1
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Neahring L, Cho NH, He Y, Liu G, Fernandes J, Rux CJ, Nakos K, Subramanian R, Upadhyayula S, Yildiz A, Dumont S. Torques within and outside the human spindle balance twist at anaphase. J Cell Biol 2024; 223:e202312046. [PMID: 38869473 PMCID: PMC11176257 DOI: 10.1083/jcb.202312046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 05/14/2024] [Accepted: 05/30/2024] [Indexed: 06/14/2024] Open
Abstract
At each cell division, nanometer-scale motors and microtubules give rise to the micron-scale spindle. Many mitotic motors step helically around microtubules in vitro, and most are predicted to twist the spindle in a left-handed direction. However, the human spindle exhibits only slight global twist, raising the question of how these molecular torques are balanced. Here, we find that anaphase spindles in the epithelial cell line MCF10A have a high baseline twist, and we identify factors that both increase and decrease this twist. The midzone motors KIF4A and MKLP1 are together required for left-handed twist at anaphase, and we show that KIF4A generates left-handed torque in vitro. The actin cytoskeleton also contributes to left-handed twist, but dynein and its cortical recruitment factor LGN counteract it. Together, our work demonstrates that force generators regulate twist in opposite directions from both within and outside the spindle, preventing strong spindle twist during chromosome segregation.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Nathan H. Cho
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Yifei He
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Gaoxiang Liu
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Jonathan Fernandes
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Caleb J. Rux
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
| | - Konstantinos Nakos
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Srigokul Upadhyayula
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Ahmet Yildiz
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Physics Department, University of California Berkeley, Berkeley, CA, USA
| | - Sophie Dumont
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental and Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
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2
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Bensel BM, Previs SB, Bookwalter C, Trybus KM, Walcott S, Warshaw DM. Kinesin-1-transported liposomes prefer to go straight in 3D microtubule intersections by a mechanism shared by other molecular motors. Proc Natl Acad Sci U S A 2024; 121:e2407330121. [PMID: 38980901 PMCID: PMC11260143 DOI: 10.1073/pnas.2407330121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Accepted: 05/24/2024] [Indexed: 07/11/2024] Open
Abstract
Kinesin-1 ensembles maneuver vesicular cargoes through the three-dimensional (3D) intracellular microtubule (MT) network. To define how such cargoes navigate MT intersections, we first determined how many kinesins from an ensemble on a lipid-based cargo simultaneously engage a MT, and then determined the directional outcomes (straight, turn, terminate) for liposome cargoes at perpendicular MT intersections. Run lengths of 350-nm diameter liposomes decorated with up to 20, constitutively active, truncated kinesin-1 KIF5B (K543) were longer than single motor transported cargo, suggesting multiple motor engagement. However, detachment forces of lipid-coated beads with ~20 kinesins, measured using an optical trap, showed no more than three simultaneously engaged motors, with a single engaged kinesin predominating, indicating anticooperative MT binding. At two-dimensional (2D) and 3D in vitro MT intersections, liposomes frequently paused (~2 s), suggesting kinesins simultaneously bind both MTs and engage in a tug-of-war. Liposomes showed no directional outcome bias in 2D (1.1 straight:turn ratio) but preferentially went straight (1.8 straight:turn ratio) in 3D intersections. To explain these data, we developed a mathematical model of liposome transport incorporating the known mechanochemistry of kinesins, which diffuse on the liposome surface, and have stiff tails in both compression and extension that impact how motors engage the intersecting MTs. Our model predicts the ~3 engaged motor limit observed in the optical trap and the bias toward going straight in 3D intersections. The striking similarity of these results to our previous study of liposome transport by myosin Va suggests a "universal" mechanism by which cargoes navigate 3D intersections.
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Affiliation(s)
- Brandon M. Bensel
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
| | - Samantha Beck Previs
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
| | - Carol Bookwalter
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
| | - Kathleen M. Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
| | - Sam Walcott
- Department of Mathematical Sciences, and Bioinformatics and Computational Biology, Worcester Polytechnic Institute, Worcester, MA01609
| | - David M. Warshaw
- Department of Molecular Physiology and Biophysics, University of Vermont Larner College of Medicine, Burlington, VT05405
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3
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Lo CH, Liu Z, Chen S, Lin F, Berneshawi AR, Yu CQ, Koo EB, Kowal TJ, Ning K, Hu Y, Wang WJ, Liao YJ, Sun Y. Primary cilia formation requires the Leigh syndrome-associated mitochondrial protein NDUFAF2. J Clin Invest 2024; 134:e175560. [PMID: 38949024 PMCID: PMC11213510 DOI: 10.1172/jci175560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 05/10/2024] [Indexed: 07/02/2024] Open
Abstract
Mitochondria-related neurodegenerative diseases have been implicated in the disruption of primary cilia function. Mutation in an intrinsic mitochondrial complex I component NDUFAF2 has been identified in Leigh syndrome, a severe inherited mitochondriopathy. Mutations in ARMC9, which encodes a basal body protein, cause Joubert syndrome, a ciliopathy with defects in the brain, kidney, and eye. Here, we report a mechanistic link between mitochondria metabolism and primary cilia signaling. We discovered that loss of NDUFAF2 caused both mitochondrial and ciliary defects in vitro and in vivo and identified NDUFAF2 as a binding partner for ARMC9. We also found that NDUFAF2 was both necessary and sufficient for cilia formation and that exogenous expression of NDUFAF2 rescued the ciliary and mitochondrial defects observed in cells from patients with known ARMC9 deficiency. NAD+ supplementation restored mitochondrial and ciliary dysfunction in ARMC9-deficient cells and zebrafish and ameliorated the ocular motility and motor deficits of a patient with ARMC9 deficiency. The present results provide a compelling mechanistic link, supported by evidence from human studies, between primary cilia and mitochondrial signaling. Importantly, our findings have significant implications for the development of therapeutic approaches targeting ciliopathies.
