016; 59:35-45. [PMID: 26791048 DOI: 10.1016/j.semcdb.2016.01.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 01/05/2016] [Indexed: 12/31/2022]
Abstract
In rodents and humans, testicular cells, similar to other mammalian cells, are supported by actin-, microtubule (MT)- and intermediate filament-based cytoskeletons. Although the cytoskeletal network of the testis serves an important role in regulating spermatogenesis during the epithelial cycle, most of the published findings in the literature are limited to studies that only visualize these cytoskeletons in the seminiferous epithelium. Few focus on the underlying molecular mechanism that regulates their organization in the epithelium in response to changes in the stages of the epithelial cycle. Functional studies in the last decade have begun to focus on the role of binding proteins that regulate these cytoskeletons, with some interesting findings rapidly emerging in the field. Since the actin- and intermediate filament-based cytoskeletons have been recently reviewed, herein we focus on the MT-based cytoskeleton for two reasons. First, besides serving as a structural support cytoskeleton, MTs are known to serve as the track to support and facilitate the transport of germ cells, such as preleptotene spermatocytes connected in clones and elongating/elongated spermatids during spermiogenesis, across the blood-testis barrier (BTB) and the adluminal compartment, respectively, during spermatogenesis. While these cellular events are crucial to the completion of spermatogenesis, they have been largely ignored in the past. Second, MT-based cytoskeleton is working in concert with the actin-based cytoskeleton to provide structural support for the transport of intracellular organelles across the cell cytosol, such as endosome-based vesicles, and phagosomes, which contain residual bodies detached from spermatids, to maintain the cellular homeostasis in the seminiferous epithelium. We critically evaluate some recent published findings herein to support a hypothesis regarding the role of MT in conferring germ cell transport in the seminiferous epithelium.
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Affiliation(s)
- Elizabeth I Tang
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, NY 10065, United States
| | - Dolores D Mruk
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, NY 10065, United States
| | - C Yan Cheng
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, NY 10065, United States.
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25
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Harris JA, Liu Y, Yang P, Kner P, Lechtreck KF. Single-particle imaging reveals intraflagellar transport-independent transport and accumulation of EB1 in Chlamydomonas flagella. Mol Biol Cell 2015; 27:295-307. [PMID: 26631555 PMCID: PMC4713132 DOI: 10.1091/mbc.e15-08-0608] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/20/2015] [Indexed: 12/20/2022] Open
Abstract
The microtubule (MT) plus-end tracking protein EB1 is present at the tips of cilia and flagella; end-binding protein 1 (EB1) remains at the tip during flagellar shortening and in the absence of intraflagellar transport (IFT), the predominant protein transport system in flagella. To investigate how EB1 accumulates at the flagellar tip, we used in vivo imaging of fluorescent protein-tagged EB1 (EB1-FP) in Chlamydomonas reinhardtii. After photobleaching, the EB1 signal at the flagellar tip recovered within minutes, indicating an exchange with unbleached EB1 entering the flagella from the cell body. EB1 moved independent of IFT trains, and EB1-FP recovery did not require the IFT pathway. Single-particle imaging showed that EB1-FP is highly mobile along the flagellar shaft and displays a markedly reduced mobility near the flagellar tip. Individual EB1-FP particles dwelled for several seconds near the flagellar tip, suggesting the presence of stable EB1 binding sites. In simulations, the two distinct phases of EB1 mobility are sufficient to explain its accumulation at the tip. We propose that proteins uniformly distributed throughout the cytoplasm like EB1 accumulate locally by diffusion and capture; IFT, in contrast, might be required to transport proteins against cellular concentration gradients into or out of cilia.
