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Garnett JA, Atherton J. Structure Determination of Microtubules and Pili: Past, Present, and Future Directions. Front Mol Biosci 2022; 8:830304. [PMID: 35096976 PMCID: PMC8795688 DOI: 10.3389/fmolb.2021.830304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 12/28/2021] [Indexed: 11/30/2022] Open
Abstract
Historically proteins that form highly polymeric and filamentous assemblies have been notoriously difficult to study using high resolution structural techniques. This has been due to several factors that include structural heterogeneity, their large molecular mass, and available yields. However, over the past decade we are now seeing a major shift towards atomic resolution insight and the study of more complex heterogenous samples and in situ/ex vivo examination of multi-subunit complexes. Although supported by developments in solid state nuclear magnetic resonance spectroscopy (ssNMR) and computational approaches, this has primarily been due to advances in cryogenic electron microscopy (cryo-EM). The study of eukaryotic microtubules and bacterial pili are good examples, and in this review, we will give an overview of the technical innovations that have enabled this transition and highlight the advancements that have been made for these two systems. Looking to the future we will also describe systems that remain difficult to study and where further technical breakthroughs are required.
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Affiliation(s)
- James A. Garnett
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral and Craniofacial Sciences, King’s College London, London, United Kingdom
| | - Joseph Atherton
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
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2
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Abstract
Microtubules act as "railways" for motor-driven intracellular transport, interact with accessory proteins to assemble into larger structures such as the mitotic spindle, and provide an organizational framework to the rest of the cell. Key to these functions is the fact that microtubules are "dynamic." As with actin, the polymer dynamics are driven by nucleotide hydrolysis and influenced by a host of specialized regulatory proteins, including microtubule-associated proteins. However, microtubule turnover involves a surprising behavior-termed dynamic instability-in which individual polymers switch stochastically between growth and depolymerization. Dynamic instability allows microtubules to explore intracellular space and remodel in response to intracellular and extracellular cues. Here, we review how such instability is central to the assembly of many microtubule-based structures and to the robust functioning of the microtubule cytoskeleton.
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Affiliation(s)
- Holly V Goodson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - Erin M Jonasson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
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3
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Profile of Joachim Frank, Richard Henderson, and Jacques Dubochet, 2017 Nobel Laureates in Chemistry. Proc Natl Acad Sci U S A 2017; 115:441-444. [PMID: 29196527 DOI: 10.1073/pnas.1718898114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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4
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Nogales E, Kellogg EH. Challenges and opportunities in the high-resolution cryo-EM visualization of microtubules and their binding partners. Curr Opin Struct Biol 2017. [PMID: 28628789 DOI: 10.1016/j.sbi.2017.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
As non-crystallizable polymers, microtubules have been the target of cryo-electron microscopy (cryo-EM) studies since the technique was first established. Over the years, image processing strategies have been developed that take care of the unique, pseudo-helical symmetry of the microtubule. With recent progress in data quality and data processing, cryo-EM reconstructions are now reaching resolutions that allow the generation of atomic models of microtubules and the factors that bind them. These include cellular partners that contribute to microtubule cellular functions, or small ligands that interfere with those functions in the treatment of cancer. The stage is set to generate a family portrait for all identified microtubule interacting proteins and to use cryo-EM as a drug development tool in the targeting of tubulin.
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Affiliation(s)
- Eva Nogales
- Molecular and Cell Biology Department and QB3 Institute, University of California Berkeley, CA 94720-3220, United States; Howard Hughes Medical Institute, University of California Berkeley, CA 94720-3220, United States; Molecular Biophysics and Integrative Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States.
| | - Elizabeth H Kellogg
- Molecular Biophysics and Integrative Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
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5
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Nogales E. Dear microtubule, I see you. Mol Biol Cell 2016; 27:3202-3204. [PMID: 27799495 PMCID: PMC5170852 DOI: 10.1091/mbc.e16-06-0372] [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: 11/21/2022] Open
Abstract
This essay summarizes my personal journey toward the atomic visualization of microtubules and a mechanistic understanding of how these amazing polymers work. During this journey, I have been witness and partaker in the blooming of a technique I love—cryo-electron microscopy.
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Affiliation(s)
- Eva Nogales
- Molecular and Cell Biology Department and Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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6
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Nogales E. An electron microscopy journey in the study of microtubule structure and dynamics. Protein Sci 2015; 24:1912-9. [PMID: 26401895 DOI: 10.1002/pro.2808] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/18/2015] [Accepted: 09/18/2015] [Indexed: 12/30/2022]
Abstract
Structural characterization of microtubules has been the realm of three-dimensional electron microscopy and thus has evolved hand in hand with the progress of this technique, from the initial 3D reconstructions of stained tubulin assemblies, and the first atomic model of tubulin by electron crystallography of 2D sheets of protofilaments, to the ever more detailed cryoelectron microscopy structures of frozen-hydrated microtubules. Most recently, hybrid helical and single particle image processing techniques, and the latest detector technology, have lead to atomic models built directly into the density maps of microtubules in different functional states, shading new light into the critical process of microtubule dynamic instability.
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Affiliation(s)
- Eva Nogales
- Molecular and Cell Biology Department and QB3 Institute, UC Berkeley, California, 94720.,Howard Hughes Medical Institute, UC Berkeley, California, 94720.,Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720
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7
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Cochran JC. Kinesin Motor Enzymology: Chemistry, Structure, and Physics of Nanoscale Molecular Machines. Biophys Rev 2015; 7:269-299. [PMID: 28510227 DOI: 10.1007/s12551-014-0150-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 11/16/2014] [Indexed: 11/25/2022] Open
Abstract
Molecular motors are enzymes that convert chemical potential energy into controlled kinetic energy for mechanical work inside cells. Understanding the biophysics of these motors is essential for appreciating life as well as apprehending diseases that arise from motor malfunction. This review focuses on kinesin motor enzymology with special emphasis on the literature that reports the chemistry, structure and physics of several different kinesin superfamily members.
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Affiliation(s)
- J C Cochran
- Department of Molecular & Cellular Biochemistry, Indiana University, Simon Hall Room 405C, 212 S. Hawthorne Dr., Bloomington, IN, 47405, USA.
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8
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Gonzalez MA, Cope J, Rank KC, Chen CJ, Tittmann P, Rayment I, Gilbert SP, Hoenger A. Common mechanistic themes for the powerstroke of kinesin-14 motors. J Struct Biol 2013; 184:335-44. [PMID: 24099757 PMCID: PMC3851574 DOI: 10.1016/j.jsb.2013.09.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 01/06/2023]
Abstract
Kar3Cik1 is a heterodimeric kinesin-14 from Saccharomyces cerevisiae involved in spindle formation during mitosis and karyogamy in mating cells. Kar3 represents a canonical kinesin motor domain that interacts with microtubules under the control of ATP-hydrolysis. In vivo, the localization and function of Kar3 is differentially regulated by its interacting stoichiometrically with either Cik1 or Vik1, two closely related motor homology domains that lack the nucleotide-binding site. Indeed, Vik1 structurally resembles the core of a kinesin head. Despite being closely related, Kar3Cik1 and Kar3Vik1 are each responsible for a distinct set of functions in vivo and also display different biochemical behavior in vitro. To determine a structural basis for their distinct functional abilities, we used cryo-electron microscopy and helical reconstruction to investigate the 3-D structure of Kar3Cik1 complexed to microtubules in various nucleotide states and compared our 3-D data of Kar3Cik1 with that of Kar3Vik1 and the homodimeric kinesin-14 Ncd from Drosophila melanogaster. Due to the lack of an X-ray crystal structure of the Cik1 motor homology domain, we predicted the structure of this Cik1 domain based on sequence similarity to its relatives Vik1, Kar3 and Ncd. By molecular docking into our 3-D maps, we produced a detailed near-atomic model of Kar3Cik1 complexed to microtubules in two distinct nucleotide states, a nucleotide-free state and an ATP-bound state. Our data show that despite their functional differences, heterodimeric Kar3Cik1 and Kar3Vik1 and homodimeric Ncd, all share striking structural similarities at distinct nucleotide states indicating a common mechanistic theme within the kinesin-14 family.