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Affiliation(s)
- Chien-Hui Lo
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Zhiquan Liu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Siyu Chen
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Frank Lin
- Department of Medicine, Stanford University, Palo Alto, California, USA
| | - Andrew R. Berneshawi
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Charles Q. Yu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Euna B. Koo
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Tia J. Kowal
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Ke Ning
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Yang Hu
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Won-Jing Wang
- Institute of Biochemistry and Molecular Biology, College of Life Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Y. Joyce Liao
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California, USA
- Palo Alto Veterans Administration, Palo Alto, California, USA
- Stanford Maternal and Child Health Research Institute and
- BioX, Stanford University School of Medicine, Palo Alto, California, USA
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4
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Meißner L, Niese L, Diez S. Helical motion and torque generation by microtubule motors. Curr Opin Cell Biol 2024; 88:102367. [PMID: 38735207 DOI: 10.1016/j.ceb.2024.102367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 05/14/2024]
Abstract
Microtubule motors play key roles in cellular functions, such as transport, mitosis and cell motility. Fueled by ATP hydrolysis, they convert chemical energy into mechanical work, which enables their movement on microtubules. While their motion along the long axis of microtubules has been studied extensively, some motors display an off-axis component, which results in helical motion around microtubules and the generation of torque in addition to linear forces. Understanding these nuanced movements expands our comprehension of motor protein dynamics and their impact on cellular processes.
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Affiliation(s)
- Laura Meißner
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307 Dresden, Germany
| | - Lukas Niese
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307 Dresden, Germany
| | - Stefan Diez
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307 Dresden, Germany; Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany; Cluster of Excellence Physics of Life, TUD Dresden University of Technology, 01062 Dresden, Germany.
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5
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Meißner L, Niese L, Schüring I, Mitra A, Diez S. Human kinesin-5 KIF11 drives the helical motion of anti-parallel and parallel microtubules around each other. EMBO J 2024; 43:1244-1256. [PMID: 38424239 PMCID: PMC10987665 DOI: 10.1038/s44318-024-00048-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
During mitosis, motor proteins and microtubule-associated protein organize the spindle apparatus by cross-linking and sliding microtubules. Kinesin-5 plays a vital role in spindle formation and maintenance, potentially inducing twist in the spindle fibers. The off-axis power stroke of kinesin-5 could generate this twist, but its implications in microtubule organization remain unclear. Here, we investigate 3D microtubule-microtubule sliding mediated by the human kinesin-5, KIF11, and found that the motor caused right-handed helical motion of anti-parallel microtubules around each other. The sidestepping ratio increased with reduced ATP concentration, indicating that forward and sideways stepping of the motor are not strictly coupled. Further, the microtubule-microtubule distance (motor extension) during sliding decreased with increasing sliding velocity. Intriguingly, parallel microtubules cross-linked by KIF11 orbited without forward motion, with nearly full motor extension. Altering the length of the neck linker increased the forward velocity and pitch of microtubules in anti-parallel overlaps. Taken together, we suggest that helical motion and orbiting of microtubules, driven by KIF11, contributes to flexible and context-dependent filament organization, as well as torque regulation within the mitotic spindle.
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Affiliation(s)
- Laura Meißner
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
- BASS Center, Molecular Biophysics and Biochemistry Department, Yale University, 06511, New Haven, USA
| | - Lukas Niese
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
| | - Irene Schüring
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
| | - Aniruddha Mitra
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, 3584CH, Utrecht, Netherlands
| | - Stefan Diez
- B CUBE - Center for Molecular Bioengineering, TUD Dresden University of Technology, 01307, Dresden, Germany.
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307, Dresden, Germany.
- Cluster of Excellence Physics of Life, TUD Dresden University of Technology, 01062, Dresden, Germany.
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6
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Sen A, Chowdhury D, Kunwar A. Coordination, cooperation, competition, crowding and congestion of molecular motors: Theoretical models and computer simulations. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2024; 141:563-650. [PMID: 38960486 DOI: 10.1016/bs.apcsb.2023.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
Cytoskeletal motor proteins are biological nanomachines that convert chemical energy into mechanical work to carry out various functions such as cell division, cell motility, cargo transport, muscle contraction, beating of cilia and flagella, and ciliogenesis. Most of these processes are driven by the collective operation of several motors in the crowded viscous intracellular environment. Imaging and manipulation of the motors with powerful experimental probes have been complemented by mathematical analysis and computer simulations of the corresponding theoretical models. In this article, we illustrate some of the key theoretical approaches used to understand how coordination, cooperation and competition of multiple motors in the crowded intra-cellular environment drive the processes that are essential for biological function of a cell. In spite of the focus on theory, experimentalists will also find this article as an useful summary of the progress made so far in understanding multiple motor systems.
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Affiliation(s)
- Aritra Sen
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Debashish Chowdhury
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India
| | - Ambarish Kunwar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India.
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7
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Neahring L, He Y, Cho NH, Liu G, Fernandes J, Rux CJ, Nakos K, Subramanian R, Upadhyayula S, Yildiz A, Dumont S. Torques within and outside the human spindle balance twist at anaphase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.10.570990. [PMID: 38405786 PMCID: PMC10888964 DOI: 10.1101/2023.12.10.570990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
At each cell division, nanometer-scale motors and microtubules give rise to the micron-scale spindle. Many mitotic motors step helically around microtubules in vitro, and most are predicted to twist the spindle in a left-handed direction. However, the human spindle exhibits only slight global twist, raising the question of how these molecular torques are balanced. Here, using lattice light sheet microscopy, we find that anaphase spindles in the epithelial cell line MCF10A have a high baseline twist, and we identify factors that both increase and decrease this twist. The midzone motors KIF4A and MKLP1 are redundantly required for left-handed twist at anaphase, and we show that KIF4A generates left-handed torque in vitro. The actin cytoskeleton also contributes to left-handed twist, but dynein and its cortical recruitment factor LGN counteract it. Together, our work demonstrates that force generators regulate twist in opposite directions from both within and outside the spindle, preventing strong spindle twist during chromosome segregation.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Yifei He
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Nathan H. Cho
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Gaoxiang Liu
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Jonathan Fernandes
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - Caleb J. Rux
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
| | - Konstantinos Nakos
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Srigokul Upadhyayula
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Ahmet Yildiz
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Physics Department, University of California Berkeley, Berkeley, CA, USA
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, University of California San Francisco, San Francisco, CA, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA, USA
- UC Berkeley/UC San Francisco Graduate Group in Bioengineering, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Department of Biochemistry & Biophysics, University of California San Francisco, San Francisco, CA, USA
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8
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Xie P. Determinant factors for residence time of kinesin motors at microtubule ends. J Biol Phys 2023; 49:77-93. [PMID: 36645568 PMCID: PMC9958224 DOI: 10.1007/s10867-022-09623-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/26/2022] [Indexed: 01/17/2023] Open
Abstract
Kinesins constitute a superfamily of microtubule (MT)-based motor proteins, which can perform diverse biological functions in cells such as transporting vesicle, regulating MT dynamics, and segregating chromosome. Some motors such as kinesin-1, kinesin-2, and kinesin-3 do the activity mainly on the MT lattice, while others such as kinesin-7 and kinesin-8 do the activity mainly at the MT plus end. To perform the different functions, it is required that the former motors can reside on the MT lattice for longer times than at the end, while the latter motors can reside at the MT plus end for long times. Here, a simple but general theory of the MT-end residence time of the kinesin motor is presented, with which the factors dictating the residence time are determined. The theory is further used to study specifically the MT-end residence times of Drosophila kinesin-1, kinesin-2/KIF3AB, kinesin-3/Unc104, kinesin-5/Eg5, kinesin-7/CENP-E, and kinesin-8/Kip3 motors, with the theoretical results being in agreement with the available experimental data.
