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Kanaba T, Maesaki R, Mori T, Ito Y, Hakoshima T, Mishima M. Microtubule-binding sites of the CH domain of EB1 and its autoinhibition revealed by NMR. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:499-507. [PMID: 23128140 DOI: 10.1016/j.bbapap.2012.10.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 10/10/2012] [Accepted: 10/26/2012] [Indexed: 12/20/2022]
Abstract
End-binding protein 1 (EB1) is one of the best studied plus-end tracking proteins. It is known that EB1 specifically binds the plus ends of microtubules (MTs) and promotes MT growth. EB1 activity is thought to be autoinhibited by an intramolecular interaction. Recent cryo-EM analyses showed that the CH domain of Mal3p (Schizosaccharomyces pombe EB1 homolog) binds to GMPCPP-MT (Sandblad, L. Cell 127 (2006) 1415-24), and strongly binds GTPγS-MT which is proposed to mimic MT plus ends better than GMPCPP-MT (Maurer S.P. et al. Cell 149 (2012) 371-82). Here, we report on the MT binding sites of the CH domain of EB1 as revealed by NMR using the transferred cross-saturation method. In this study, we used GMPCPP-MT and found that the MT binding sites are very similar to the binding site for GTPγS-MT as suggested by cryo-EM (Maurer S.P. et al. Cell 149 (2012) 371-82). Notably, the N-terminal tip of helix α6 of the CH domain did not make contact with GMPCPP-MT, in contrast to the cryo-EM study which showed that it is closely located to a putative switch region of β-tubulin in GTPγS-MT (Maurer S.P. et al. Cell 149 (2012) 371-82). Further, we found that the intramolecular interaction site of EB1 overlaps the MT binding sites, indicating that the MT binding sites are masked by interaction with the C-terminal domain. We propose a structural view of autoinhibition and its release mechanism through competition binding with binding partners such as adenomatous polyposis coli protein.
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Affiliation(s)
- Teppei Kanaba
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan
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52
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EB1 acetylation by P300/CBP-associated factor (PCAF) ensures accurate kinetochore-microtubule interactions in mitosis. Proc Natl Acad Sci U S A 2012; 109:16564-9. [PMID: 23001180 DOI: 10.1073/pnas.1202639109] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In eukaryotes, microtubules are essential for cellular plasticity and dynamics. Here we show that P300/CBP-associated factor (PCAF), a kinetochore-associated acetyltransferase, acts as a negative modulator of microtubule stability through acetylation of EB1, a protein that controls the plus ends of microtubules. PCAF acetylates EB1 on K220 and disrupts the stability of a hydrophobic cavity on the dimerized EB1 C terminus, which was previously reported to interact with plus-end tracking proteins (TIPs) containing the SxIP motif. As determined with an EB1 acetyl-K220-specific antibody, K220 acetylation is dramatically increased in mitosis and localized to the spindle microtubule plus ends. Surprisingly, persistent acetylation of EB1 delays metaphase alignment, resulting in impaired checkpoint silencing. Consequently, suppression of Mad2 overrides mitotic arrest induced by persistent EB1 acetylation. Thus, our findings identify dynamic acetylation of EB1 as a molecular mechanism to orchestrate accurate kinetochore-microtubule interactions in mitosis. These results establish a previously uncharacterized regulatory mechanism governing localization of microtubule plus-end tracking proteins and thereby the plasticity and dynamics of cells.
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53
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Seetapun D, Castle BT, McIntyre AJ, Tran PT, Odde DJ. Estimating the microtubule GTP cap size in vivo. Curr Biol 2012; 22:1681-7. [PMID: 22902755 DOI: 10.1016/j.cub.2012.06.068] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/14/2012] [Accepted: 06/27/2012] [Indexed: 12/18/2022]
Abstract
Microtubules (MTs) polymerize via net addition of GTP-tubulin subunits to the MT plus end, which subsequently hydrolyze to GDP-tubulin in the MT lattice. Relatively stable GTP-tubulin subunits create a "GTP cap" at the growing MT plus end that suppresses catastrophe. To understand MT assembly regulation, we need to understand GTP hydrolysis reaction kinetics and the GTP cap size. In vitro, the GTP cap has been estimated to be as small as one layer (13 subunits) or as large as 100-200 subunits. GTP cap size estimates in vivo have not yet been reported. Using EB1-EGFP as a marker for GTP-tubulin in epithelial cells, we find on average (1) 270 EB1 dimers bound to growing MT plus ends, and (2) a GTP cap size of ∼750 tubulin subunits. Thus, in vivo, the GTP cap is far larger than previous estimates in vitro, and ∼60-fold larger than a single layer cap. We also find that the tail of a large GTP cap promotes MT rescue and suppresses shortening. We speculate that a large GTP cap provides a locally concentrated scaffold for tip-tracking proteins and confers persistence to assembly in the face of physical barriers such as the cell cortex.
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Affiliation(s)
- Dominique Seetapun
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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54
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Evolution of the eukaryotic dynactin complex, the activator of cytoplasmic dynein. BMC Evol Biol 2012; 12:95. [PMID: 22726940 PMCID: PMC3583065 DOI: 10.1186/1471-2148-12-95] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 06/22/2012] [Indexed: 12/03/2022] Open
Abstract
Background Dynactin is a large multisubunit protein complex that enhances the processivity of cytoplasmic dynein and acts as an adapter between dynein and the cargo. It is composed of eleven different polypeptides of which eight are unique to this complex, namely dynactin1 (p150Glued), dynactin2 (p50 or dynamitin), dynactin3 (p24), dynactin4 (p62), dynactin5 (p25), dynactin6 (p27), and the actin-related proteins Arp1 and Arp10 (Arp11). Results To reveal the evolution of dynactin across the eukaryotic tree the presence or absence of all dynactin subunits was determined in most of the available eukaryotic genome assemblies. Altogether, 3061 dynactin sequences from 478 organisms have been annotated. Phylogenetic trees of the various subunit sequences were used to reveal sub-family relationships and to reconstruct gene duplication events. Especially in the metazoan lineage, several of the dynactin subunits were duplicated independently in different branches. The largest subunit repertoire is found in vertebrates. Dynactin diversity in vertebrates is further increased by alternative splicing of several subunits. The most prominent example is the dynactin1 gene, which may code for up to 36 different isoforms due to three different transcription start sites and four exons that are spliced as differentially included exons. Conclusions The dynactin complex is a very ancient complex that most likely included all subunits in the last common ancestor of extant eukaryotes. The absence of dynactin in certain species coincides with that of the cytoplasmic dynein heavy chain: Organisms that do not encode cytoplasmic dynein like plants and diplomonads also do not encode the unique dynactin subunits. The conserved core of dynactin consists of dynactin1, dynactin2, dynactin4, dynactin5, Arp1, and the heterodimeric actin capping protein. The evolution of the remaining subunits dynactin3, dynactin6, and Arp10 is characterized by many branch- and species-specific gene loss events.
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55
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Abstract
Dynactin is a required cofactor for the minus-end-directed microtubule motor cytoplasmic dynein. Mutations within the highly conserved CAP-Gly domain of dynactin cause neurodegenerative disease. Here, we show that the CAP-Gly domain is necessary to enrich dynactin at the distal end of primary neurons. While the CAP-Gly domain is not required for sustained transport along the axon, we find that the distal accumulation facilitates the efficient initiation of retrograde vesicular transport from the neurite tip. Neurodegenerative disease mutations in the CAP-Gly domain prevent the distal enrichment of dynactin thereby inhibiting the initiation of retrograde transport. Thus, we propose a model in which distal dynactin is a key mediator in promoting the interaction among the microtubule, dynein motor, and cargo for the efficient initiation of transport. Mutations in the CAP-Gly domain disrupt the formation of the motor-cargo complex, highlighting the specific defects in axonal transport that may lead to neurodegeneration.