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Affiliation(s)
- Miguel A. Gonzalez
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Julia Cope
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Katherine C. Rank
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Chun Ju Chen
- Department of Biology and the Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Peter Tittmann
- EMEZ, Swiss Federal Institute of Technology, Hoenggerberg, 8093 Zuerich, Switzerland
| | - Ivan Rayment
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
| | - Susan P. Gilbert
- Department of Biology and the Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Andreas Hoenger
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
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9
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Behrmann E, Tao G, Stokes DL, Egelman EH, Raunser S, Penczek PA. Real-space processing of helical filaments in SPARX. J Struct Biol 2012; 177:302-13. [PMID: 22248449 DOI: 10.1016/j.jsb.2011.12.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 11/18/2022]
Abstract
We present a major revision of the iterative helical real-space refinement (IHRSR) procedure and its implementation in the SPARX single particle image processing environment. We built on over a decade of experience with IHRSR helical structure determination and we took advantage of the flexible SPARX infrastructure to arrive at an implementation that offers ease of use, flexibility in designing helical structure determination strategy, and high computational efficiency. We introduced the 3D projection matching code which now is able to work with non-cubic volumes, the geometry better suited for long helical filaments, we enhanced procedures for establishing helical symmetry parameters, and we parallelized the code using distributed memory paradigm. Additional features include a graphical user interface that facilitates entering and editing of parameters controlling the structure determination strategy of the program. In addition, we present a novel approach to detect and evaluate structural heterogeneity due to conformer mixtures that takes advantage of helical structure redundancy.
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Affiliation(s)
- Elmar Behrmann
- Max Planck Institute for Molecular Physiology, Department of Physical Biochemistry, Otto-Hahn-Straße 11, 44227 Dortmund, Germany
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10
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Cope J, Gilbert S, Rayment I, Mastronarde D, Hoenger A. Cryo-electron tomography of microtubule-kinesin motor complexes. J Struct Biol 2009; 170:257-65. [PMID: 20025975 DOI: 10.1016/j.jsb.2009.12.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Accepted: 12/03/2009] [Indexed: 01/14/2023]
Abstract
Microtubules complexed with molecular motors of the kinesin family or non-motor microtubule associated proteins (MAPs) such as tau or EB1 have been the subject of cryo-electron microcopy based 3-D studies for several years. Most of these studies that targeted complexes with intact microtubules have been carried out by helical 3-D reconstruction, while few were analyzed by single particle approaches or from 2-D crystalline arrays. Helical reconstruction of microtubule-MAP or motor complexes has been extremely successful but by definition, all helical 3-D reconstruction attempts require perfectly helical assemblies, which presents a serious limitation and confines the attempts to 15- or 16-protofilament microtubules, microtubule configurations that are very rare in nature. The rise of cryo-electron tomography within the last few years has now opened a new avenue towards solving 3-D structures of microtubule-MAP complexes that do not form helical assemblies, most importantly for the subject here, all microtubules that exhibit a lattice seam. In addition, not all motor domains or MAPs decorate the microtubule surface regularly enough to match the underlying microtubule lattice, or they adopt conformations that deviate from helical symmetry. Here we demonstrate the power and limitation of cryo-electron tomography using two kinesin motor domains, the monomeric Eg5 motor domain, and the heterodimeric Kar3Vik1 motor. We show here that tomography does not exclude the possibility of post-tomographic averaging when identical sub-volumes can be extracted from tomograms and in both cases we were able to reconstruct 3-D maps of conformations that are not possible to obtain using helical or other averaging-based methods.
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Affiliation(s)
- Julia Cope
- The Boulder Laboratory for 3-D Microscopy of Cells, University of Colorado at Boulder, Department of Molecular, Cellular, and Developmental Biology, Boulder, CO 80309-0347, USA
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11
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Ab initio reconstruction of helical samples with heterogeneity, disorder and coexisting symmetries. J Struct Biol 2009; 167:97-105. [PMID: 19447181 DOI: 10.1016/j.jsb.2009.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 05/02/2009] [Accepted: 05/07/2009] [Indexed: 01/26/2023]
Abstract
We describe modifications of the single particle helical reconstruction approach devised for the analysis of a sample that could not be processed with existing methods due to its variable and short range helical order. The added steps of reference-free two-dimensional image classification and alignment, and automated microtubule removal from images, have particular application to proteins or protein complexes that assemble around microtubules. The method was successfully applied to the Dam1 complex, an essential component of the yeast kinetochore that couples replicated chromosomes to spindle microtubules during mitosis. Because of its novel mode of binding, which does not involve a footprint on the microtubule lattice, new steps to deal with the disorder and heterogeneity of the Dam1 complex assembly were required to gain structural information about this complex both routinely and efficiently.
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12
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13
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Affiliation(s)
- Andreas Hoenger
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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14
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Neumann E, Garcia-Saez I, DeBonis S, Wade RH, Kozielski F, Conway JF. Human Kinetochore-associated Kinesin CENP-E Visualized at 17 Å Resolution Bound to Microtubules. J Mol Biol 2006; 362:203-11. [PMID: 16926026 DOI: 10.1016/j.jmb.2006.07.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 07/07/2006] [Accepted: 07/20/2006] [Indexed: 11/23/2022]
Abstract
The highly dynamic process of cell division is effected, in part, by molecular motors that generate the forces necessary for its enactment. Several members of the kinesin superfamily of motor proteins are implicated in mitosis, such as CENP-E, which plays essential roles in cell division, including association with the kinetochore to stabilize attachment of chromosomes to microtubules prior to and during their separation. Neither the functional assembly state of CENP-E nor its direction of motion along the polar microtubule are certain. To determine the mode of interaction between CENP-E and microtubules, we have used cryo-electron microscopy to visualize CENP-E motor domains complexed with microtubules and calculated a density map of the complex to 17 A resolution by combining helical and single-particle reconstruction methods. The interface between the motor domain and microtubules was modeled by docking atomic-resolution models of the subunits into the cryoEM density map. Our results support a plus end motion for CENP-E, consistent with features of the crystallographic structure. Despite considerable functional differences from the monomeric transporter kinesin KIF1A and the oppositely directed ncd kinesin, CENP-E appears to share many features of the intermolecular interactions, suggesting that differences in motor function are governed by small variations in the loops at the microtubule interface.