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Affiliation(s)
- Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing, 100190, China.
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9
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Motor generated torque drives coupled yawing and orbital rotations of kinesin coated gold nanorods. Commun Biol 2022; 5:1368. [PMID: 36539506 PMCID: PMC9767927 DOI: 10.1038/s42003-022-04304-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Kinesin motor domains generate impulses of force and movement that have both translational and rotational (torque) components. Here, we ask how the torque component influences function in cargo-attached teams of weakly processive kinesins. Using an assay in which kinesin-coated gold nanorods (kinesin-GNRs) translocate on suspended microtubules, we show that for both single-headed KIF1A and dimeric ZEN-4, the intensities of polarized light scattered by the kinesin-GNRs in two orthogonal directions periodically oscillate as the GNRs crawl towards microtubule plus ends, indicating that translocating kinesin-GNRs unidirectionally rotate about their short (yaw) axes whilst following an overall left-handed helical orbit around the microtubule axis. For orientations of the GNR that generate a signal, the period of this short axis rotation corresponds to two periods of the overall helical trajectory. Torque force thus drives both rolling and yawing of near-spherical cargoes carrying rigidly-attached weakly processive kinesins, with possible relevance to intracellular transport.
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10
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Torque generating properties of Tetrahymena ciliary three-headed outer-arm dynein. Sci Rep 2022; 12:16722. [PMID: 36202966 PMCID: PMC9537190 DOI: 10.1038/s41598-022-21001-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 09/21/2022] [Indexed: 11/08/2022] Open
Abstract
Eukaryotic cilia/flagella are cellular bio-machines that drive the movement of microorganisms. Molecular motor axonemal dyneins in the axoneme, which consist of an 9 + 2 arrangement of microtubules, play an essential role in ciliary beating. Some axonemal dyneins have been shown to generate torque coupled with the longitudinal motility of microtubules across an array of dyneins fixed to the coverglass surface, resulting in a corkscrew-like translocation of microtubules. In this study, we performed three-dimensional tracking of a microbead coated with axonemal outer-arm dyneins on a freely suspended microtubule. We found that microbeads coated with multiple outer-arm dyneins exhibited continuous right-handed helical trajectories around the microtubule. This unidirectional helical motion differs from that of other types of cytoplasmic dyneins, which exhibit bidirectional helical motility. We also found that, in an in vitro microtubule gliding assay, gliding microtubules driven by outer-arm dyneins tend to turn to the left, causing a curved path, suggesting that the outer-arm dynein itself is able to rotate on its own axis. Two types of torque generated by the axonemal dyneins, corresponding to the forces used to rotate the microtubule unidirectionally with respect to the long and short axes, may regulate ciliary beating with complex waveforms.
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11
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Mechanisms of Regulation in Intraflagellar Transport. Cells 2022; 11:cells11172737. [PMID: 36078145 PMCID: PMC9454703 DOI: 10.3390/cells11172737] [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: 08/16/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Cilia are eukaryotic organelles essential for movement, signaling or sensing. Primary cilia act as antennae to sense a cell’s environment and are involved in a wide range of signaling pathways essential for development. Motile cilia drive cell locomotion or liquid flow around the cell. Proper functioning of both types of cilia requires a highly orchestrated bi-directional transport system, intraflagellar transport (IFT), which is driven by motor proteins, kinesin-2 and IFT dynein. In this review, we explore how IFT is regulated in cilia, focusing from three different perspectives on the issue. First, we reflect on how the motor track, the microtubule-based axoneme, affects IFT. Second, we focus on the motor proteins, considering the role motor action, cooperation and motor-train interaction plays in the regulation of IFT. Third, we discuss the role of kinases in the regulation of the motor proteins. Our goal is to provide mechanistic insights in IFT regulation in cilia and to suggest directions of future research.
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12
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The chirality of the mitotic spindle provides a mechanical response to forces and depends on microtubule motors and augmin. Curr Biol 2022; 32:2480-2493.e6. [PMID: 35537456 PMCID: PMC9235856 DOI: 10.1016/j.cub.2022.04.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/17/2022] [Accepted: 04/13/2022] [Indexed: 12/24/2022]
Abstract
Forces produced by motor proteins and microtubule dynamics within the mitotic spindle are crucial for proper chromosome segregation. In addition to linear forces, rotational forces or torques are present in the spindle, which are reflected in the left-handed twisted shapes of microtubule bundles that make the spindle chiral. However, the biological role and molecular origins of spindle chirality are unknown. By developing methods for measuring the spindle twist, we show that spindles are most chiral near the metaphase-to-anaphase transition. To assess the role of chirality in spindle mechanics, we compressed the spindles along their axis. This resulted in a stronger left-handed twist, suggesting that the twisted shape allows for a mechanical response to forces. Inhibition or depletion of motor proteins that perform chiral stepping, Eg5/kinesin-5, Kif18A/kinesin-8, MKLP1/kinesin-6, and dynein, decreased the left-handed twist or led to right-handed twist, implying that these motors regulate the twist by rotating microtubules within their antiparallel overlaps or at the spindle pole. A right-handed twist was also observed after the depletion of the microtubule nucleator augmin, indicating its contribution to the twist through the nucleation of antiparallel bridging microtubules. The uncovered switch from left-handed to right-handed twist reveals the existence of competing mechanisms that promote twisting in opposite directions. As round spindles are more twisted than the elongated ones are, we infer that bending and twisting moments are generated by similar molecular mechanisms and propose a physiological role for spindle chirality in allowing the spindle to absorb mechanical load. Video abstract
Spindle twist depends on torque-generating motors Eg5, Kif18A, MKLP1, and dynein Without the microtubule nucleator augmin, spindles show right-handed twist Compression of the spindle along the axis increases the left-handed twist Rounder spindles are more twisted than elongated ones are
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13
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Hu X, Dinu CZ. Microtubules and Quantum Dots Integration Leads to Conjugates with Applications in Biosensors and Bionanodevices. Methods Mol Biol 2022; 2430:133-148. [PMID: 35476330 DOI: 10.1007/978-1-0716-1983-4_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This chapter describes compiled methods for the formation and manipulation of microtubule-kinesin-carbon nanodots conjugates in user-defined synthetic environments. Specifically, by using inherited self-assembly and self-recognition properties of tubulin cytoskeletal protein and by interfacing this protein with lab synthesized carbon nanodots, bio-nano hybrid interfaces were formed. Further manipulation of such biohybrids under the mechanical cycle of kinesin 1 ATP-ase molecular motor led to their integration on user-controlled engineered surfaces. Presented methods are foreseen to lead to microtubule-molecular motor-hybrid based assemblies formation with applications ranging from biosensing, to nanoelectronics and single molecule printing, just to name a few.