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Affiliation(s)
- Armen J. Moughamian
- Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, D400 Richards Building, 3700 Hamilton Walk, Philadelphia, Pennsylvania 19104-6085, USA
| | - Erika L.F. Holzbaur
- Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, D400 Richards Building, 3700 Hamilton Walk, Philadelphia, Pennsylvania 19104-6085, USA
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56
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Maurer S, Fourniol F, Bohner G, Moores C, Surrey T. EBs recognize a nucleotide-dependent structural cap at growing microtubule ends. Cell 2012; 149:371-82. [PMID: 22500803 PMCID: PMC3368265 DOI: 10.1016/j.cell.2012.02.049] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 12/19/2011] [Accepted: 02/10/2012] [Indexed: 11/24/2022]
Abstract
Growing microtubule ends serve as transient binding platforms for essential proteins that regulate microtubule dynamics and their interactions with cellular substructures. End-binding proteins (EBs) autonomously recognize an extended region at growing microtubule ends with unknown structural characteristics and then recruit other factors to the dynamic end structure. Using cryo-electron microscopy, subnanometer single-particle reconstruction, and fluorescence imaging, we present a pseudoatomic model of how the calponin homology (CH) domain of the fission yeast EB Mal3 binds to the end regions of growing microtubules. The Mal3 CH domain bridges protofilaments except at the microtubule seam. By binding close to the exchangeable GTP-binding site, the CH domain is ideally positioned to sense the microtubule's nucleotide state. The same microtubule-end region is also a stabilizing structural cap protecting the microtubule from depolymerization. This insight supports a common structural link between two important biological phenomena, microtubule dynamic instability and end tracking.
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Affiliation(s)
- Sebastian P. Maurer
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Franck J. Fourniol
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Gergő Bohner
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Carolyn A. Moores
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Thomas Surrey
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
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57
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58
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Iimori M, Ozaki K, Chikashige Y, Habu T, Hiraoka Y, Maki T, Hayashi I, Obuse C, Matsumoto T. A mutation of the fission yeast EB1 overcomes negative regulation by phosphorylation and stabilizes microtubules. Exp Cell Res 2012; 318:262-75. [DOI: 10.1016/j.yexcr.2011.11.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 10/05/2011] [Accepted: 11/09/2011] [Indexed: 11/16/2022]
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59
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Stringham EG, Marcus-Gueret N, Ramsay L, Schmidt KL. Live Cell Imaging of the Cytoskeleton. Methods Enzymol 2012; 505:203-17. [DOI: 10.1016/b978-0-12-388448-0.00019-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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60
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Brüning-Richardson A, Langford KJ, Ruane P, Lee T, Askham JM, Morrison EE. EB1 is required for spindle symmetry in mammalian mitosis. PLoS One 2011; 6:e28884. [PMID: 22216133 PMCID: PMC3244432 DOI: 10.1371/journal.pone.0028884] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 11/16/2011] [Indexed: 12/30/2022] Open
Abstract
Most information about the roles of the adenomatous polyposis coli protein (APC) and its binding partner EB1 in mitotic cells has come from siRNA studies. These suggest functions in chromosomal segregation and spindle positioning whose loss might contribute to tumourigenesis in cancers initiated by APC mutation. However, siRNA-based approaches have drawbacks associated with the time taken to achieve significant expression knockdown and the pleiotropic effects of EB1 and APC gene knockdown. Here we describe the effects of microinjecting APC- or EB1- specific monoclonal antibodies and a dominant-negative EB1 protein fragment into mammalian mitotic cells. The phenotypes observed were consistent with the roles proposed for EB1 and APC in chromosomal segregation in previous work. However, EB1 antibody injection also revealed two novel mitotic phenotypes, anaphase-specific cortical blebbing and asymmetric spindle pole movement. The daughters of microinjected cells displayed inequalities in microtubule content, with the greatest differences seen in the products of mitoses that showed the severest asymmetry in spindle pole movement. Daughters that inherited the least mobile pole contained the fewest microtubules, consistent with a role for EB1 in processes that promote equality of astral microtubule function at both poles in a spindle. We propose that these novel phenotypes represent APC-independent roles for EB1 in spindle pole function and the regulation of cortical contractility in the later stages of mitosis. Our work confirms that EB1 and APC have important mitotic roles, the loss of which could contribute to CIN in colorectal tumour cells.
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Affiliation(s)
- Anke Brüning-Richardson
- Leeds Institute of Molecular Medicine, University of Leeds, St. James's University Hospital, Leeds, United Kingdom.
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61
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Yao X, Zhang J, Zhou H, Wang E, Xiang X. In vivo roles of the basic domain of dynactin p150 in microtubule plus-end tracking and dynein function. Traffic 2011; 13:375-87. [PMID: 22106867 DOI: 10.1111/j.1600-0854.2011.01312.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 11/18/2011] [Accepted: 11/22/2011] [Indexed: 12/22/2022]
Abstract
Microtubule (MT) plus-end-tracking proteins accumulate at MT plus ends for various cellular functions, but their targeting mechanisms are not fully understood (Akhmanova A and Steinmetz MO. Tracking the ends: a dynamic protein network controls the fate of microtubule tips. Nat Rev Mol Cell Biol 2008;9:309-322.). Here, we tested in the filamentous fungus Aspergillus nidulans the requirement for plus-end localization of dynactin p150, a protein essential for dynein function. Deletion of the N-terminal MT-binding region of p150 significantly diminishes the MT plus-end accumulation of both dynein heavy chain and p150, and causes a partial defect in nuclear distribution. Surprisingly, within the MT-binding region, the basic domain is more critical than the CAP-Gly (cytoskeleton-associated protein glycine-rich) domain for maintaining plus-end tracking of p150, as well as for the functions of dynein in nuclear distribution and early endosome movement. Our results show that the basic domain of A. nidulans p150 is important for p150-MT interaction both in vivo and in vitro, and the basic amino acids within this domain are crucial for the plus-end accumulation of p150 in the wild-type background and for the p150-MT interaction in the ΔkinA (kinesin-1) background. We suggest that the basic amino acids are required for the electrostatic interaction between p150 and MTs, which is important for kinesin-1-mediated plus-end targeting of dynactin and dynein in A. nidulans.
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Affiliation(s)
- Xuanli Yao
- Department of Biochemistry and Molecular Biology, The Uniformed Services University, Bethesda, MD, USA
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62
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Bjelić S, De Groot CO, Schärer MA, Jaussi R, Bargsten K, Salzmann M, Frey D, Capitani G, Kammerer RA, Steinmetz MO. Interaction of mammalian end binding proteins with CAP-Gly domains of CLIP-170 and p150(glued). J Struct Biol 2011; 177:160-7. [PMID: 22119847 DOI: 10.1016/j.jsb.2011.11.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/07/2011] [Accepted: 11/07/2011] [Indexed: 10/15/2022]
Abstract
End binding proteins (EBs) track growing microtubule ends and play a master role in organizing dynamic protein networks. Mammalian cells express up to three different EBs (EB1, EB2, and EB3). Besides forming homodimers, EB1 and EB3 also assemble into heterodimers. One group of EB-binding partners encompasses proteins that harbor CAP-Gly domains. The binding properties of the different EBs towards CAP-Gly proteins have not been systematically investigated. This information is, however, important to compare and contrast functional differences. Here we analyzed the interactions between CLIP-170 and p150(glued) CAP-Gly domains with the three EB homodimers and the EB1-EB3 heterodimer. Using isothermal titration calorimetry we observed that some EBs bind to the individual CAP-Gly domains with similar affinities while others interact with their targets with pronounced differences. We further found that the two types of CAP-Gly domains use alternative mechanisms to target the C-terminal domains of EBs. We succeeded to solve the crystal structure of a complex composed of a heterodimer of EB1 and EB3 C-termini together with the CAP-Gly domain of p150(glued). Together, our results provide mechanistic insights into the interaction properties of EBs and offer a molecular framework for the systematic investigation of their functional differences in cells.