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Affiliation(s)
- E Neumann
- Laboratoire de Microscopie Electronique Structurale, Institut de Biologie Structurale J.-P. Ebel, UMR 5075 CNRS-CEA-UJF, 38027 Grenoble, France
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15
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Hizlan D, Mishima M, Tittmann P, Gross H, Glotzer M, Hoenger A. Structural analysis of the ZEN-4/CeMKLP1 motor domain and its interaction with microtubules. J Struct Biol 2006; 153:73-84. [PMID: 16361109 DOI: 10.1016/j.jsb.2005.10.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 10/17/2005] [Accepted: 10/27/2005] [Indexed: 11/25/2022]
Abstract
The centralspindlin complex is required for the assembly and maintenance of the central spindle during late anaphase and the completion of cytokinesis. It is composed of two copies each of the kinesin-like protein ZEN-4, a Caenorhabditis elegans MKLP-1 (Kinesin-6 family), and the RhoGAP CYK-4. By using cryo-electron microscopy and helical 3D reconstruction, we are investigating the structural features of the interactions between monomeric and dimeric motor domain constructs of ZEN-4 and microtubules. We have calculated helically averaged 3D maps of microtubules decorated with ZEN-4 motor domain in the presence of AMP-PNP, ADP, ADP-AlF(4)(-), and nucleotide-free conditions. We used statistical difference mapping to compare these maps among each other and to related maps obtained from microtubules decorated with a well-characterized Kinesin-1 motor domain from Neurospora crassa. Thereby, we found distinct structural features in microtubule-ZEN-4 complexes that may directly relate to the functional properties of ZEN-4 and centralspindlin. Furthermore, we investigated the location, structure, and function of a highly conserved extension of approximately 50 residues unique to the Kinesin-6 subfamily, located in the motor core loop6/beta4 region.
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Affiliation(s)
- Dilem Hizlan
- European Molecular Biology Laboratory, Structural Biology and Biocomputing Programme, Heidelberg, Germany
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16
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Endres NF, Yoshioka C, Milligan RA, Vale RD. A lever-arm rotation drives motility of the minus-end-directed kinesin Ncd. Nature 2005; 439:875-8. [PMID: 16382238 PMCID: PMC2851630 DOI: 10.1038/nature04320] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Accepted: 09/23/2005] [Indexed: 11/08/2022]
Abstract
Kinesins are microtubule-based motor proteins that power intracellular transport. Most kinesin motors, exemplified by Kinesin-1, move towards the microtubule plus end, and the structural changes that govern this directional preference have been described. By contrast, the nature and timing of the structural changes underlying the minus-end-directed motility of Kinesin-14 motors (such as Drosophila Ncd) are less well understood. Using cryo-electron microscopy, here we demonstrate that a coiled-coil mechanical element of microtubule-bound Ncd rotates approximately 70 degrees towards the minus end upon ATP binding. Extending or shortening this coiled coil increases or decreases velocity, respectively, without affecting ATPase activity. An unusual Ncd mutant that lacks directional preference shows unstable nucleotide-dependent conformations of its coiled coil, underscoring the role of this mechanical element in motility. These results show that the force-producing conformational change in Ncd occurs on ATP binding, as in other kinesins, but involves the swing of a lever-arm mechanical element similar to that described for myosins.
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Affiliation(s)
- Nicholas F Endres
- The Howard Hughes Medical Institute, and the Department of Cellular and Molecular Pharmacology, University of California San Francisco, 600 16th Street, San Francisco, California 94107, USA
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17
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Marx A, Müller J, Mandelkow EM, Hoenger A, Mandelkow E. Interaction of kinesin motors, microtubules, and MAPs. J Muscle Res Cell Motil 2005; 27:125-37. [PMID: 16362723 DOI: 10.1007/s10974-005-9051-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Accepted: 11/18/2005] [Indexed: 11/30/2022]
Abstract
Kinesins are a family of microtubule-dependent motor proteins that carry cargoes such as vesicles, organelles, or protein complexes along microtubules. Here we summarize structural studies of the "conventional" motor protein kinesin-1 and its interactions with microtubules, as determined by X-ray crystallography and cryo-electron microscopy. In particular, we consider the docking between the kinesin motor domain and tubulin subunits and summarize the evidence that kinesin binds mainly to beta tubulin with the switch-2 helix close to the intradimer interface between alpha and beta tubulin.
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Affiliation(s)
- A Marx
- Max-Planck-Unit for Structural Molecular Biology, Notkestrasse 85, 22607, Hamburg, Germany
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18
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Asenjo AB, Krohn N, Sosa H. Configuration of the two kinesin motor domains during ATP hydrolysis. Nat Struct Mol Biol 2003; 10:836-42. [PMID: 12970755 DOI: 10.1038/nsb984] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2003] [Accepted: 07/24/2003] [Indexed: 11/08/2022]
Abstract
To understand the mechanism of kinesin movement we have investigated the relative configuration of the two kinesin motor domains during ATP hydrolysis using fluorescence polarization microscopy of ensemble and single molecules. We found that: (i) in nucleotide states that induce strong microtubule binding, both motor domains are bound to the microtubule with similar orientations; (ii) this orientation is maintained during processive motion in the presence of ATP; (iii) the neck-linker region of the motor domain has distinct configurations for each nucleotide condition tested. Our results fit well with a hand-over-hand type movement mechanism and suggest how the ATPase cycle in the two motor domains is coordinated. We propose that the motor neck-linker domain configuration controls ADP release.
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Affiliation(s)
- Ana B Asenjo
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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19
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Skiniotis G, Surrey T, Altmann S, Gross H, Song YH, Mandelkow E, Hoenger A. Nucleotide-induced conformations in the neck region of dimeric kinesin. EMBO J 2003; 22:1518-28. [PMID: 12660159 PMCID: PMC152908 DOI: 10.1093/emboj/cdg164] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The neck region of kinesin constitutes a key component in the enzyme's walking mechanism. Here we applied cryoelectron microscopy and image reconstruction to investigate the location of the kinesin neck in dimeric and monomeric constructs complexed to microtubules. To this end we enhanced the visibility of this region by engineering an SH3 domain into the transition between neck linker and neck coiled coil. The resulting chimeric kinesin constructs remained functional as verified by physiology assays. In the presence of AMP-PNP the SH3 domains allowed us to identify the position of the neck in a well defined conformation and revealed its high flexibility in the absence of nucleotide. We show here the double-headed binding of dimeric kinesin along the same protofilament, which is characterized by the opposite directionality of neck linkers. In this configuration the neck coiled coil appears fully zipped. The position of the neck region in dimeric constructs is not affected by the presence of the tubulin C-termini as confirmed by subtilisin treatment of microtubules prior to motor decoration.
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Affiliation(s)
- Georgios Skiniotis
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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20
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Abstract
We have obtained a 3D reconstruction of intact microtubules, using cryoelectron microscopy and image processing, at a resolution of about 8 A, sufficient to resolve much of the secondary structure. The level of detail in the map allows docking of the tubulin structure previously determined by electron crystallography, with very strong constraints, providing several important insights not previously available through docking tubulin into lower-resolution maps. This work provides an improved picture of the interactions between adjacent protofilaments, which are responsible for microtubule stability, and also suggests that some structural features are different in microtubules from those in the zinc sheets with which the tubulin structure was determined.