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Affiliation(s)
- Xiao Hu
- Department of Chemical and Biomedical Engineering, West Virginia University, Benjamin M. Statler College of Engineering and Mineral Resources, Morgantown, WV, USA
- Department of Anatomy and Structural Biology and Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Cerasela Zoica Dinu
- Department of Chemical and Biomedical Engineering, West Virginia University, Benjamin M. Statler College of Engineering and Mineral Resources, Morgantown, WV, USA.
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14
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Neahring L, Cho NH, Dumont S. Opposing motors provide mechanical and functional robustness in the human spindle. Dev Cell 2021; 56:3006-3018.e5. [PMID: 34614397 DOI: 10.1016/j.devcel.2021.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/27/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
At each cell division, the spindle self-organizes from microtubules and motors. In human spindles, the motors dynein and Eg5 generate contractile and extensile stress, respectively. Inhibiting dynein or its targeting factor NuMA leads to unfocused, turbulent spindles, and inhibiting Eg5 leads to monopoles; yet, bipolar spindles form when both are inhibited together. What, then, are the roles of these opposing motors? Here, we generate NuMA/dynein- and Eg5-doubly inhibited spindles that not only attain a typical metaphase shape and size but also undergo anaphase. However, these spindles have reduced microtubule dynamics and are mechanically fragile, fracturing under force. Furthermore, they exhibit lagging chromosomes and a dramatic left-handed twist at anaphase. Thus, although these opposing motors are not required for spindle shape, they are essential to its mechanical and functional robustness. This work suggests a design principle whereby opposing active stresses provide robustness to force-generating cellular structures.
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Affiliation(s)
- Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA 94143, USA.
| | - Nathan H Cho
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA 94158, USA; Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA 94143, USA; Tetrad Graduate Program, UCSF, San Francisco, CA 94158, USA; Department of Biochemistry & Biophysics, UCSF, San Francisco, CA 94158, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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15
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Bujak Ł, Holanová K, García Marín A, Henrichs V, Barvík I, Braun M, Lánský Z, Piliarik M. Fast Leaps between Millisecond Confinements Govern Ase1 Diffusion along Microtubules. SMALL METHODS 2021; 5:e2100370. [PMID: 34927934 DOI: 10.1002/smtd.202100370] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/24/2021] [Indexed: 06/14/2023]
Abstract
Diffusion is the most fundamental mode of protein translocation within cells. Confined diffusion of proteins along the electrostatic potential constituted by the surface of microtubules, although modeled meticulously in molecular dynamics simulations, has not been experimentally observed in real-time. Here, interferometric scattering microscopy is used to directly visualize the movement of the microtubule-associated protein Ase1 along the microtubule surface at nanometer and microsecond resolution. Millisecond confinements of Ase1 and fast leaps between these positions of dwelling preferentially occurring along the microtubule protofilaments are resolved, revealing Ase1's mode of diffusive translocation along the microtubule's periodic surface. The derived interaction potential closely matches the tubulin-dimer periodicity and the distribution of the electrostatic potential on the microtubule lattice. It is anticipated that mapping the interaction landscapes for different proteins on microtubules, finding plausible energetic barriers of different positioning and heights, can provide valuable insights into regulating the dynamics of essential cytoskeletal processes, such as intracellular cargo trafficking, cell division, and morphogenesis, all of which rely on diffusive translocation of proteins along microtubules.
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Affiliation(s)
- Łukasz Bujak
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
| | - Kristýna Holanová
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
| | - Antonio García Marín
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
| | - Verena Henrichs
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 25250, Czech Republic
| | - Ivan Barvík
- Faculty of Mathematics and Physics, Institute of Physics, Charles University, Ke Karlovu 2026/5, Prague, 12116, Czech Republic
| | - Marcus Braun
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 25250, Czech Republic
| | - Zdeněk Lánský
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 25250, Czech Republic
| | - Marek Piliarik
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
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16
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Ciorîță A, Bugiel M, Sudhakar S, Schäffer E, Jannasch A. Single depolymerizing and transport kinesins stabilize microtubule ends. Cytoskeleton (Hoboken) 2021; 78:177-184. [PMID: 34310069 DOI: 10.1002/cm.21681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 11/07/2022]
Abstract
Microtubules are highly dynamic cellular filaments and an accurate control of their length is important for many intracellular processes like cell division. Among other factors, microtubule length is actively modulated by motors from the kinesin superfamily. For example, yeast kinesin-8, Kip3, motors depolymerize microtubules by a cooperative, force- and length-dependent mechanism. However, whether single motors can also depolymerize microtubules is unclear. Here, we measured how single kinesin motors influenced the stability of microtubules in an in vitro assay. Using label-free interference reflection microscopy, we determined the spontaneous microtubule depolymerization rate of stabilized microtubules in the presence of kinesins. Surprisingly, we found that both single Kip3 and nondepolymerizing kinesin-1 transport motors, used as a control, stabilized microtubules further. For Kip3, this behavior is contrary to the collective force-dependent depolymerization activity of multiple motors. Because of the control measurement, the finding may hint at a more general stabilization mechanism. The complex, concentration-dependent interaction with microtubule ends provides new insights into the molecular mechanism of kinesin-8 and its regulatory function of microtubule length.