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Affiliation(s)
- Saša Bjelić
- Biomolecular Research, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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63
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Meireles AM, Dzhindzhev NS, Ohkura H. Kebab: kinetochore and EB1 associated basic protein that dynamically changes its localisation during Drosophila mitosis. PLoS One 2011; 6:e24174. [PMID: 21912673 PMCID: PMC3166307 DOI: 10.1371/journal.pone.0024174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 08/01/2011] [Indexed: 11/25/2022] Open
Abstract
Microtubule plus ends are dynamic ends that interact with other cellular structures. Microtubule plus end tracking proteins are considered to play important roles in the regulation of microtubule plus ends. Recent studies revealed that EB1 is the central regulator for microtubule plus end tracking proteins by recruiting them to microtubule plus ends through direct interaction. Here we report the identification of a novel Drosophila protein, which we call Kebab (kinetochore and EB1 associated basic protein), through in vitro expression screening for EB1-interacting proteins. Kebab fused to GFP shows a novel pattern of dynamic localisation in mitosis. It localises to kinetochores weakly in metaphase and accumulates progressively during anaphase. In telophase, it associates with microtubules in central-spindle and centrosomal regions. The localisation to kinetochores depends on microtubules. The protein has a domain most similar to the atypical CH domain of Ndc80, and a coiled-coil domain. The interaction with EB1 is mediated by two SxIP motifs but is not required for the localisation. Depletion of Kebab in cultured cells by RNA interference did not show obvious defects in mitotic progression or microtubule organisation. Generation of mutants lacking the kebab gene indicated that Kebab is dispensable for viability and fertility.
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Affiliation(s)
- Ana M. Meireles
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Nikola S. Dzhindzhev
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Hiroyuki Ohkura
- The Wellcome Trust Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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64
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Buey RM, Mohan R, Leslie K, Walzthoeni T, Missimer JH, Menzel A, Bjelić S, Bargsten K, Grigoriev I, Smal I, Meijering E, Aebersold R, Akhmanova A, Steinmetz MO. Insights into EB1 structure and the role of its C-terminal domain for discriminating microtubule tips from the lattice. Mol Biol Cell 2011; 22:2912-23. [PMID: 21737692 PMCID: PMC3154886 DOI: 10.1091/mbc.e11-01-0017] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 05/12/2011] [Accepted: 06/16/2011] [Indexed: 12/31/2022] Open
Abstract
End-binding proteins (EBs) comprise a conserved family of microtubule plus end-tracking proteins. The concerted action of calponin homology (CH), linker, and C-terminal domains of EBs is important for their autonomous microtubule tip tracking, regulation of microtubule dynamics, and recruitment of numerous partners to microtubule ends. Here we report the detailed structural and biochemical analysis of mammalian EBs. Small-angle X-ray scattering, electron microscopy, and chemical cross-linking in combination with mass spectrometry indicate that EBs are elongated molecules with two interacting CH domains, an arrangement reminiscent of that seen in other microtubule- and actin-binding proteins. Removal of the negatively charged C-terminal tail did not affect the overall conformation of EBs; however, it increased the dwell times of EBs on the microtubule lattice in microtubule tip-tracking reconstitution experiments. An even more stable association with the microtubule lattice was observed when the entire negatively charged C-terminal domain of EBs was replaced by a neutral coiled-coil motif. In contrast, the interaction of EBs with growing microtubule tips was not significantly affected by these C-terminal domain mutations. Our data indicate that long-range electrostatic repulsive interactions between the C-terminus and the microtubule lattice drive the specificity of EBs for growing microtubule ends.
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Affiliation(s)
- Rubén M. Buey
- Biomolecular Research, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Renu Mohan
- Department of Cell Biology, Erasmus Medical Center, Rotterdam 3000 CA, Netherlands
| | - Kris Leslie
- Department of Cell Biology, Erasmus Medical Center, Rotterdam 3000 CA, Netherlands
| | - Thomas Walzthoeni
- Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
- Ph.D. Program in Molecular Life Sciences, University of Zürich/ETH Zürich, 8093 Zürich, Switzerland
| | - John H. Missimer
- Biomolecular Research, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Andreas Menzel
- Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Saša Bjelić
- Biomolecular Research, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Katja Bargsten
- Biomolecular Research, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Ilya Grigoriev
- Department of Cell Biology, Erasmus Medical Center, Rotterdam 3000 CA, Netherlands
| | - Ihor Smal
- Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus Medical Center, Rotterdam 3000 CA, Netherlands
| | - Erik Meijering
- Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus Medical Center, Rotterdam 3000 CA, Netherlands
| | - Ruedi Aebersold
- Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
- Faculty of Science, University of Zürich, 8093 Zürich, Switzerland
- Competence Center for Systems Physiology and Metabolic Diseases, 8093 Zürich, Switzerland
| | - Anna Akhmanova
- Ph.D. Program in Molecular Life Sciences, University of Zürich/ETH Zürich, 8093 Zürich, Switzerland
| | - Michel O. Steinmetz
- Biomolecular Research, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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65
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Yu KL, Keijzer N, Hoogenraad CC, Akhmanova A. Isolation of novel +TIPs and their binding partners using affinity purification techniques. Methods Mol Biol 2011; 777:293-316. [PMID: 21773937 DOI: 10.1007/978-1-61779-252-6_21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Microtubule organization and dynamics are controlled by a large set of cellular factors. An important group of microtubule regulators is microtubule plus-end-tracking proteins (+TIPs), which accumulate specifically at the growing microtubule ends, affect different phases of dynamic instability, and link microtubules to various cellular structures. +TIPs include a very diverse set of proteins with widely different structural properties. One of the most conserved and ubiquitous +TIP families are end-binding (EB) proteins, which can track growing microtubule ends autonomously in the absence of any other factors. In contrast, the majority of other known +TIPs cannot recognize the growing microtubule plus ends on their own; instead, they "hitchhike" to the plus ends by interacting with one of the members of the EB family. Therefore, the association with EBs and the ability to track growing microtubule ends are tightly linked, and binding to the EBs can be used to identify new +TIPs. In this chapter, we describe two affinity purification techniques, glutathione S-transferase and biotinylation tag-based pull-down assays that proved to be very useful for the identification of new EB-interacting +TIPs and their binding partners by mass spectrometry. We also discuss cytological techniques that can be applied to confirm plus-end localization of newly identified proteins.
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Affiliation(s)
- Ka Lou Yu
- Department of Cell Biology, Erasmus Medical Center, Rotterdam, The Netherlands
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66
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Galjart N. Plus-end-tracking proteins and their interactions at microtubule ends. Curr Biol 2010; 20:R528-37. [PMID: 20620909 DOI: 10.1016/j.cub.2010.05.022] [Citation(s) in RCA: 173] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microtubules are cytoskeletal elements that are essential for a large number of intracellular processes, including mitosis, cell differentiation and migration, and vesicle transport. In many cells, the microtubule network is organized in a radial manner, with one end of a microtubule (the minus end) embedded near the nucleus and the other end (the plus end) exploring cytoplasmic space, switching between episodes of growth and shrinkage. Mammalian plus-end-tracking proteins (+TIPs) localize to the ends of growing microtubules and regulate both the dynamic behavior of microtubules as well as the interactions of microtubules with other cellular components. Because of these crucial roles, +TIPs and the mechanisms underlying their association with microtubule ends have been intensively investigated. Results indicate that +TIPs reach microtubule ends by motor-mediated transport or diffusion. Individual +TIP molecules exchange rapidly on microtubule end-binding sites that are formed during microtubule polymerization and that have a slower turnover. Most +TIPs associate with the end-binding (EB) proteins, and appear to require these 'core' +TIPs for localization at microtubule ends. Accumulation of +TIPs may also involve structural features of the microtubule end and interactions with other +TIPs. This complexity makes it difficult to assign discrete roles to specific +TIPs. Given that +TIPs concentrate at microtubule ends and that each +TIP binds in a conformationally distinct manner, I propose that the ends of growing microtubules are 'nano-platforms' for productive interactions between selected proteins and that these interactions might persist and be functional elsewhere in the cytoplasm than at the microtubule end at which they originated.