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Affiliation(s)
- Huilin Li
- Life Sciences Division, Lawrence Berkeley National Laboratory, CA 94720, USA
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21
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Noël C, Gerbod D, Fast NM, Wintjens R, Delgado-Viscogliosi P, Doolittle WF, Viscogliosi E. Tubulins in Trichomonas vaginalis: molecular characterization of alpha-tubulin genes, posttranslational modifications, and homology modeling of the tubulin dimer. J Eukaryot Microbiol 2001; 48:647-54. [PMID: 11831773 DOI: 10.1111/j.1550-7408.2001.tb00204.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We have isolated and analysed an alpha-tubulin-encoding gene (atub1) in an early-diverging eukaryote, Trichomonas vaginalis. The complete atub1 open reading frame included 1.356 bp encoding a polypeptide of 452 amino-acyl residues. A second alpha-tubulin gene (atub2) was amplified by PCR using primers derived from consensus alpha-tubulin amino acid sequences. Both T. vaginalis alpha-tubulin sequences showed high identity to those described in other parabasalids (94.4%-97.3%), and exhibited a high degree of similarity to sequences from Metazoa (such as pig brain) and diplomonads (such as Giardia). Despite large evolutionary distances previously observed between trichomonads and mammals, the three-dimensional model of the T. vaginalis tubulin dimer was very similar to that of pig brain. Possible correlations between alpha-tubulin sequences and posttranslational modifications (PTMs) were examined. Our observations corroborated previous data obtained in T. vaginalis using specific anti-PTMs antibodies. As described in the related species Tritrichomonas mobilensis, microtubules are likely acetylated, non-tyrosinated, glutamylated, and non-glycylated in T. vaginalis. Evolutionary considerations concerning the time of appearance of these tubulin PTMs are also discussed since trichomonads are potentially one of the earliest diverging eukaryotic lineages.
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Affiliation(s)
- C Noël
- Institut Pasteur, INSERM U547, Lille, France
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22
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Peterman EJ, Sosa H, Goldstein LS, Moerner WE. Polarized fluorescence microscopy of individual and many kinesin motors bound to axonemal microtubules. Biophys J 2001; 81:2851-63. [PMID: 11606296 PMCID: PMC1301750 DOI: 10.1016/s0006-3495(01)75926-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Kinesin is a molecular motor that interacts with microtubules and uses the energy of ATP hydrolysis to produce force and movement in cells. To investigate the conformational changes associated with this mechanochemical energy conversion, we developed a fluorescence polarization microscope that allows us to obtain information on the orientation of single as well as many fluorophores. We attached either monofunctional or bifunctional fluorescent probes to the kinesin motor domain. Both types of labeled kinesins show anisotropic fluorescence signals when bound to axonemal microtubules, but the bifunctional probe is less mobile resulting in higher anisotropy. From the polarization experiments with the bifunctional probe, we determined the orientation of kinesin bound to microtubules in the presence of AMP-PNP and found close agreement with previous models derived from cryo-electron microscopy. We also compared the polarization anisotropy of monomeric and dimeric kinesin constructs bound to microtubules in the presence of AMP-PNP. Our results support models of mechanochemistry that require a state in which both motor domains of a kinesin dimer bind simultaneously with similar orientation with respect to the microtubule.
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Affiliation(s)
- E J Peterman
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
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23
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Vilfan A, Frey E, Schwabl F, Thormählen M, Song YH, Mandelkow E. Dynamics and cooperativity of microtubule decoration by the motor protein kinesin. J Mol Biol 2001; 312:1011-26. [PMID: 11580246 DOI: 10.1006/jmbi.2001.5020] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a theoretical and experimental analysis of the interaction between microtubules and dimeric motor proteins (kinesin, NCD), with special emphasis on the stoichiometry of the interaction, cooperative effects, and their consequences for the interpretation of biochemical and image reconstruction results. Monomeric motors can bind equivalently to microtubules without interference, at a stoichiometry of one motor head per tubulin subunit (alphabeta-heterodimer). By contrast, dimeric motors can interact with stoichiometries ranging between one and two heads per tubulin subunit, depending on binding constants of the first head and the subsequent binding of the second head, and the concentration of dimers in solution. Further, we show that an attractive interaction between the bound motor molecules can explain the higher periodicities observed in decorated microtubules (e.g. 16 nm periodicity), and the non-uniform decoration of a population of microtubules and give an estimate of the strength of this interaction.
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Affiliation(s)
- A Vilfan
- Institut für Theoretische Physik, Technische Universität München, James-Franck-Strasse, Garching, 85747, Germany.
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24
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Svergun DI, Zaccai G, Malfois M, Wade RH, Koch MH, Kozielski F. Conformation of the Drosophila motor protein non-claret disjunctional in solution from X-ray and neutron scattering. J Biol Chem 2001; 276:24826-32. [PMID: 11335729 DOI: 10.1074/jbc.m103618200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The quaternary structures of monomeric and dimeric Drosophila non-claret disjunctional (ncd) constructs were investigated using synchrotron x-ray and neutron solution scattering, and their low resolution shapes were restored ab initio from the scattering data. The experimental curves were further compared with those computed from crystallographic models of one monomeric and three available dimeric ncd structures in the microtubule-independent ADP-bound state. These comparisons indicate that accounting for the missing parts in the crystal structures for all these constructs is indispensable to obtain reasonable fits to the scattering patterns. A ncd construct (MC6) lacking the coiled-coil region is monomeric in solution, but the calculated scattering from the crystallographic monomer yields a poor fit to the data. A tentative configuration of the missing C-terminal residues in the form of an antiparallel beta-sheet was found that significantly improves the fit. The atomic model of a short dimeric ncd construct (MC5) without 2-fold symmetry is found to fit the data better than the symmetric models. Addition of the C-terminal residues to both head domains gives an excellent fit to the x-ray and neutron experimental data, although the orientation of the beta-sheet differs from that of the monomer. The solution structure of the long ncd construct (MC1) including complete N-terminal coiled-coil and motor domains is modeled by adding a straight coiled-coil section to the model of MC5.
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Affiliation(s)
- D I Svergun
- Institute of Crystallography, Russian Academy of Sciences, Leninsky Prospekt 59, 117333 Russia.
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25
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Abstract
Ncd is a kinesin-related protein that drives movement to the minus-end of microtubules. Pre-steady-state kinetic experiments have been employed to investigate the cooperative interactions between the motor domains of the MC1 dimer and to establish the ATPase mechanism. Our results indicate that the active sites of dimeric Ncd free in solution are not equivalent; ADP is held more tightly at one site than at the other. Upon microtubule binding, fast release of ADP from the first motor domain is stimulated at 18 s(-1), yet rate-limiting ADP release from the second motor domain occurs at 1.4 s(-1). We propose that the head with the low affinity for ADP binds the microtubule first to establish the directional bias of the microtubule.Ncd intermediate where one motor domain is bound to the microtubule with the second head detached and directed toward the minus-end of the microtubule. The force generating cycle is initiated as ATP binds to the empty site of the microtubule-bound head. ATP hydrolysis at head 1 is required for head 2 to bind to the microtubule. The kinetics indicate that two ATP molecules are required for a single step and force generation for minus-end directed movement generated by this non-processive dimeric motor.