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Affiliation(s)
- Alexandra Ciorîță
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.,National Institute for Research and Development of Isotopic and Molecular Technologies, Integrated Electron Microscopy Laboratory, Cluj-Napoca, Romania
| | - Michael Bugiel
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Swathi Sudhakar
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.,MRC London Institute of Medical Science, Imperial College London, London, UK
| | - Erik Schäffer
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Anita Jannasch
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
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17
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Xie P. A model of processive walking and slipping of kinesin-8 molecular motors. Sci Rep 2021; 11:8081. [PMID: 33850247 PMCID: PMC8044202 DOI: 10.1038/s41598-021-87532-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/31/2021] [Indexed: 12/20/2022] Open
Abstract
Kinesin-8 molecular motor can move with superprocessivity on microtubules towards the plus end by hydrolyzing ATP molecules, depolymerizing microtubules. The available single molecule data for yeast kinesin-8 (Kip3) motor showed that its superprocessive movement is frequently interrupted by brief stick-slip motion. Here, a model is presented for the chemomechanical coupling of the kinesin-8 motor. On the basis of the model, the dynamics of Kip3 motor is studied analytically. The analytical results reproduce quantitatively the available single molecule data on velocity without including the slip and that with including the slip versus external load at saturating ATP as well as slipping velocity versus external load at saturating ADP and no ATP. Predicted results on load dependence of stepping ratio at saturating ATP and load dependence of velocity at non-saturating ATP are provided. Similarities and differences between dynamics of kinesin-8 and that of kinesin-1 are discussed.
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Affiliation(s)
- Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
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18
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Yamagishi M, Maruyama Y, Sugawa M, Yajima J. Characterization of the motility of monomeric kinesin-5/Cin8. Biochem Biophys Res Commun 2021; 555:115-120. [PMID: 33845395 DOI: 10.1016/j.bbrc.2021.03.134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 03/24/2021] [Indexed: 12/30/2022]
Abstract
Cin8, the Saccharomyces cerevisiae kinesin-5, has an essential role in mitosis. In in vitro motility assays, tetrameric and dimeric Cin8 constructs showed bidirectional motility in response to ionic strength or Cin8 motor density. However, whether property-switching directionality is present in a monomeric form of Cin8 is unknown. Here we engineered monomeric Cin8 constructs with and without the Cin8-specific ∼99 residues in the loop 8 domain and examined the directionality of these constructs using an in vitro polarity-marked microtubule gliding assay within the range of the motor density or ionic strength. We found that both monomeric constructs showed only plus end-directed activity over the ranges measured, which suggested that minus end-directed motility driven by Cin8 is necessary for at least dimeric forms. Using an in vitro microtubule corkscrewing assay, we also found that monomeric Cin8 corkscrewed microtubules around their longitudinal axes with a constant left-handed pitch. Overall, our results imply that plus-end-directed and left-handed motor activity comprise the intrinsic properties of the Cin8 motor domain as with other monomeric N-kinesins.
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Affiliation(s)
- Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Yohei Maruyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Mitsuhiro Sugawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan; Komaba Institute for Science, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan; Komaba Institute for Science, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan; Research Center for Complex Systems Biology, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
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19
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Maruyama Y, Sugawa M, Yamaguchi S, Davies T, Osaki T, Kobayashi T, Yamagishi M, Takeuchi S, Mishima M, Yajima J. CYK4 relaxes the bias in the off-axis motion by MKLP1 kinesin-6. Commun Biol 2021; 4:180. [PMID: 33568771 PMCID: PMC7876049 DOI: 10.1038/s42003-021-01704-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 01/14/2021] [Indexed: 12/18/2022] Open
Abstract
Centralspindlin, a complex of the MKLP1 kinesin-6 and CYK4 GAP subunits, plays key roles in metazoan cytokinesis. CYK4-binding to the long neck region of MKLP1 restricts the configuration of the two MKLP1 motor domains in the centralspindlin. However, it is unclear how the CYK4-binding modulates the interaction of MKLP1 with a microtubule. Here, we performed three-dimensional nanometry of a microbead coated with multiple MKLP1 molecules on a freely suspended microtubule. We found that beads driven by dimeric MKLP1 exhibited persistently left-handed helical trajectories around the microtubule axis, indicating torque generation. By contrast, centralspindlin, like monomeric MKLP1, showed similarly left-handed but less persistent helical movement with occasional rightward movements. Analysis of the fluctuating helical movement indicated that the MKLP1 stochastically makes off-axis motions biased towards the protofilament on the left. CYK4-binding to the neck domains in MKLP1 enables more flexible off-axis motion of centralspindlin, which would help to avoid obstacles along crowded spindle microtubules. Analysing the 3D movement of MKLP1 motors, Maruyama et al. find that dimeric C. elegans MKLP1 drives a left-handed helical motion around the microtubule with minimum protofilament switching to the right side whereas less persistent motions are driven by monomers or by heterotetramers with CYK4. These findings suggest how obstacles along crowded spindle microtubules may be avoided by CYK4 binding to MKLP1.
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Affiliation(s)
- Yohei Maruyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Mitsuhiro Sugawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shin Yamaguchi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Tim Davies
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.,Department of Biosciences, Durham University, Durham, UK
| | - Toshihisa Osaki
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Takuya Kobayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shoji Takeuchi
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masanori Mishima
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan. .,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan. .,Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
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20
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Pavin N, Tolić IM. Mechanobiology of the Mitotic Spindle. Dev Cell 2020; 56:192-201. [PMID: 33238148 DOI: 10.1016/j.devcel.2020.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/06/2020] [Accepted: 11/02/2020] [Indexed: 10/22/2022]
Abstract
The mitotic spindle is a microtubule-based assembly that separates the chromosomes during cell division. As the spindle is basically a mechanical micro machine, the understanding of its functioning is constantly motivating the development of experimental approaches based on mechanical perturbations, which are complementary to and work together with the classical genetics and biochemistry methods. Recent data emerging from these approaches in combination with theoretical modeling led to novel ideas and significant revisions of the basic concepts in the field. In this Perspective, we discuss the advances in the understanding of spindle mechanics, focusing on microtubule forces that control chromosome movements.