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Affiliation(s)
- Niels Galjart
- Department of Cell Biology and Genetics, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
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Alushin GM, Ramey VH, Pasqualato S, Ball DA, Grigorieff N, Musacchio A, Nogales E. The Ndc80 kinetochore complex forms oligomeric arrays along microtubules. Nature 2010; 467:805-10. [PMID: 20944740 PMCID: PMC2957311 DOI: 10.1038/nature09423] [Citation(s) in RCA: 247] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 08/13/2010] [Indexed: 12/18/2022]
Abstract
The Ndc80 complex is a key site of regulated kinetochore-microtubule attachment (a process required for cell division), but the molecular mechanism underlying its function remains unknown. Here we present a subnanometre-resolution cryo-electron microscopy reconstruction of the human Ndc80 complex bound to microtubules, sufficient for precise docking of crystal structures of the component proteins. We find that the Ndc80 complex binds the microtubule with a tubulin monomer repeat, recognizing α- and β-tubulin at both intra- and inter-tubulin dimer interfaces in a manner that is sensitive to tubulin conformation. Furthermore, Ndc80 complexes self-associate along protofilaments through interactions mediated by the amino-terminal tail of the NDC80 protein, which is the site of phospho-regulation by Aurora B kinase. The complex's mode of interaction with the microtubule and its oligomerization suggest a mechanism by which Aurora B could regulate the stability of load-bearing kinetochore-microtubule attachments.
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Affiliation(s)
- Gregory M Alushin
- Biophysics Graduate Group, University of California, Berkeley, California 94720, USA
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68
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Jaulin F, Kreitzer G. KIF17 stabilizes microtubules and contributes to epithelial morphogenesis by acting at MT plus ends with EB1 and APC. ACTA ACUST UNITED AC 2010; 190:443-60. [PMID: 20696710 PMCID: PMC2922650 DOI: 10.1083/jcb.201006044] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epithelial polarization is associated with selective stabilization and reorganization of microtubule (MT) arrays. However, upstream events and downstream consequences of MT stabilization during epithelial morphogenesis are still unclear. We show that the anterograde kinesin KIF17 localizes to MT plus ends, stabilizes MTs, and affects epithelial architecture. Targeting of KIF17 to plus ends of growing MTs requires kinesin motor activity and interaction with EB1. In turn, KIF17 participates in localizing adenomatous polyposis coli (APC) to the plus ends of a subset of MTs. We found that KIF17 affects MT dynamics, polymerization rates, and MT plus end stabilization to generate posttranslationally acetylated MTs. Depletion of KIF17 from cells growing in three-dimensional matrices results in aberrant epithelial cysts that fail to generate a single central lumen and to polarize apical markers. These findings implicate KIF17 in MT stabilization events that contribute to epithelial polarization and morphogenesis.
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Affiliation(s)
- Fanny Jaulin
- Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY 10021, USA
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69
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Ahmed S, Sun S, Siglin AE, Polenova T, Williams JC. Disease-associated mutations in the p150(Glued) subunit destabilize the CAP-gly domain. Biochemistry 2010; 49:5083-5. [PMID: 20518521 PMCID: PMC2938955 DOI: 10.1021/bi100235z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Point mutations within the CAP-gly domain of the p150(Glued) subunit of the dynactin complex have been identified in patients with distal spinal bulbar muscular atrophy (dSBMA) and Perry's syndrome. Herein, we show by CD and NMR experiments that each mutated CAP-gly domain is folded but less stable than the wild-type (WT) domain. We also demonstrate that the domains harboring these mutations bind to microtubules but fail to bind to EB1. These data indicate that these disease-associated, point mutations affect the stability of this domain and inhibit their interaction with EB1 but do not inhibit their interaction with microtubules.
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Affiliation(s)
- Shubbir Ahmed
- Department of Molecular Medicine, Beckman Research Institute at City of Hope
| | - Shangjin Sun
- Department of Chemistry and Biochemistry, University of Delaware
| | - Amanda E. Siglin
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware
| | - John C. Williams
- Department of Molecular Medicine, Beckman Research Institute at City of Hope
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70
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Skube SB, Chaverri JM, Goodson HV. Effect of GFP tags on the localization of EB1 and EB1 fragments in vivo. Cytoskeleton (Hoboken) 2010; 67:1-12. [PMID: 19701929 DOI: 10.1002/cm.20409] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
EB1 is a microtubule plus-end tracking protein that plays a central role in the regulation of microtubule (MT) dynamics. GFP-tagged EB1 constructs are commonly used to study EB1 itself and also as markers of dynamic MT plus ends. To properly interpret these studies, it is important to understand the impact of tags on the behavior of EB1 and other proteins in vivo. To address this problem and improve understanding of EB1 function, we surveyed the localization of expressed EB1 fragments and investigated whether GFP tags alter these localizations. We found that neither N-terminal nor C-terminal tags are benign: tagged EB1 and EB1 fragments generally behave differently from their untagged counterparts. N-terminal tags significantly compromise the ability of expressed EB1 proteins to bind MTs and/or track MT plus ends, although they leave some MT-binding ability intact. C-terminally tagged EB1 constructs have localizations similar to the untagged constructs, initially suggesting that they are benign. However, most constructs tagged at either end cause CLIP-170 to disappear from MT plus ends. This effect is opposite to that of untagged full-length EB1, which recruits CLIP-170 to MTs. These observations demonstrate that although EB1-GFP can be a powerful tool for studying microtubule dynamics, it should be used carefully because it may alter the system that it is being used to study. In addition, some untagged fragments had unexpected localizations. In particular, an EB1 construct lacking the coiled-coil tracks MT plus ends, though weakly, providing evidence against the idea that EB1 +TIP behavior requires dimerization.
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Affiliation(s)
- Susan B Skube
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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71
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Blake-Hodek KA, Cassimeris L, Huffaker TC. Regulation of microtubule dynamics by Bim1 and Bik1, the budding yeast members of the EB1 and CLIP-170 families of plus-end tracking proteins. Mol Biol Cell 2010; 21:2013-23. [PMID: 20392838 PMCID: PMC2883945 DOI: 10.1091/mbc.e10-02-0083] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Bim1 promotes microtubule assembly in vitro, primarily by decreasing the frequency of catastrophes. In contrast, Bik1 inhibits microtubule assembly by slowing growth and, consequently, promoting catastrophes. These proteins interact to form a complex that affects microtubule dynamics in much the same way as Bim1 alone. Microtubule dynamics are regulated by plus-end tracking proteins (+TIPs), which bind microtubule ends and influence their polymerization properties. In addition to binding microtubules, most +TIPs physically associate with other +TIPs, creating a complex web of interactions. To fully understand how +TIPs regulate microtubule dynamics, it is essential to know the intrinsic biochemical activities of each +TIP and how +TIP interactions affect these activities. Here, we describe the activities of Bim1 and Bik1, two +TIP proteins from budding yeast and members of the EB1 and CLIP-170 families, respectively. We find that purified Bim1 and Bik1 form homodimers that interact with each other to form a tetramer. Bim1 binds along the microtubule lattice but with highest affinity for the microtubule end; however, Bik1 requires Bim1 for localization to the microtubule lattice and end. In vitro microtubule polymerization assays show that Bim1 promotes microtubule assembly, primarily by decreasing the frequency of catastrophes. In contrast, Bik1 inhibits microtubule assembly by slowing growth and, consequently, promoting catastrophes. Interestingly, the Bim1-Bik1 complex affects microtubule dynamics in much the same way as Bim1 alone. These studies reveal new activities for EB1 and CLIP-170 family members and demonstrate how interactions between two +TIP proteins influence their activities.