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Affiliation(s)
- K A Foster
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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26
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Kinosita K. Linear and rotary molecular motors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2001; 453:5-13; discussion 13-4. [PMID: 9889809 DOI: 10.1007/978-1-4684-6039-1_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A single molecule of F1-ATPase has been shown to be the smallest rotary motor ever found, with a central rotor of radius approximately 1 nm turning in a stator barrel of radius approximately 5 nm. Continuous rotation of the central gamma subunit was revealed under an optical microscope by attaching to gamma a huge marker, an actin filament. In a separate study, rotation of a sliding actin filament around its axis has been revealed by attaching a small probe, a single fluorescent dye molecule, to the actin filament and detecting the orientation of the fluorophore, and thus of the actin filament, through polarization imaging. The axial rotation was slow compared to the linear sliding, indicating that myosin does not 'walk' along the helical array of actin protomers but 'runs,' skipping many protomers. The two motors above, one rotary and the other linear, represent two extreme cases of the mode of motor operation: in the F1-ATPase the two partners, the rotor and stator, never detach from each other whereas myosin touches actin only occasionally. In considering the mechanisms of these and other molecular motors, distinction between bending and binding is important. The use of huge and small probes as described above should be useful in studies of protein machines in general, as a means of detecting conformational changes in a single protein molecule during function.
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Affiliation(s)
- K Kinosita
- Department of Physics, Faculty of Science and Technology, Keio University, Yokohama, Japan
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27
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Downing KH. Structural basis for the interaction of tubulin with proteins and drugs that affect microtubule dynamics. Annu Rev Cell Dev Biol 2001; 16:89-111. [PMID: 11031231 DOI: 10.1146/annurev.cellbio.16.1.89] [Citation(s) in RCA: 272] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The microtubule cytoskeleton is a highly regulated system. At different times in the cell cycle and positions within the organism, microtubules can be very stable or highly dynamic. Stability and dynamics are regulated by interaction with a large number of proteins that themselves may change at specific points in the cell cycle. Exogenous ligands can disrupt the normal processes by either increasing or decreasing microtubule stability and inhibiting their dynamic behavior. The recent determination of the structure of tubulin, the main component of microtubules, makes it possible now to begin to understand the details of these interactions. We review here the structure of the tubulin dimer, with particular regard to how proteins and drugs may bind and modulate microtubule dynamics.
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Affiliation(s)
- K H Downing
- Donner Laboratory, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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28
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Abstract
Members of the kinesin superfamily of microtubule-based motors and the myosin superfamily of actin-based motors that move 'backwards' have been identified. As the core catalytic domains of myosins and kinesins are similar in structure, this raises the intriguing questions of how direction reversal is accomplished and whether kinesins and myosins share mechanisms for switching their motors into reverse.
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Affiliation(s)
- T Hasson
- Section of Cell and Developmental Biology, Division of Biology, University of California, San Diego, La Jolla, California 92093-0368, USA.
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29
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deCastro MJ, Fondecave RM, Clarke LA, Schmidt CF, Stewart RJ. Working strokes by single molecules of the kinesin-related microtubule motor ncd. Nat Cell Biol 2000; 2:724-9. [PMID: 11025663 DOI: 10.1038/35036357] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ncd protein is a dimeric, ATP-powered motor that belongs to the kinesin family of microtubule motor proteins. Here we resolve single mechanochemical cycles of recombinant, dimeric, full-length ncd, using optical-tweezers-based instrumentation and a three-bead, suspended-microtubule assay. Under conditions of limiting ATP, isolated and transient microtubule-binding events exhibit exponentially distributed and ATP-concentration-dependent lifetimes. These events do not involve consecutive steps along the microtubule, quantitatively confirming that ncd is non-processive. At low loads, a single motor molecule produces ATP-triggered working strokes of about 9 nm, which occur at the ends of binding events.
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Affiliation(s)
- M J deCastro
- Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112, USA
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30
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Hoenger A, Doerhoefer M, Woehlke G, Tittmann P, Gross H, Song YH, Mandelkow E. Surface topography of microtubule walls decorated with monomeric and dimeric kinesin constructs. Biol Chem 2000; 381:1001-11. [PMID: 11076033 DOI: 10.1515/bc.2000.123] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The surface topography of opened-up microtubule walls (sheets) decorated with monomeric and dimeric kinesin motor domains was investigated by freeze-drying and unidirectional metal shadowing. Electron microscopy of surface-shadowed specimens produces images with a high signal/noise ratio, which enable a direct observation of surface features below 2 nm detail. Here we investigate the inner and outer surface of microtubules and tubulin sheets with and without decoration by kinesin motor domains. Tubulin sheets are flattened walls of microtubules, keeping lateral protofilament contacts intact. Surface shadowing reveals the following features: (i) when the microtubule outside is exposed the surface relief is dominated by the bound motor domains. Monomeric motor constructs generate a strong 8 nm periodicity, corresponding to the binding of one motor domain per alpha-beta-tubulin heterodimer. This surface periodicity largely disappears when dimeric kinesin motor domains are used for decoration, even though it is still visible in negatively stained or frozen hydrated specimens. This could be explained by disorder in the binding of the second (loosely tethered) kinesin head, and/or disorder in the coiled-coil tail. (ii) Both surfaces of undecorated sheets or microtubules, as well as the inner surface of decorated sheets, reveal a strong 4 nm repeat (due to the periodicity of tubulin monomers) and a weak 8 nm repeat (due to slight differences between alpha- and beta-tubulin). The differences between alpha- and beta-tubulin on the inner surface are stronger than expected from cryo-electron microscopy of unstained microtubules, indicating the existence of tubulin subdomain-specific surface properties that reflect the surface corrugation and hence metal deposition during evaporation. The 16 nm periodicity visible in some negatively stained specimens (caused by the pairing of cooperatively bound kinesin dimers) is not detected by surface shadowing.
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Affiliation(s)
- A Hoenger
- European Molecular Biology Laboratory, Heidelberg, Germany
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31
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Sosa H, Chrétien D. Relationship between moiré patterns, tubulin shape, and microtubule polarity. CELL MOTILITY AND THE CYTOSKELETON 2000; 40:38-43. [PMID: 9605970 DOI: 10.1002/(sici)1097-0169(1998)40:1<38::aid-cm4>3.0.co;2-b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The polarity of microtubules is reflected in cryo-electron microscope images and in three-dimensional reconstructions [Chrétien et al., 1996: Structure 4:1031-1040; Sosa and Milligan, 1996: J. Mol. Biol. 260:743-755]. This paper shows how the directionality of the moiré patterns and the shape of the tubulin subunits are related. Microtubules observed by cryo-electron microscopy show an arrowhead moiré pattern that points toward the plus end of microtubules with a right-handed protofilament skew and toward the minus end of microtubules with a left-handed protofilament skew. On the other hand, three-dimensional reconstructions of microtubules observed from the plus end reveal a radial counterclockwise slew of the tubulin subunits. We show how these polar features are related and present unambiguous rules for determining the polarity on longitudinal and axial views of microtubules.
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Affiliation(s)
- H Sosa
- Department of Cell Biology MB25, The Scripps Research Institute, La Jolla, California, USA
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32
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Wade RH, Kozielski F. Structural links to kinesin directionality and movement. NATURE STRUCTURAL BIOLOGY 2000; 7:456-60. [PMID: 10881190 DOI: 10.1038/75850] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The kinesin motor proteins generate directional movement along microtubules and are involved in many vital processes, including cell division, in eukaryotes. The kinesin superfamily is characterized by a conserved motor domain of approximately 320 residues. Dimeric constructs of N and C class kinesins, with the motor domains at opposite ends of the heavy chain, move towards microtubule plus and minus ends, respectively. Their crystal structures differ mainly in the region linking the motor domain core to the alpha-helical coiled coil dimerization domain. Chimeric kinesins show that regions outside of the motor domain core determine the direction of movement and mutations in the linker region have a strong effect on motility. Recent work on chimeras and mutants is discussed in a structural context giving insights to possible molecular mechanisms of kinesin directionality and motility.