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Affiliation(s)
- Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia.
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
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21
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Zhou Y, Zhao R, Schwarz EC, Akbar R, Kaba M, Pattu V, Helms V, Rieger H, Nunes-Hasler P, Qu B. Interorganelle Tethering to Endocytic Organelles Determines Directional Cytokine Transport in CD4 + T Cells. THE JOURNAL OF IMMUNOLOGY 2020; 205:2988-3000. [PMID: 33106338 DOI: 10.4049/jimmunol.2000195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 09/20/2020] [Indexed: 12/24/2022]
Abstract
Delivery of vesicles to their desired destinations plays a central role in maintaining proper cell functionality. In certain scenarios, depending on loaded cargos, the vesicles have spatially distinct destinations. For example, in T cells, some cytokines (e.g., IL-2) are polarized to the T cell-target cell interface, whereas the other cytokines are delivered multidirectionally (e.g., TNF-α). In this study, we show that in primary human CD4+ T cells, both TNF-α+ and IL-2+ vesicles can tether with endocytic organelles (lysosomes/late endosomes) by forming membrane contact sites. Tethered cytokine-containing vesicle (CytV)-endocytic organelle pairs are released sequentially. Only endocytic organelle-tethered CytVs are preferentially transported to their desired destination. Mathematical models suggest that endocytic organelle tethering could regulate the direction of cytokine transport by selectively attaching different microtubule motor proteins (such as kinesin and dynein) to the corresponding CytVs. These findings establish the previously unknown interorganelle tethering to endocytic organelles as a universal solution for directional cytokine transport in CD4+ T cells. Modulating tethering to endocytic organelles can, therefore, coordinately control directionally distinct cytokine transport.
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Affiliation(s)
- Yan Zhou
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Renping Zhao
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Eva C Schwarz
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Rahmad Akbar
- Center for Bioinformatics, Saarland University, 66123 Saarbrücken, Germany
| | - Mayis Kaba
- Department of Cell Physiology and Metabolism, University Medical Center, University of Geneva, 1211 Geneva, Switzerland
| | - Varsha Pattu
- Department of Physiology, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, 66123 Saarbrücken, Germany
| | - Heiko Rieger
- Department of Theoretical Physics, Saarland University, 66123 Saarbrücken, Germany
| | - Paula Nunes-Hasler
- Department of Cell Physiology and Metabolism, University Medical Center, University of Geneva, 1211 Geneva, Switzerland.,Department of Pathology and Immunology, University Medical Center, University of Geneva, 1211 Geneva, Switzerland; and
| | - Bin Qu
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine, School of Medicine, Saarland University, 66421 Homburg, Germany; .,Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
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22
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Yamagishi M, Fujimura S, Sugawa M, Nishizaka T, Yajima J. N‐terminal β‐strand of single‐headed kinesin‐1 can modulate the off‐axis force‐generation and resultant rotation pitch. Cytoskeleton (Hoboken) 2020; 77:351-361. [DOI: 10.1002/cm.21630] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/08/2020] [Accepted: 08/20/2020] [Indexed: 02/04/2023]
Affiliation(s)
- Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences The University of Tokyo Tokyo Japan
- Komaba Institute for Science The University of Tokyo Tokyo Japan
| | | | - Mitsuhiro Sugawa
- Department of Life Sciences, Graduate School of Arts and Sciences The University of Tokyo Tokyo Japan
- Komaba Institute for Science The University of Tokyo Tokyo Japan
| | | | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences The University of Tokyo Tokyo Japan
- Komaba Institute for Science The University of Tokyo Tokyo Japan
- Research Center for Complex Systems Biology The University of Tokyo Tokyo Japan
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23
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Abstract
Modern life is replete with function-expanding dongles, and life at the molecular scale is, it turns out, no exception. Hanging out of the back of the Kif14 molecular motor is an intrinsically disordered domain that gives it superpowers.
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Affiliation(s)
- Yean Ming Chew
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Coventry CV4 7LA, UK
| | - Robert A Cross
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Coventry CV4 7LA, UK.
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24
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Kinesin-14 motors drive a right-handed helical motion of antiparallel microtubules around each other. Nat Commun 2020; 11:2565. [PMID: 32444784 PMCID: PMC7244531 DOI: 10.1038/s41467-020-16328-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 04/08/2020] [Indexed: 12/30/2022] Open
Abstract
Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle. Some kinesins exhibit off-axis power strokes but their impact on motility and force generation in microtubule overlaps has not been investigated so far. Here authors use a 3D in vitro motility assay and find that Ndc’s off-axis motor forces generate torque in antiparallel microtubules which causes microtubule twisting and coiling.
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25
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Lin Y, Wei YL, She ZY. Kinesin-8 motors: regulation of microtubule dynamics and chromosome movements. Chromosoma 2020; 129:99-110. [PMID: 32417983 DOI: 10.1007/s00412-020-00736-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 02/01/2023]
Abstract
Microtubules are essential for intracellular transport, cell motility, spindle assembly, and chromosome segregation during cell division. Microtubule dynamics regulate the proper spindle organization and thus contribute to chromosome congression and segregation. Accumulating studies suggest that kinesin-8 motors are emerging regulators of microtubule dynamics and organizations. In this review, we provide an overview of the studies focused on kinesin-8 motors in cell division. We discuss the structures and molecular kinetics of kinesin-8 motors. We highlight the essential roles and mechanisms of kinesin-8 in the regulation of microtubule dynamics and spindle organization. We also shed light on the functions of kinesin-8 motors in chromosome movement and the spindle assembly checkpoint during the cell cycle.
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Affiliation(s)
- Yang Lin
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350011, Fujian, China.,Medical Research Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, Fujian, China
| | - Zhen-Yu She
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China. .,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China.