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72
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Komaki S, Abe T, Coutuer S, Inzé D, Russinova E, Hashimoto T. Nuclear-localized subtype of end-binding 1 protein regulates spindle organization in Arabidopsis. J Cell Sci 2010; 123:451-9. [PMID: 20067996 DOI: 10.1242/jcs.062703] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
End-binding 1 (EB1) proteins are evolutionarily conserved plus-end-tracking proteins that localize to growing microtubule plus ends where they regulate microtubule dynamics and interactions with intracellular targets. Animal EB1 proteins have acidic C-terminal tails that might induce an autoinhibitory conformation. Although EB1 proteins with the same structural features occur in plants (EB1a and EB1b in Arabidopsis thaliana), a variant form (EB1c) is present that lacks the characteristic tail. We show that in Arabidopsis the tail region of EB1b, but not of EB1c, inhibits microtubule assembly in vitro. EB1a and EB1b form heterodimers with each other, but not with EB1c. Furthermore, the EB1 genes are expressed in various cell types of Arabidopsis, but the expression of EB1c is particularly strong in the meristematic cells where it is targeted to the nucleus by a nuclear localization signal in the C-terminal tail. Reduced expression of EB1c compromised the alignment of spindle and phragmoplast microtubules and caused frequent lagging of separating chromosomes at anaphase. Roots of the eb1c mutant were hypersensitive to a microtubule-disrupting drug and complete rescue of the mutant phenotype required the tail region of EB1c. These results suggest that a plant-specific EB1 subtype has evolved to function preferentially on the spindle microtubules by accumulating in the prophase nucleus.
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Affiliation(s)
- Shinichiro Komaki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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73
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Structural and mechanistic insights into microtubule end-binding proteins. Curr Opin Cell Biol 2010; 22:88-95. [DOI: 10.1016/j.ceb.2009.10.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 10/23/2009] [Accepted: 10/31/2009] [Indexed: 12/17/2022]
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74
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Gouveia SM, Akhmanova A. Cell and Molecular Biology of Microtubule Plus End Tracking Proteins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 285:1-74. [DOI: 10.1016/b978-0-12-381047-2.00001-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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75
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Abstract
Eukaryotic cells use cytoskeletal motor proteins to transport many different intracellular cargos. Numerous kinesins and myosins have evolved to cope with the various transport needs that have arisen during eukaryotic evolution. Surprisingly, a single cytoplasmic dynein (a minus end-directed microtubule motor) carries out similarly diverse transport activities as the many different types of kinesin. How is dynein coupled to its wide range of cargos and how is it spatially and temporally regulated? The answer could lie in the several multifunctional adaptors, including dynactin, lissencephaly 1, nuclear distribution protein E (NUDE) and NUDE-like, Bicaudal D, Rod-ZW10-Zwilch and Spindly, that regulate dynein function and localization.
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76
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Abstract
+TIPs (plus-end tracking proteins) are an increasing group of molecules that localize preferentially to the end of growing microtubules. +TIPs regulate microtubule dynamics and contribute to the organization of the microtubular network within the cell. Thus they participate in a wide range of cellular processes including cell division, motility and morphogenesis. EB1 (end-binding 1) is a highly conserved key member of the +TIP group that has been shown to modulate microtubule dynamics both in vitro and in cells. EB1 is involved in accurate chromosome segregation during mitosis and in the polarization of the microtubule cytoskeleton in migrating cells. Here, we review recent in vitro studies that have started to reveal a regulating activity of EB1, and its yeast orthologue Mal3p, on microtubule structure. In particular, we examine how EB1-mediated changes in the microtubule architecture may explain its effects on microtubule dynamics.
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77
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Zhu ZC, Gupta KK, Slabbekoorn AR, Paulson BA, Folker ES, Goodson HV. Interactions between EB1 and microtubules: dramatic effect of affinity tags and evidence for cooperative behavior. J Biol Chem 2009; 284:32651-61. [PMID: 19778897 DOI: 10.1074/jbc.m109.013466] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Plus end tracking proteins (+TIPs) are a unique group of microtubule binding proteins that dynamically track microtubule (MT) plus ends. EB1 is a highly conserved +TIP with a fundamental role in MT dynamics, but it remains poorly understood in part because reported EB1 activities have differed considerably. One reason for this inconsistency could be the variable presence of affinity tags used for EB1 purification. To address this question and establish the activity of native EB1, we have measured the MT binding and tubulin polymerization activities of untagged EB1 and EB1 fragments and compared them with those of His-tagged EB1 proteins. We found that N-terminal His tags directly influence the interaction between EB1 and MTs, significantly increasing both affinity and activity, and that small amounts of His-tagged proteins act synergistically with larger amounts of untagged proteins. Moreover, the binding ratio between EB1 and tubulin can exceed 1:1, and EB1-MT binding curves do not fit simple binding models. These observations demonstrate that EB1 binding is not limited to the MT seam, and they suggest that EB1 binds cooperatively to MTs. Finally, we found that removal of tubulin C-terminal tails significantly reduces EB1 binding, indicating that EB1-tubulin interactions are mediated in part by the same tubulin acidic tails utilized by other MAPs. These binding relationships are important for helping to elucidate the complex of proteins at the MT tip.
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Affiliation(s)
- Zhiqing C Zhu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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78
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Zimniak T, Stengl K, Mechtler K, Westermann S. Phosphoregulation of the budding yeast EB1 homologue Bim1p by Aurora/Ipl1p. ACTA ACUST UNITED AC 2009; 186:379-91. [PMID: 19667128 PMCID: PMC2728395 DOI: 10.1083/jcb.200901036] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
EB1 (end binding 1) proteins have emerged as central regulators of microtubule (MT) plus ends in all eukaryotes, but molecular mechanisms controlling the activity of these proteins are poorly understood. In this study, we show that the budding yeast EB1 protein Bim1p is regulated by Aurora B/Ipl1p-mediated multisite phosphorylation. Bim1p forms a stable complex with Ipl1p and is phosphorylated on a cluster of six Ser residues in the flexible linker connecting the calponin homology (CH) and EB1 domains. Using reconstitution of plus end tracking in vitro and total internal reflection fluorescence microscopy, we show that dimerization of Bim1p and the presence of the linker domain are both required for efficient tip tracking and that linker phosphorylation removes Bim1p from static and dynamic MTs. Bim1 phosphorylation occurs during anaphase in vivo, and it is required for normal spindle elongation kinetics and an efficient disassembly of the spindle midzone. Our results define a mechanism for the use and regulation of CH domains in an EB1 protein.
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Affiliation(s)
- Tomasz Zimniak
- Research Institute of Molecular Pathology, 1030 Vienna, Austria
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79
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Sun S, Siglin A, Williams JC, Polenova T. Solid-State and Solution NMR Studies of the CAP-Gly Domain of Mammalian Dynactin and Its Interaction with Microtubules. J Am Chem Soc 2009; 131:10113-26. [PMID: 19580321 DOI: 10.1021/ja902003u] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Shangjin Sun
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, and Department of Molecular Medicine, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, California 91010
| | - Amanda Siglin
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, and Department of Molecular Medicine, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, California 91010
| | - John C. Williams
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, and Department of Molecular Medicine, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, California 91010
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, and Department of Molecular Medicine, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, California 91010
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80
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Fong KW, Hau SY, Kho YS, Jia Y, He L, Qi RZ. Interaction of CDK5RAP2 with EB1 to track growing microtubule tips and to regulate microtubule dynamics. Mol Biol Cell 2009; 20:3660-70. [PMID: 19553473 DOI: 10.1091/mbc.e09-01-0009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mutations in cdk5rap2 are linked to autosomal recessive primary microcephaly, and attention has been paid to its function at centrosomes. In this report, we demonstrate that CDK5RAP2 localizes to microtubules and concentrates at the distal tips in addition to centrosomal localization. CDK5RAP2 interacts directly with EB1, a prototypic member of microtubule plus-end tracking proteins, and contains the basic and Ser-rich motif responsible for EB1 binding. The EB1-binding motif is conserved in the CDK5RAP2 sequences of chimpanzee, bovine, and dog but not in those of rat and mouse, suggesting a function gained during the evolution of mammals. The mutation of the Ile/Leu-Pro dipeptide within the motif abolishes EB1 interaction and plus-end attachment. In agreement with the mutational analysis, suppression of EB1 expression inhibits microtubule tip-tracking of CDK5RAP2. We have also found that the CDK5RAP2-EB1 complex regulates microtubule dynamics and stability. CDK5RAP2 depletion by RNA interference impacts the dynamic behaviors of microtubules. The CDK5RAP2-EB1 complex induces microtubule bundling and acetylation when expressed in cell cultures and stimulates microtubule assembly and bundle formation in vitro. Collectively, these results show that CDK5RAP2 targets growing microtubule tips in association with EB1 to regulate microtubule dynamics.