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Affiliation(s)
- R H Wade
- Institut de Biologie Structurale (CEA & CNRS), Grenoble, France.
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33
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Chrétien D, Fuller SD. Microtubules switch occasionally into unfavorable configurations during elongation. J Mol Biol 2000; 298:663-76. [PMID: 10788328 DOI: 10.1006/jmbi.2000.3696] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tubulin assembles to form a range of structures that differ by their protofilament and monomer helix-start numbers. The microtubule lattice is believed to accommodate these different configurations by skewing the protofilaments so that the lateral interactions between tubulin subunits are maintained. Here, we present the characterization of 14 types of microtubules, including six novel ones, through an extensive analysis of microtubules assembled in vitro from pure tubulin. Although the six new types represented only 1 % of the total length of the population examined ( approximately 17 mm), they define the limits of microtubule structure and assembly. Protofilament skewing is restricted to within +/-2 degrees. Outside this range, the restoring force induced by the skewed protofilaments is compensated by a longitudinal shift (less than +/-0.2 nm) between adjacent protofilaments. Configurations with theoretical protofilament skew angles larger than +/-4 degrees or that necessitate larger modifications of the microtubule surface lattice were not observed. Analysis of the microtubule types distribution reveals that it is sharply peaked around the less skewed conformations. These results indicate that both the flexibility of the protofilaments and the strength of their lateral interactions restrict the range of structures assembled. They also demonstrate that growing microtubules can occasionally switch into energetically unfavorable configurations, a behavior that may account for the stochastic nature of catastrophes.
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Affiliation(s)
- D Chrétien
- Equipe ATIPE, UPRES-A 6026 CNRS, Université de Rennes 1, Campus de Beaulieu Bt 13, Rennes, 35042, France.
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34
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Hoenger A, Thormählen M, Diaz-Avalos R, Doerhoefer M, Goldie KN, Müller J, Mandelkow E. A new look at the microtubule binding patterns of dimeric kinesins. J Mol Biol 2000; 297:1087-103. [PMID: 10764575 DOI: 10.1006/jmbi.2000.3627] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interactions of monomeric and dimeric kinesin and ncd constructs with microtubules have been investigated using cryo-electron microscopy (cryo-EM) and several biochemical methods. There is a good consensus on the structure of dimeric ncd when bound to a tubulin dimer showing one head attached directly to tubulin, and the second head tethered to the first. However, the 3D maps of dimeric kinesin motor domains are still quite controversial and leave room for different interpretations. Here we reinvestigated the microtubule binding patterns of dimeric kinesins by cryo-EM and digital 3D reconstruction under different nucleotide conditions and different motor:tubulin ratios, and determined the molecular mass of motor-tubulin complexes by STEM. Both methods revealed complementary results. We found that the ratio of bound kinesin motor-heads to alphabeta-tubulin dimers was never reaching above 1.5 irrespective of the initial mixing ratios. It appears that each kinesin dimer occupies two microtubule-binding sites, provided that there is a free one nearby. Thus the appearances of different image reconstructions can be explained by non-specific excess binding of motor heads. Consequently, the use of different apparent density distributions for docking the X-ray structures onto the microtubule surface leads to different and mutually exclusive models. We propose that in conditions of stoichiometric binding the two heads of a kinesin dimer separate and bind to different tubulin subunits. This is in contrast to ncd where the two heads remain tightly attached on the microtubule surface. Using dimeric kinesin molecules crosslinked in their neck domain we also found that they stabilize protofilaments axially, but not laterally, which is a strong indication that the two heads of the dimers bind along one protofilament, rather than laterally bridging two protofilaments. A molecular walking model based on these results summarizes our conclusions and illustrates the implications of symmetry for such models.
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Affiliation(s)
- A Hoenger
- Structure Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg, D-69117, Germany.
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35
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Woehlke G, Schliwa M. Directional motility of kinesin motor proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1496:117-27. [PMID: 10722881 DOI: 10.1016/s0167-4889(00)00013-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Kinesin motor proteins are molecules capable of moving along microtubules. They share homology in the so-called core motor domain which acts as a microtubule-dependent ATPase. The surprising finding that different members of the superfamily move in opposite directions along microtubules despite their close similarity has stimulated intensive research on the determinants of motor directionality. This article reviews recent biophysical, biochemical, structural and mutagenic studies that contributed to the elucidation of the mechanisms that cause directional motion of kinesin motor proteins.
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Affiliation(s)
- G Woehlke
- Adolf-Butenandt-Institute of Cell Biology, Ludwig-Maximilians-University Munich, Schillerstr. 42, D-80 336, Munich, Germany.
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36
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Abstract
Atomic resolution three-dimensional structures of two oppositely directed kinesin motors - conventional kinesin and non-claret disjunctional (ncd) protein - are now available in their functional dimeric form. A detailed model of the microtubule has also been recently obtained by docking the 3.7 A structure of tubulin into a 20 A map of the microtubule. Recent structural studies of kinesin motors and their microtubule tracks are contributing to our current understanding of kinesin motor mechanisms.
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Affiliation(s)
- E P Sablin
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143, USA.
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37
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Smyczynski C, Derancourt J, Chaussepied P. Regulation of ncd by the oligomeric state of tubulin. J Mol Biol 2000; 295:325-36. [PMID: 10623529 DOI: 10.1006/jmbi.1999.3356] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have compared the interaction of ncd (non-claret disjunctional), a kinesin related protein, with microtubules and tubulin heterodimer. Ultracentrifugation experiments revealed that the ncd motor domain, residues 335-700 (ncd335), does not induce tubulin polymerization but stabilizes pre-formed microtubules with a maximum effect at a 1:1 ncd335:tubulin ratio. Ncd335 binding to tubulin or microtubules was estimated by following the change in fluorescence polarization of an exogenous dye attached to Cys670 of ncd335. Ncd335 binding to tubulin (containing GTP or GDP-bound) is characterized by a 2:1 stoichiometry, a higher affinity and an increased sensitivity towards salt, ADP, ATP and AMPPNP, as compared with ncd335 binding to microtubules. Maximum ATPases were 0.06-0.08 sec(-1) and 1.8-2.0 sec(-1) for the ncd335-tubulin and ncd335-microtubules complexes, respectively. Only the polymerized complex is fully functional, suggesting the presence of additional contacts between adjacent protofilaments. Moreover, the data reveal that the oligomeric state of microtubules is a potent regulator for the activity of kinesin related proteins.
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Affiliation(s)
- C Smyczynski
- CRBM du CNRS, IFR 24, Montpellier C¿edex 05, 34293, France
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38
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Kozielski F, De Bonis S, Burmeister WP, Cohen-Addad C, Wade RH. The crystal structure of the minus-end-directed microtubule motor protein ncd reveals variable dimer conformations. Structure 1999; 7:1407-16. [PMID: 10574799 DOI: 10.1016/s0969-2126(00)80030-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The kinesin superfamily of microtubule-associated motor proteins are important for intracellular transport and for cell division in eukaryotes. Conventional kinesins have the motor domain at the N terminus of the heavy chain and move towards the plus end of microtubules. The ncd protein is necessary for chromosome segregation in meiosis. It belongs to a subfamily of kinesins that have the motor domain at the C terminus and move towards the minus end of microtubules. RESULTS The crystal structure of dimeric ncd has been obtained at 2.9 A resolution from crystals with the C222(1) space group, with two independent dimers per asymmetric unit. The motor domains in these dimers are not related by crystallographic symmetry and the two ncd dimers have significantly different conformations. An alpha-helical coiled coil connects, and interacts with, the motor domains. CONCLUSIONS The ncd protein has a very compact structure, largely due to extended interactions of the coiled coil with the head domains. Despite this, we find that the overall conformation of the ncd dimer can be rotated by as much as 10 degrees away from that of the twofold-symmetric archetypal ncd. The crystal structures of conventional kinesin and of ncd suggest a structural rationale for the reversal of the direction of movement in chimeric kinesins.