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26
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Bugiel M, Chugh M, Jachowski TJ, Schäffer E, Jannasch A. The Kinesin-8 Kip3 Depolymerizes Microtubules with a Collective Force-Dependent Mechanism. Biophys J 2020; 118:1958-1967. [PMID: 32229316 DOI: 10.1016/j.bpj.2020.02.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/29/2020] [Accepted: 02/25/2020] [Indexed: 12/28/2022] Open
Abstract
Microtubules are highly dynamic filaments with dramatic structural rearrangements and length changes during the cell cycle. An accurate control of the microtubule length is essential for many cellular processes, in particular during cell division. Motor proteins from the kinesin-8 family depolymerize microtubules by interacting with their ends in a collective and length-dependent manner. However, it is still unclear how kinesin-8 depolymerizes microtubules. Here, we tracked the microtubule end-binding activity of yeast kinesin-8, Kip3, under varying loads and nucleotide conditions using high-precision optical tweezers. We found that single Kip3 motors spent up to 200 s at the microtubule end and were not stationary there but took several 8-nm forward and backward steps that were suppressed by loads. Interestingly, increased loads, similar to increased motor concentrations, also exponentially decreased the motors' residence time at the microtubule end. On the microtubule lattice, loads also exponentially decreased the run length and time. However, for the same load, lattice run times were significantly longer compared to end residence times, suggesting the presence of a distinct force-dependent detachment mechanism at the microtubule end. The force dependence of the end residence time enabled us to estimate what force must act on a single motor to achieve the microtubule depolymerization speed of a motor ensemble. This force is higher than the stall force of a single Kip3 motor, supporting a collective force-dependent depolymerization mechanism that unifies the so-called "bump-off" and "switching" models. Understanding the mechanics of kinesin-8's microtubule end activity will provide important insights into cell division with implications for cancer research.
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Affiliation(s)
- Michael Bugiel
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Mayank Chugh
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Tobias Jörg Jachowski
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Erik Schäffer
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.
| | - Anita Jannasch
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.
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27
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Shi XX, Guo SK, Wang PY, Chen H, Xie P. All-atom molecular dynamics simulations reveal how kinesin transits from one-head-bound to two-heads-bound state. Proteins 2019; 88:545-557. [PMID: 31589786 DOI: 10.1002/prot.25833] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 08/19/2019] [Accepted: 09/17/2019] [Indexed: 12/15/2022]
Abstract
Kinesin dimer walks processively along a microtubule (MT) protofilament in a hand-over-hand manner, transiting alternately between one-head-bound (1HB) and two-heads-bound (2HB) states. In 1HB state, one head bound by adenosine diphosphate (ADP) is detached from MT and the other head is bound to MT. Here, using all-atom molecular dynamics simulations we determined the position and orientation of the detached ADP-head relative to the MT-bound head in 1HB state. We showed that in 1HB state when the MT-bound head is in ADP or nucleotide-free state, with its neck linker being undocked, the detached ADP-head and the MT-bound head have the high binding energy, and after adenosine triphosphate (ATP) binds to the MT-bound head, with its neck linker being docked, the binding energy between the two heads is reduced greatly. These results reveal how the kinesin dimer retains 1HB state before ATP binding and how the dimer transits from 1HB to 2HB state after ATP binding. Key residues involved in the head-head interaction in 1HB state were identified.
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Affiliation(s)
- Xiao-Xuan Shi
- School of Material Science and Engineering, Central South University of Forestry and Technology, Changsha, China.,Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Si-Kao Guo
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Peng-Ye Wang
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Hong Chen
- School of Materials Science and Energy Engineering, FoShan University, Guangdong, China
| | - Ping Xie
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
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28
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Kinetically distinct phases of tau on microtubules regulate kinesin motors and severing enzymes. Nat Cell Biol 2019; 21:1086-1092. [DOI: 10.1038/s41556-019-0374-6] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 07/18/2019] [Indexed: 11/09/2022]
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29
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Mickolajczyk KJ, Cook ASI, Jevtha JP, Fricks J, Hancock WO. Insights into Kinesin-1 Stepping from Simulations and Tracking of Gold Nanoparticle-Labeled Motors. Biophys J 2019; 117:331-345. [PMID: 31301807 DOI: 10.1016/j.bpj.2019.06.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 02/02/2023] Open
Abstract
High-resolution tracking of gold nanoparticle-labeled proteins has emerged as a powerful technique for measuring the structural kinetics of processive enzymes and other biomacromolecules. These techniques use point spread function (PSF) fitting methods borrowed from single-molecule fluorescence imaging to determine molecular positions below the diffraction limit. However, compared to fluorescence, gold nanoparticle tracking experiments are performed at significantly higher frame rates and utilize much larger probes. In the current work, we use Brownian dynamics simulations of nanoparticle-labeled proteins to investigate the regimes in which the fundamental assumptions of PSF fitting hold and where they begin to break down. We find that because gold nanoparticles undergo tethered diffusion around their anchor point, PSF fitting cannot be extended to arbitrarily fast frame rates. Instead, camera exposure times that allow the nanoparticle to fully populate its stationary positional distribution achieve a spatial averaging that increases fitting precision. We furthermore find that changes in the rotational freedom of the tagged protein can lead to artifactual translations in the fitted particle position. Finally, we apply these lessons to dissect a standing controversy in the kinesin field over the structure of a dimer in the ATP waiting state. Combining new experiments with simulations, we determine that the rear kinesin head in the ATP waiting state is unbound but not displaced from its previous microtubule binding site and that apparent differences in separately published reports were simply due to differences in the gold nanoparticle attachment position. Our results highlight the importance of gold conjugation decisions and imaging parameters to high-resolution tracking results and will serve as a useful guide for the design of future gold nanoparticle tracking experiments.
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Affiliation(s)
- Keith J Mickolajczyk
- Department of Biomedical Engineering; Intercollege Graduate Degree Program in Bioengineering
| | - Annan S I Cook
- Department of Biomedical Engineering; Department of Physics, Pennsylvania State University, University Park, Pennsylvania
| | | | - John Fricks
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, Arizona
| | - William O Hancock
- Department of Biomedical Engineering; Intercollege Graduate Degree Program in Bioengineering.