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Affiliation(s)
- Ka-Wing Fong
- Department of Biochemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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81
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Kronja I, Kruljac-Letunic A, Caudron-Herger M, Bieling P, Karsenti E. XMAP215-EB1 interaction is required for proper spindle assembly and chromosome segregation in Xenopus egg extract. Mol Biol Cell 2009; 20:2684-96. [PMID: 19369422 DOI: 10.1091/mbc.e08-10-1051] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In metaphase Xenopus egg extracts, global microtubule growth is mainly promoted by two unrelated microtubule stabilizers, end-binding protein 1 (EB1) and XMAP215. Here, we explore their role and potential redundancy in the regulation of spindle assembly and function. We find that at physiological expression levels, both proteins are required for proper spindle architecture: Spindles assembled in the absence of EB1 or at decreased XMAP215 levels are short and frequently multipolar. Moreover, the reduced density of microtubules at the equator of DeltaEB1 or DeltaXMAP215 spindles leads to faulty kinetochore-microtubule attachments. These spindles also display diminished poleward flux rates and, upon anaphase induction, they neither segregate chromosomes nor reorganize into interphasic microtubule arrays. However, EB1 and XMAP215 nonredundantly regulate spindle assembly because an excess of XMAP215 can compensate for the absence of EB1, whereas the overexpression of EB1 cannot substitute for reduced XMAP215 levels. Our data indicate that EB1 could positively regulate XMAP215 by promoting its binding to the microtubules. Finally, we show that disruption of the mitosis-specific XMAP215-EB1 interaction produces a phenotype similar to that of either EB1 or XMAP215 depletion. Therefore, the XMAP215-EB1 interaction is required for proper spindle organization and chromosome segregation in Xenopus egg extracts.
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Affiliation(s)
- Iva Kronja
- Department of Cell Biology and Biophysics, European Molecular Biology Laboratory, Heidelberg, Germany
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82
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Komarova Y, De Groot CO, Grigoriev I, Gouveia SM, Munteanu EL, Schober JM, Honnappa S, Buey RM, Hoogenraad CC, Dogterom M, Borisy GG, Steinmetz MO, Akhmanova A. Mammalian end binding proteins control persistent microtubule growth. ACTA ACUST UNITED AC 2009; 184:691-706. [PMID: 19255245 PMCID: PMC2686402 DOI: 10.1083/jcb.200807179] [Citation(s) in RCA: 304] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
End binding proteins (EBs) are highly conserved core components of microtubule plus-end tracking protein networks. Here we investigated the roles of the three mammalian EBs in controlling microtubule dynamics and analyzed the domains involved. Protein depletion and rescue experiments showed that EB1 and EB3, but not EB2, promote persistent microtubule growth by suppressing catastrophes. Furthermore, we demonstrated in vitro and in cells that the EB plus-end tracking behavior depends on the calponin homology domain but does not require dimer formation. In contrast, dimerization is necessary for the EB anti-catastrophe activity in cells; this explains why the EB1 dimerization domain, which disrupts native EB dimers, exhibits a dominant-negative effect. When microtubule dynamics is reconstituted with purified tubulin, EBs promote rather than inhibit catastrophes, suggesting that in cells EBs prevent catastrophes by counteracting other microtubule regulators. This probably occurs through their action on microtubule ends, because catastrophe suppression does not require the EB domains needed for binding to known EB partners.
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Affiliation(s)
- Yulia Komarova
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA
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83
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84
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85
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Plevin MJ, Hayashi I, Ikura M. Characterization of a Conserved “Threonine Clasp” in CAP-Gly Domains: Role of a Functionally Critical OH/π Interaction in Protein Recognition. J Am Chem Soc 2008; 130:14918-9. [DOI: 10.1021/ja805576n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael J. Plevin
- Division of Signaling Biology, Ontario Cancer Institute, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L7, Canada
| | - Ikuko Hayashi
- Division of Signaling Biology, Ontario Cancer Institute, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L7, Canada
| | - Mitsuhiko Ikura
- Division of Signaling Biology, Ontario Cancer Institute, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L7, Canada
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86
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Capturing protein tails by CAP-Gly domains. Trends Biochem Sci 2008; 33:535-45. [PMID: 18835717 DOI: 10.1016/j.tibs.2008.08.006] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 08/29/2008] [Accepted: 08/29/2008] [Indexed: 12/29/2022]
Abstract
Cytoskeleton-associated protein-glycine-rich (CAP-Gly) domains are protein-interaction modules implicated in important cellular processes and in hereditary human diseases. A prominent function of CAP-Gly domains is to bind to C-terminal EEY/F-COO(-) sequence motifs present in alpha-tubulin and in some microtubule-associated protein tails; however, CAP-Gly domains also interact with other structural elements including end-binding homology domains, zinc-finger motifs and proline-rich sequences. Recent findings unravelled the link between tubulin tyrosination and CAP-Gly-protein recruitment to microtubules. They further provided a molecular basis for understanding the role of CAP-Gly domains in controlling dynamic cellular processes including the tracking and regulation of microtubule ends. It is becoming increasingly clear that CAP-Gly domains are also involved in coordinating complex and diverse aspects of cell architecture and signalling.
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87
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Abstract
Dynactin is a multisubunit protein complex necessary for dynein function. Here, we investigated the function of dynactin in budding yeast. Loss of dynactin impaired movement and positioning of the mitotic spindle, similar to loss of dynein. Dynactin subunits required for function included p150(Glued), dynamitin, actin-related protein (Arp) 1 and p24. Arp10 and capping protein were dispensable, even in combination. All dynactin subunits tested localized to dynamic plus ends of cytoplasmic microtubules, to stationary foci on the cell cortex and to spindle pole bodies. The number of molecules of dynactin in those locations was small, less than five. In the absence of dynactin, dynein accumulated at plus ends and did not appear at the cell cortex, consistent with a role for dynactin in offloading dynein from the plus end to the cortex. Dynein at the plus end was necessary for dynactin plus-end targeting. p150(Glued) was the only dynactin subunit sufficient for plus-end targeting. Interactions among the subunits support a molecular model that resembles the current model for brain dynactin in many respects; however, three subunits at the pointed end of brain dynactin appear to be absent from yeast.
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Affiliation(s)
- Jeffrey K Moore
- Department of Cell Biology and Physiology, Washington University, Saint Louis, MO 63110, USA
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88
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EB1 regulates microtubule dynamics and tubulin sheet closure in vitro. Nat Cell Biol 2008; 10:415-21. [PMID: 18364701 DOI: 10.1038/ncb1703] [Citation(s) in RCA: 208] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 02/25/2008] [Indexed: 11/08/2022]
Abstract
End binding 1 (EB1) is a plus-end-tracking protein (+TIP) that localizes to microtubule plus ends where it modulates their dynamics and interactions with intracellular organelles. Although the regulating activity of EB1 on microtubule dynamics has been studied in cells and purified systems, the molecular mechanisms involved in its specific activity are still unclear. Here, we describe how EB1 regulates the dynamics and structure of microtubules assembled from pure tubulin. We found that EB1 stimulates spontaneous nucleation and growth of microtubules, and promotes both catastrophes (transitions from growth to shrinkage) and rescues (reverse events). Electron cryomicroscopy showed that EB1 induces the initial formation of tubulin sheets, which rapidly close into the common 13-protofilament-microtubule architecture. Our results suggest that EB1 favours the lateral association of free tubulin at microtubule-sheet edges, thereby stimulating nucleation, sheet growth and closure. The reduction of sheet length at microtubule growing-ends together with the elimination of stressed microtubule lattices may account for catastrophes. Conversely, occasional binding of EB1 to the microtubule lattice may induce rescues.