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Affiliation(s)
- F Kozielski
- Institut de Biologie Structurale (CEA/CNRS), Grenoble, 38027, France
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39
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Abstract
Work over the past two years has led to a breakthrough in our understanding of the molecular basis of the directionality of the kinesin motor proteins. This breakthrough has come first from the reversal of directionality of the kinesin-related motor Ncd, followed closely by the reversal of kinesin's directionality and the finding that the Ncd 'neck' can convert Ncd or kinesin, which are intrinsically plus-end-directed microtubule motors, into a minus-end motor. These findings raise several outstanding questions, foremost, how does the neck function in motor directionality?
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Affiliation(s)
- S A Endow
- Department of Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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40
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Hirose K, Löwe J, Alonso M, Cross RA, Amos LA. Congruent docking of dimeric kinesin and ncd into three-dimensional electron cryomicroscopy maps of microtubule-motor ADP complexes. Mol Biol Cell 1999; 10:2063-74. [PMID: 10359615 PMCID: PMC25414 DOI: 10.1091/mbc.10.6.2063] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We present a new map showing dimeric kinesin bound to microtubules in the presence of ADP that was obtained by electron cryomicroscopy and image reconstruction. The directly bound monomer (first head) shows a different conformation from one in the more tightly bound empty state. This change in the first head is amplified as a movement of the second (tethered) head, which tilts upward. The atomic coordinates of kinesin.ADP dock into our map so that the tethered head associates with the bound head as in the kinesin dimer structure seen by x-ray crystallography. The new docking orientation avoids problems associated with previous predictions; it puts residues implicated by proteolysis-protection and mutagenesis studies near the microtubule but does not lead to steric interference between the coiled-coil tail and the microtubule surface. The observed conformational changes in the tightly bound states would probably bring some important residues closer to tubulin. As expected from the homology with kinesin, the atomic coordinates of nonclaret disjunctional protein (ncd).ADP dock in the same orientation into the attached head in a map of microtubules decorated with dimeric ncd.ADP. Our results support the idea that the observed direct interaction between the two heads is important at some stages of the mechanism by which kinesin moves processively along microtubules.
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Affiliation(s)
- K Hirose
- National Institute of Advanced Interdisciplinary Research, Higashi, Tsukuba 305-8562, Japan
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41
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Manning BD, Barrett JG, Wallace JA, Granok H, Snyder M. Differential regulation of the Kar3p kinesin-related protein by two associated proteins, Cik1p and Vik1p. J Cell Biol 1999; 144:1219-33. [PMID: 10087265 PMCID: PMC2150581 DOI: 10.1083/jcb.144.6.1219] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanisms by which kinesin-related proteins interact with other proteins to carry out specific cellular processes is poorly understood. The kinesin-related protein, Kar3p, has been implicated in many microtubule functions in yeast. Some of these functions require interaction with the Cik1 protein (Page, B.D., L.L. Satterwhite, M.D. Rose, and M. Snyder. 1994. J. Cell Biol. 124:507-519). We have identified a Saccharomyces cerevisiae gene, named VIK1, encoding a protein with sequence and structural similarity to Cik1p. The Vik1 protein is detected in vegetatively growing cells but not in mating pheromone-treated cells. Vik1p physically associates with Kar3p in a complex separate from that of the Kar3p-Cik1p complex. Vik1p localizes to the spindle-pole body region in a Kar3p-dependent manner. Reciprocally, concentration of Kar3p at the spindle poles during vegetative growth requires the presence of Vik1p, but not Cik1p. Phenotypic analysis suggests that Cik1p and Vik1p are involved in different Kar3p functions. Disruption of VIK1 causes increased resistance to the microtubule depolymerizing drug benomyl and partially suppresses growth defects of cik1Delta mutants. The vik1Delta and kar3Delta mutations, but not cik1Delta, partially suppresses the temperature-sensitive growth defect of strains lacking the function of two other yeast kinesin-related proteins, Cin8p and Kip1p. Our results indicate that Kar3p forms functionally distinct complexes with Cik1p and Vik1p to participate in different microtubule-mediated events within the same cell.
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Affiliation(s)
- B D Manning
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
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42
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Abstract
Several X-ray crystal structures of kinesin motor domains have recently been solved at high resolution ( approximately 0.2-0.3 nm), in both their monomeric and dimeric states. They show the folding of the polypeptide chain and different arrangements of subunits in the dimer. In addition, cryo-electron microscopy and image reconstruction have revealed microtubules decorated with kinesin at intermediate resolution ( approximately 2 nm), showing the distribution and orientation of kinesin heads on the microtubule surface. The comparison of the X-ray and electron microscopy results yields a model of how monomeric motor domains bind to the microtubule but the binding of dimeric motors, their stoichiometry, or the influence of nucleotides remains a matter of debate.
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Affiliation(s)
- E Mandelkow
- Max-Planck-Unit for Structural Molecular Biology Notkestrasse 85 D-22607 Hamburg Germany.
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43
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Abstract
A high-resolution model of the microtubule has been obtained by docking the crystal structure of tubulin into a 20 A map of the microtubule. The excellent fit indicates the similarity of the tubulin conformation in both polymers and defines the orientation of the tubulin structure within the microtubule. Long C-terminal helices form the crest on the outside of the protofilament, while long loops define the microtubule lumen. The exchangeable nucleotide in beta-tubulin is exposed at the plus end of the microtubule, while the proposed catalytic residue in alpha-tubulin is exposed at the minus end. Extensive longitudinal interfaces between monomers have polar and hydrophobic components. At the lateral contacts, a nucleotide-sensitive helix interacts with a loop that contributes to the binding site of taxol in beta-tubulin.
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Affiliation(s)
- E Nogales
- Lawrence Berkeley National Laboratory, Molecular and Cell Biology Department, University of California at Berkeley, California 94720, USA.
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44
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Foster KA, Correia JJ, Gilbert SP. Equilibrium binding studies of non-claret disjunctional protein (Ncd) reveal cooperative interactions between the motor domains. J Biol Chem 1998; 273:35307-18. [PMID: 9857072 DOI: 10.1074/jbc.273.52.35307] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-claret disjunctional protein (Ncd) is a minus end-directed microtubule motor required for normal spindle assembly and integrity during Drosophila oogenesis. We have pursued equilibrium binding experiments to examine the affinity of Ncd for microtubules in the presence of the ATP nonhydrolyzable analog 5'-adenylyl-beta, gamma-imidodiphosphate (AMP-PNP), ADP, or ADP + Pi using both dimeric (MC1) and monomeric (MC6) Ncd constructs expressed in Escherichia coli. Both MC1 and MC6 sediment with microtubules in the absence of added nucleotide as well as in the presence of either ADP or AMP-PNP. Yet, in the presence of ADP + Pi, there is a decrease in the affinity of both MC1 and MC6 for microtubules. The data for dimeric MC1 show that release of the dimer to the supernatant is sigmoidal with the apparent Kd(Pi) for the two phosphate sites at 23.3 and 1.9 mM, respectively. The results indicate that binding at the first phosphate site enhances binding at the second site, thus cooperatively stimulating release. Stopped-flow kinetics indicate that MgATP promotes dissociation of the Mt.MC1 complex at 14 s-1, yet AMP-PNP has no effect on the Mt.MC1 complex. These results are consistent with a model for the ATPase cycle in which ATP hydrolysis occurs on the microtubule followed by detachment as the Ncd.ADP.Pi intermediate.