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30
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Mitra A, Suñé M, Diez S, Sancho JM, Oriola D, Casademunt J. A Brownian Ratchet Model Explains the Biased Sidestepping of Single-Headed Kinesin-3 KIF1A. Biophys J 2019; 116:2266-2274. [PMID: 31155147 PMCID: PMC6588830 DOI: 10.1016/j.bpj.2019.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/21/2019] [Accepted: 05/13/2019] [Indexed: 12/12/2022] Open
Abstract
The kinesin-3 motor KIF1A is involved in long-ranged axonal transport in neurons. To ensure vesicular delivery, motors need to navigate the microtubule lattice and overcome possible roadblocks along the way. The single-headed form of KIF1A is a highly diffusive motor that has been shown to be a prototype of a Brownian motor by virtue of a weakly bound diffusive state to the microtubule. Recently, groups of single-headed KIF1A motors were found to be able to sidestep along the microtubule lattice, creating left-handed helical membrane tubes when pulling on giant unilamellar vesicles in vitro. A possible hypothesis is that the diffusive state enables the motor to explore the microtubule lattice and switch protofilaments, leading to a left-handed helical motion. Here, we study the longitudinal rotation of microtubules driven by single-headed KIF1A motors using fluorescence-interference contrast microscopy. We find an average rotational pitch of ≃1.5μm, which is remarkably robust to changes in the gliding velocity, ATP concentration, microtubule length, and motor density. Our experimental results are compared to stochastic simulations of Brownian motors moving on a two-dimensional continuum ratchet potential, which quantitatively agree with the fluorescence-interference contrast experiments. We find that single-headed KIF1A sidestepping can be explained as a consequence of the intrinsic handedness and polarity of the microtubule lattice in combination with the diffusive mechanochemical cycle of the motor.
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Affiliation(s)
- Aniruddha Mitra
- Center for Molecular and Cellular Bioengineering, B CUBE, Technische Universität Dresden, Dresden, Germany
| | - Marc Suñé
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - Stefan Diez
- Center for Molecular and Cellular Bioengineering, B CUBE, Technische Universität Dresden, Dresden, Germany; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - José M Sancho
- Departament de Física de la Matèria Condensada, Facultat de Física, University of Barcelona, Barcelona, Spain; University of Barcelona Institute of Complex Systems, University of Barcelona, Barcelona, Spain
| | - David Oriola
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany.
| | - Jaume Casademunt
- Departament de Física de la Matèria Condensada, Facultat de Física, University of Barcelona, Barcelona, Spain; University of Barcelona Institute of Complex Systems, University of Barcelona, Barcelona, Spain
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31
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Gicking AM, Wang P, Liu C, Mickolajczyk KJ, Guo L, Hancock WO, Qiu W. The Orphan Kinesin PAKRP2 Achieves Processive Motility via a Noncanonical Stepping Mechanism. Biophys J 2019; 116:1270-1281. [PMID: 30902363 DOI: 10.1016/j.bpj.2019.02.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 02/07/2019] [Accepted: 02/19/2019] [Indexed: 12/27/2022] Open
Abstract
Phragmoplast-associated kinesin-related protein 2 (PAKRP2) is an orphan kinesin in Arabidopsis thaliana that is thought to transport vesicles along phragmoplast microtubules for cell plate formation. Here, using single-molecule fluorescence microscopy, we show that PAKRP2 is the first orphan kinesin to exhibit processive plus-end-directed motility on single microtubules as individual homodimers. Our results show that PAKRP2 processivity is achieved despite having an exceptionally long (32 residues) neck linker. Furthermore, using high-resolution nanoparticle tracking, we find that PAKRP2 steps via a hand-over-hand mechanism that includes frequent side steps, a prolonged diffusional search of the tethered head, and tight coupling of the ATP hydrolysis cycle to the forward-stepping cycle. Interestingly, truncating the PAKRP2 neck linker to 14 residues decreases the run length of PAKRP2; thus, the long neck linker enhances the processive behavior. Based on the canonical model of kinesin stepping, such a long neck linker is expected to decrease the processivity and disrupt the coupling of ATP hydrolysis to forward stepping. Therefore, we conclude that PAKRP2 employs a noncanonical strategy for processive motility, wherein a long neck linker is coupled with a slow ATP hydrolysis rate to allow for an extended diffusional search during each step without sacrificing processivity or efficiency.
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Affiliation(s)
| | - Pan Wang
- Department of Physics, Oregon State University, Corvallis, Oregon; School of Physics and Electronics, Henan University, Kaifeng, Henan, China
| | - Chun Liu
- Pearl River Fisheries Research Institute, Guangzhou, China
| | - Keith J Mickolajczyk
- Department of Biomedical Engineering, Penn State University, University Park, Pennsylvania; Intercollege Graduate Degree Program in Bioengineering, Penn State University, University Park, Pennsylvania
| | - Lijun Guo
- School of Physics and Electronics, Henan University, Kaifeng, Henan, China
| | - William O Hancock
- Department of Biomedical Engineering, Penn State University, University Park, Pennsylvania; Intercollege Graduate Degree Program in Bioengineering, Penn State University, University Park, Pennsylvania
| | - Weihong Qiu
- Department of Physics, Oregon State University, Corvallis, Oregon; Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon.
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32
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Bugiel M, Schäffer E. Three-Dimensional Optical Tweezers Tracking Resolves Random Sideward Steps of the Kinesin-8 Kip3. Biophys J 2018; 115:1993-2002. [PMID: 30360926 DOI: 10.1016/j.bpj.2018.09.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/30/2018] [Accepted: 09/24/2018] [Indexed: 01/10/2023] Open
Abstract
The budding yeast kinesin-8 Kip3 is a highly processive motor protein that walks to the ends of cytoskeletal microtubules and shortens them in a collective manner. However, how exactly Kip3 reaches the microtubule end is unclear. Although rotations of microtubules in multimotored Kip3 gliding assays implied directed sideward switching between microtubule protofilaments, two-dimensional, single-molecule, optical-tweezers assays indicated that Kip3 randomly switched protofilaments. Here, we topographically suspended microtubules such that Kip3 motors could freely access the microtubules in three dimensions. Tracking single-motor-driven microspheres with a three-dimensional, zero-load, optical-tweezers-based force clamp showed that Kip3 switched protofilaments in discrete steps equally frequent in both directions. A statistical analysis confirmed the diffusive sideward motion of Kip3, consistent with the two-dimensional single-molecule results. Furthermore, we found that motors were in one of three states: either not switching protofilaments or switching between them with a slow or fast sideward-stepping rate. Interestingly, this sideward diffusion was limited to one turn, suggesting that motors could not cross the microtubule seam. The diffusive protofilament switching may enable Kip3 to efficiently bypass obstacles and reach the microtubule end for length regulation.
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Affiliation(s)
- Michael Bugiel
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Erik Schäffer
- Cellular Nanoscience, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.
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