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89
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Akhmanova A, Steinmetz MO. Tracking the ends: a dynamic protein network controls the fate of microtubule tips. Nat Rev Mol Cell Biol 2008; 9:309-22. [PMID: 18322465 DOI: 10.1038/nrm2369] [Citation(s) in RCA: 788] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Microtubule plus-end tracking proteins (+TIPs) are a diverse group of evolutionarily conserved cellular factors that accumulate at the ends of growing microtubules. They form dynamic networks through the interaction of a limited set of protein modules, repeat sequences and linear motifs that bind to each other with moderate affinities. +TIPs regulate different aspects of cell architecture by controlling microtubule dynamics, microtubule interactions with cellular structures and signalling factors, and the forces that are exerted on microtubule networks.
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Affiliation(s)
- Anna Akhmanova
- Department of Cell Biology, Erasmus Medical Center, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands.
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90
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Gao J, Huo L, Sun X, Liu M, Li D, Dong JT, Zhou J. The tumor suppressor CYLD regulates microtubule dynamics and plays a role in cell migration. J Biol Chem 2008; 283:8802-9. [PMID: 18222923 DOI: 10.1074/jbc.m708470200] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The familial cylindromatosis tumor suppressor CYLD is known to contain three cytoskeleton-associated protein glycine-rich (CAP-Gly) domains, which exist in a number of microtubule-binding proteins and are responsible for their association with microtubules. However, it remains elusive whether CYLD interacts with microtubules and, if so, whether the interaction is mediated by the CAP-Gly domains. In this study, our data demonstrate that CYLD associates with microtubules both in cells and in vitro, and the first CAP-Gly domain of CYLD is mainly responsible for the interaction. Knockdown of cellular CYLD expression dramatically delays microtubule regrowth after nocodazole washout, indicating an activity for CYLD in promoting microtubule assembly. Our data further demonstrate that CYLD enhances tubulin polymerization into microtubules by lowering the critical concentration for microtubule assembly. In addition, we have identified by wound healing assay a critical role for CYLD in mediating cell migration and found that its first CAP-Gly domain is required for this activity. Thus CYLD joins a growing list of CAP-Gly domain-containing proteins that regulate microtubule dynamics and function.
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Affiliation(s)
- Jinmin Gao
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, China
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91
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Lee T, Langford KJ, Askham JM, Brüning-Richardson A, Morrison EE. MCAK associates with EB1. Oncogene 2007; 27:2494-500. [DOI: 10.1038/sj.onc.1210867] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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92
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Abstract
Microtubules (MTs) are highly dynamic polymers, which control many aspects of cellular architecture. Growing MT plus ends accumulate a specific set of evolutionary conserved factors, the so-called MT plus-end-tracking proteins (+TIPs). +TIPs regulate MT dynamics and the reciprocal interactions of MTs with the cell cortex, mitotic kinetochores or different cellular organelles. Most +TIPs can directly bind to MTs, but the molecular mechanisms of their specific targeting to the growing plus ends remain poorly understood. Recent studies suggest that the members of one particular +TIP family, EB1 and its homologues, are present in all eucaryotic kingdoms, interact directly with the majority of other known plus-end-associated proteins and may be responsible for their specific accumulation at the MT tips.
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Affiliation(s)
- Gideon Lansbergen
- MGC Department of Cell Biology, Erasmus Medical Center, 3000 DR Rotterdam, the Netherlands
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93
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Slep KC, Vale RD. Structural basis of microtubule plus end tracking by XMAP215, CLIP-170, and EB1. Mol Cell 2007; 27:976-91. [PMID: 17889670 PMCID: PMC2052927 DOI: 10.1016/j.molcel.2007.07.023] [Citation(s) in RCA: 207] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 06/27/2007] [Accepted: 07/17/2007] [Indexed: 02/01/2023]
Abstract
Microtubule plus end binding proteins (+TIPs) localize to the dynamic plus ends of microtubules, where they stimulate microtubule growth and recruit signaling molecules. Three main +TIP classes have been identified (XMAP215, EB1, and CLIP-170), but whether they act upon microtubule plus ends through a similar mechanism has not been resolved. Here, we report crystal structures of the tubulin binding domains of XMAP215 (yeast Stu2p and Drosophila Msps), EB1 (yeast Bim1p and human EB1), and CLIP-170 (human), which reveal diverse tubulin binding interfaces. Functional studies, however, reveal a common property that native or artificial dimerization of tubulin binding domains (including chemically induced heterodimers of EB1 and CLIP-170) induces tubulin nucleation/assembly in vitro and, in most cases, plus end tracking in living cells. We propose that +TIPs, although diverse in structure, share a common property of multimerizing tubulin, thus acting as polymerization chaperones that aid in subunit addition to the microtubule plus end.
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Affiliation(s)
- Kevin C Slep
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
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94
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Hayashi I, Plevin MJ, Ikura M. CLIP170 autoinhibition mimics intermolecular interactions with p150Glued or EB1. Nat Struct Mol Biol 2007; 14:980-1. [PMID: 17828275 DOI: 10.1038/nsmb1299] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 08/10/2007] [Indexed: 01/30/2023]
Abstract
CLIP170 and p150(Glued) localize to the plus ends of growing microtubules. Using crystallography and NMR, we show that autoinhibitory interactions within CLIP170 use the same binding determinants as CLIP170's intermolecular interactions with p150(Glued). These interactions have both similar and distinct features when compared with the p150(Glued)-EB1 complex. Our data thus demonstrate that regulation of microtubule dynamics by plus end-tracking proteins (+TIPs) occurs through direct competition between homologous binding interfaces.
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Affiliation(s)
- Ikuko Hayashi
- Division of Signaling Biology, Ontario Cancer Institute, University of Toronto, 101 College Street, Toronto, Ontario, M5G 1L7, Canada.
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95
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Weisbrich A, Honnappa S, Jaussi R, Okhrimenko O, Frey D, Jelesarov I, Akhmanova A, Steinmetz MO. Structure-function relationship of CAP-Gly domains. Nat Struct Mol Biol 2007; 14:959-67. [PMID: 17828277 DOI: 10.1038/nsmb1291] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 07/12/2007] [Indexed: 11/09/2022]
Abstract
In all eukaryotes, CAP-Gly proteins control important cellular processes. The molecular mechanisms underlying the functions of CAP-Gly domains, however, are still poorly understood. Here we use the complex formed between the CAP-Gly domain of p150(glued) and the C-terminal zinc knuckle of CLIP170 as a model system to explore the structure-function relationship of CAP-Gly-mediated protein interactions. We demonstrate that the conserved GKNDG motif of CAP-Gly domains is responsible for targeting to the C-terminal EEY/F sequence motifs of CLIP170, EB proteins and microtubules. The CAP-Gly-EEY/F interaction is essential for the recruitment of the dynactin complex by CLIP170 and for activation of CLIP170. Our findings define the molecular basis of CAP-Gly domain function, including the tubulin detyrosination-tyrosination cycle. They further establish fundamental roles for the interaction between CAP-Gly proteins and C-terminal EEY/F sequence motifs in regulating complex and dynamic cellular processes.