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Affiliation(s)
- K A Foster
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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45
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46
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Abstract
Kinesin is a microtubule-based motor protein that pulls vesicles or organelles towards the plus end of microtubules. Structural changes in the protein that drive motility are coupled to ATP binding and hydrolysis. Here, we attempt to integrate recent structural and kinetic results into a picture of the mechanochemical cycle of kinesin.
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Affiliation(s)
- E Mandelkow
- Max Planck Unit for Structural Molecular Biology, Hamburg, Germany.
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47
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Sablin EP, Case RB, Dai SC, Hart CL, Ruby A, Vale RD, Fletterick RJ. Direction determination in the minus-end-directed kinesin motor ncd. Nature 1998; 395:813-6. [PMID: 9796817 DOI: 10.1038/27463] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Motor proteins of the kinesin superfamily transport intracellular cargo along microtubules. Although different kinesin proteins share 30-50% amino-acid identity in their motor catalytic cores, some move to the plus end of microtubules whereas others travel in the opposite direction. Crystal structures of the catalytic cores of conventional kinesin (a plus-end-directed motor involved in organelle transport) and ncd (a minus-end-directed motor involved in chromosome segregation) are nearly identical; therefore, the structural basis for their opposite directions of movement is unknown. Here we show that the ncd 'neck' made up of 13 class-specific residues next to the superfamily-conserved catalytic core, is essential for minus-end-directed motility, as mutagenesis of these neck residues reverses the direction of ncd motion. By solving the 2.5 A structure of a functional ncd dimer, we show that the ncd neck (a coiled-coil) differs from the corresponding region in the kinesin neck (an interrupted beta-strand), although both necks interact with similar elements in the catalytic cores. The distinct neck architectures also confer different symmetries to the ncd and kinesin dimers and position these motors with appropriate directional bias on the microtubule.
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Affiliation(s)
- E P Sablin
- Department of Biochemistry/Biophysics, University of California, San Francisco 94143, USA
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48
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Grummt M, Woehlke G, Henningsen U, Fuchs S, Schleicher M, Schliwa M. Importance of a flexible hinge near the motor domain in kinesin-driven motility. EMBO J 1998; 17:5536-42. [PMID: 9755154 PMCID: PMC1170882 DOI: 10.1093/emboj/17.19.5536] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Conventional kinesin is a molecular motor consisting of an N-terminal catalytic motor domain, an extended stalk and a small globular C-terminus. Whereas the structure and function of the catalytic motor domain has been investigated, little is known about the function of domains outside the globular head. A short coiled-coil region adjacent to the motor domain, termed the neck, is known to be important for dimerization and may be required for kinesin processivity. We now provide evidence that a helix-disrupting hinge region (hinge 1) that separates the neck from the first extended coiled-coil of the stalk plays an essential role in basic motor activity. A fast fungal kinesin from Syncephalastrum racemosum was used for these studies. Deletion, substitution by a coiled-coil and truncation of the hinge 1 region all reduce motor speed and uncouple ATP turnover from gliding velocity. Insertion of hinge 1 regions from two conventional kinesins, Nkin and DmKHC, fully restores motor activity, whereas insertion of putative flexible linkers of other proteins does not, suggesting that hinge 1 regions of conventional kinesins can functionally replace each other. We suggest that this region is essential for kinesin movement in its promotion of chemo-mechanical coupling of the two heads and therefore the functional motor domain should be redefined to include not only the catalytic head but also the adjacent neck and hinge 1 domains.
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Affiliation(s)
- M Grummt
- Adolf-Butenandt-Institut, Zellbiologie, University of Munich, Schillerstrasse 42, 80336 Munich, Germany
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49
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Wriggers W, Schulten K. Nucleotide-dependent movements of the kinesin motor domain predicted by simulated annealing. Biophys J 1998; 75:646-61. [PMID: 9675167 PMCID: PMC1299740 DOI: 10.1016/s0006-3495(98)77555-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The structure of an ATP-bound kinesin motor domain is predicted and conformational differences relative to the known ADP-bound form of the protein are identified. The differences should be attributed to force-producing ATP hydrolysis. Candidate ATP-kinesin structures were obtained by simulated annealing, by placement of the ATP gamma-phosphate in the crystal structure of ADP-kinesin, and by interatomic distance constraints. The choice of such constraints was based on mutagenesis experiments, which identified Gly-234 as one of the gamma-phosphate sensing residues, as well as on structural comparison of kinesin with the homologous nonclaret disjunctional (ncd) motor and with G-proteins. The prediction of nucleotide-dependent conformational differences reveals an allosteric coupling between the nucleotide pocket and the microtubule binding site of kinesin. Interactions of ATP with Gly-234 and Ser-202 trigger structural changes in the motor domain, the nucleotide acting as an allosteric modifier of kinesin's microtubule-binding state. We suggest that in the presence of ATP kinesin's putative microtubule binding regions L8, L12, L11, alpha4, alpha5, and alpha6 form a face complementary in shape to the microtubule surface; in the presence of ADP, the microtubule binding face adopts a more convex shape relative to the ATP-bound form, reducing kinesin's affinity to the microtubule.
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Affiliation(s)
- W Wriggers
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
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50
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Hirose K, Cross RA, Amos LA. Nucleotide-dependent structural changes in dimeric NCD molecules complexed to microtubules. J Mol Biol 1998; 278:389-400. [PMID: 9571059 DOI: 10.1006/jmbi.1998.1709] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Complexes consisting of motor domains of the kinesin-like protein ncd bound to reassembled brain microtubules were visualised using cryoelectron microscopy and helical image reconstruction. Different nucleotide-associated states of a dimeric construct (NDelta295-700) of ncd were analysed to reveal ADP-containing, AMP.PNP-containing and empty (rigor) conformations. In these three states, each thought to mimic a different stage in ATP turnover, the double-headed motors attach to the microtubules by one head only, with the free head tethered in relatively fixed positions. The three structures differ both in the way the attached heads interact with tubulin and in the position of the tethered heads. In the strongly binding rigor and AMP.PNP (ATP-like) states, the attached head makes close contact with both subunits of a tubulin heterodimer. In the weakly bound ADP state, the contact made by the attached head with the monomer closer to the plus end appears to be more loose. Also, in the ATP-like state, the free head tilts nearer to the plus end than in the other two states. The data argue against model mechanisms in which a conformational change in the bound head guides the free head closer to its next binding site; on the contrary, the transition from ADP-filled via rigor to the AMP.PNP (ATP-like) state of the bound head produces a small motion of the free head in the counter-productive direction. However, the observation that the tethered head points towards the minus end, in all three states, is consistent with the idea that the relative arrangement of the heads in a dimer is a major determinant of directionality.
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Affiliation(s)
- K Hirose
- National Institute for Advanced Interdisciplinary Research, Tsukuba 305, Japan
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