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Affiliation(s)
- J Aaron Harris
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Yi Liu
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233
| | - Peter Kner
- College of Engineering, University of Georgia, Athens, GA 30602
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
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26
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ADNP/ADNP2 expression in oligodendrocytes: implication for myelin-related neurodevelopment. J Mol Neurosci 2015; 57:304-13. [DOI: 10.1007/s12031-015-0640-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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27
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Chen J, Luo Y, Li L, Ran J, Wang X, Gao S, Liu M, Li D, Shui W, Zhou J. Phosphoregulation of the dimerization and functions of end-binding protein 1. Protein Cell 2015; 5:795-9. [PMID: 25048701 PMCID: PMC4180461 DOI: 10.1007/s13238-014-0081-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Jie Chen
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Youguang Luo
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Lixin Li
- High-Throughput Molecular Drug Discovery Center, Tianjin Joint Academy of Biotechnology and Medicine, Tianjin, 300457 China
| | - Jie Ran
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Xincheng Wang
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Siqi Gao
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Min Liu
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Dengwen Li
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
| | - Wenqing Shui
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
- High-Throughput Molecular Drug Discovery Center, Tianjin Joint Academy of Biotechnology and Medicine, Tianjin, 300457 China
| | - Jun Zhou
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071 China
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28
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The NAP motif of activity-dependent neuroprotective protein (ADNP) regulates dendritic spines through microtubule end binding proteins. Mol Psychiatry 2014; 19:1115-24. [PMID: 25178163 DOI: 10.1038/mp.2014.97] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 06/14/2014] [Accepted: 07/08/2014] [Indexed: 12/29/2022]
Abstract
The NAP motif of activity-dependent neuroprotective protein (ADNP) enhanced memory scores in patients suffering from mild cognitive impairment and protected activities of daily living in schizophrenia patients, while fortifying microtubule (MT)-dependent axonal transport, in mice and flies. The question is how does NAP fortify MTs? Our sequence analysis identified the MT end-binding protein (EB1)-interacting motif SxIP (SIP, Ser-Ile-Pro) in ADNP/NAP and showed specific SxIP binding sites in all members of the EB protein family (EB1-3). Others found that EB1 enhancement of neurite outgrowth is attenuated by EB2, while EB3 interacts with postsynaptic density protein 95 (PSD-95) to modulate dendritic plasticity. Here, NAP increased PSD-95 expression in dendritic spines, which was inhibited by EB3 silencing. EB1 or EB3, but not EB2 silencing inhibited NAP-mediated cell protection, which reflected NAP binding specificity. NAPVSKIPQ (SxIP=SKIP), but not NAPVAAAAQ mimicked NAP activity. ADNP, essential for neuronal differentiation and brain formation in mouse, a member of the SWI/SNF chromatin remodeling complex and a major protein mutated in autism and deregulated in schizophrenia in men, showed similar EB interactions, which were enhanced by NAP treatment. The newly identified shared MT target of NAP/ADNP is directly implicated in synaptic plasticity, explaining the breadth and efficiency of neuroprotective/neurotrophic capacities.
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Gireesh KK, Sreeja JS, Chakraborti S, Singh P, Thomas GE, Gupta H, Manna T. Microtubule +TIP protein EB1 binds to GTP and undergoes dissociation from dimer to monomer on binding GTP. Biochemistry 2014; 53:5551-7. [PMID: 25111064 DOI: 10.1021/bi5007942] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The +TIP protein EB1 autonomously tracks the growing plus end of microtubules and regulates plus-end dynamics. Previous studies have indicated that EB1 can recognize GTP-bound tubulin structures at the plus end, and it localizes on the microtubule surface at a site close to the exchangeable GTP-binding site of tubulin. Although the GTP-dependent structural change in tubulin has been demonstrated to be a critical determinant for recognition of plus ends by EB1, the effect of GTP on the structure of EB1 has remained unclear. Here, we have used spectroscopic, calorimetric, and biochemical methods to analyze the effect of GTP on EB1 in vitro. Isothermal titration calorimetry and tryptophan fluorescence quenching experiments demonstrated that EB1 binds to GTP with a dissociation constant ~30 μM. Circular dichroism measurements showed that EB1 undergoes changes in its secondary structure on binding GTP. Size-exclusion chromatography and urea-induced unfolding analyses revealed that GTP binding induces dissociation of the EB1 dimer to monomers. Size-exclusion chromatography followed by biochemical analysis further determined that EB1-GTP binding involves association of approximately one molecule of GTP per EB1 monomer. The results reveal a hitherto unknown GTP-dependent mechanism of dimer-to-monomer transition in EB1 and further implicate its possible role in regulating the stability of the EB1 dimer vs monomer as well as plus-end regulation in cells.
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Affiliation(s)
- K K Gireesh
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram , CET Campus, Thiruvananthapuram, Kerala 695016, India
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