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Affiliation(s)
- Anke Weisbrich
- Biomolecular Research, Structural Biology, Paul Scherrer Insititut, CH-5232 Villigen PSI, Switzerland
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96
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Dawson SC, Sagolla MS, Mancuso JJ, Woessner DJ, House SA, Fritz-Laylin L, Cande WZ. Kinesin-13 regulates flagellar, interphase, and mitotic microtubule dynamics in Giardia intestinalis. EUKARYOTIC CELL 2007; 6:2354-64. [PMID: 17766466 PMCID: PMC2168246 DOI: 10.1128/ec.00128-07] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Microtubule depolymerization dynamics in the spindle are regulated by kinesin-13, a nonprocessive kinesin motor protein that depolymerizes microtubules at the plus and minus ends. Here we show that a single kinesin-13 homolog regulates flagellar length dynamics, as well as other interphase and mitotic dynamics in Giardia intestinalis, a widespread parasitic diplomonad protist. Both green fluorescent protein-tagged kinesin-13 and EB1 (a plus-end tracking protein) localize to the plus ends of mitotic and interphase microtubules, including a novel localization to the eight flagellar tips, cytoplasmic anterior axonemes, and the median body. The ectopic expression of a kinesin-13 (S280N) rigor mutant construct caused significant elongation of the eight flagella with significant decreases in the median body volume and resulted in mitotic defects. Notably, drugs that disrupt normal interphase and mitotic microtubule dynamics also affected flagellar length in Giardia. Our study extends recent work on interphase and mitotic kinesin-13 functioning in metazoans to include a role in regulating flagellar length dynamics. We suggest that kinesin-13 universally regulates both mitotic and interphase microtubule dynamics in diverse microbial eukaryotes and propose that axonemal microtubules are subject to the same regulation of microtubule dynamics as other dynamic microtubule arrays. Finally, the present study represents the first use of a dominant-negative strategy to disrupt normal protein function in Giardia and provides important insights into giardial microtubule dynamics with relevance to the development of antigiardial compounds that target critical functions of kinesins in the giardial life cycle.
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Affiliation(s)
- Scott C Dawson
- Department of Molecular and Cell Biology, University of California-Berkeley, 341 LSA Bldg., Berkeley, California 94720, USA.
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97
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Hume AN, Ushakov DS, Tarafder AK, Ferenczi MA, Seabra MC. Rab27a and MyoVa are the primary Mlph interactors regulating melanosome transport in melanocytes. J Cell Sci 2007; 120:3111-22. [PMID: 17698919 DOI: 10.1242/jcs.010207] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Melanosome transport in melanocytes is a model system for the study of cytoskeletal regulation of intracellular transport. Melanophilin (Mlph) is a Rab27a- and myosin Va (MyoVa)-binding protein that regulates this process. Using yeast two-hybrid screening, we identified MT plus-end binding protein (EB1) as a melanocyte-expressed Mlph-interacting protein. To address the role of EB1 versus Rab27a and MyoVa interactions in Mlph targeting and function, we used siRNA and Mlph mutations to specifically disrupt each interaction in cultured melanocytes. Using the Mlph R35W mutant that blocks Mlph-Rab27a interaction and Rab27a siRNA we show this interaction is required for melanosome targeting and stability of Mlph. Mutants and siRNA that affect Mlph-MyoVa and Mlph-EB1 interactions reveal that while neither MyoVa nor EB1 affect Mlph targeting to melanosomes, MyoVa but not EB1 interaction is required for transport of melanosomes to peripheral dendrites. We propose that Mlph is targeted to and/or stabilised on melanosomes by Rab27a, and then recruits MyoVa, which provides additional stability to the complex and allows melanosomes to transfer from MT to actin-based transport and achieve peripheral distribution. EB1 appears to be non-essential to this process in cultured melanocytes, which suggests that it plays a redundant role and/or is required for melanocyte/keratinocyte contacts and melanosome transfer.
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Affiliation(s)
- Alistair N Hume
- Molecular and Cellular Medicine, National Heart and Lung Institute, Imperial College London, London, SW7 2AZ, UK.
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98
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Mishima M, Maesaki R, Kasa M, Watanabe T, Fukata M, Kaibuchi K, Hakoshima T. Structural basis for tubulin recognition by cytoplasmic linker protein 170 and its autoinhibition. Proc Natl Acad Sci U S A 2007; 104:10346-51. [PMID: 17563362 PMCID: PMC1965516 DOI: 10.1073/pnas.0703876104] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytoplasmic linker protein 170 (CLIP-170) is a prototype of the plus end-tracking proteins that regulate microtubule dynamics, but it is obscure how CLIP-170 recognizes the microtubule plus end and contributes to polymerization rescue. Crystallographic, NMR, and mutation studies of two tandem cytoskeleton-associated protein glycine-rich (CAP-Gly) domains of CLIP-170, CAP-Gly-1 and CAP-Gly-2, revealed positively charged basic grooves of both CAP-Gly domains for tubulin binding, whereas the CAP-Gly-2 domain possesses a more basic groove and directly binds the EExEEY/F motif of the C-terminal acidic-tail ends of alpha-tubulin. Notably, the p150(Glued) CAP-Gly domain that is furnished with a less positively charged surface only weakly interacts with the alpha-tubulin acidic tail. Mutation studies showed that this acidic sextette motif is the minimum region for CAP-Gly binding. The C-terminal zinc knuckle domains of CLIP-170 bind the basic groove to inhibit the binding to the acidic tails. These results provide a structural basis for the proposed CLIP-170 copolymerization with tubulin on the microtubule plus end. CLIP-170 strongly binds the acidic tails of EB1 as well as those of alpha-tubulins, indicating that EB1 localized at the plus end contributes to CLIP-170 recruitment to the plus end. We suggest that CLIP-170 stimulates microtubule polymerization and/or nucleation by neutralizing the negative charges of tubulins with the highly positive charges of the CLIP-170 CAP-Gly domains. Once CLIP-170 binds microtubule, the released zinc knuckle domain may serve to recruit dynein to the plus end by interacting with p150(Glued) and LIS1. Thus, our structures provide the structural basis for the specific dynein loading on the microtubule plus end.
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Affiliation(s)
| | - Ryoko Maesaki
- Structural Biology Laboratory, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Miyuki Kasa
- Structural Biology Laboratory, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan; and
| | - Takashi Watanabe
- Department of Cell Pharmacology, Nagoya University, Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 466-8550, Japan
| | - Masaki Fukata
- Department of Cell Pharmacology, Nagoya University, Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 466-8550, Japan
| | - Kozo Kaibuchi
- Department of Cell Pharmacology, Nagoya University, Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 466-8550, Japan
| | - Toshio Hakoshima
- *Graduate School of Biological Science
- Structural Biology Laboratory, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan; and
- To whom correspondence should be addressed at: Structural Biology Laboratory, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan. E-mail:
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99
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Kim H, Ling SC, Rogers GC, Kural C, Selvin PR, Rogers SL, Gelfand VI. Microtubule binding by dynactin is required for microtubule organization but not cargo transport. ACTA ACUST UNITED AC 2007; 176:641-51. [PMID: 17325206 PMCID: PMC2064022 DOI: 10.1083/jcb.200608128] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dynactin links cytoplasmic dynein and other motors to cargo and is involved in organizing radial microtubule arrays. The largest subunit of dynactin, p150glued, binds the dynein intermediate chain and has an N-terminal microtubule-binding domain. To examine the role of microtubule binding by p150glued, we replaced the wild-type p150glued in Drosophila melanogaster S2 cells with mutant ΔN-p150 lacking residues 1–200, which is unable to bind microtubules. Cells treated with cytochalasin D were used for analysis of cargo movement along microtubules. Strikingly, although the movement of both membranous organelles and messenger ribonucleoprotein complexes by dynein and kinesin-1 requires dynactin, the substitution of full-length p150glued with ΔN-p150glued has no effect on the rate, processivity, or step size of transport. However, truncation of the microtubule-binding domain of p150glued has a dramatic effect on cell division, resulting in the generation of multipolar spindles and free microtubule-organizing centers. Thus, dynactin binding to microtubules is required for organizing spindle microtubule arrays but not cargo motility in vivo.
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Affiliation(s)
- Hwajin Kim
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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100
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The adenomatous polyposis coli tumor suppressor protein and microtubule dynamics. CURRENT COLORECTAL CANCER REPORTS 2007. [DOI: 10.1007/s11888-007-0005-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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