1
|
Fineberg A, Takagi Y, Thirumurugan K, Andrecka J, Billington N, Young G, Cole D, Burgess SA, Curd AP, Hammer JA, Sellers JR, Kukura P, Knight PJ. Myosin-5 varies its step length to carry cargo straight along the irregular F-actin track. Proc Natl Acad Sci U S A 2024; 121:e2401625121. [PMID: 38507449 PMCID: PMC10990141 DOI: 10.1073/pnas.2401625121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 02/15/2024] [Indexed: 03/22/2024] Open
Abstract
Molecular motors employ chemical energy to generate unidirectional mechanical output against a track while navigating a chaotic cellular environment, potential disorder on the track, and against Brownian motion. Nevertheless, decades of nanometer-precise optical studies suggest that myosin-5a, one of the prototypical molecular motors, takes uniform steps spanning 13 subunits (36 nm) along its F-actin track. Here, we use high-resolution interferometric scattering microscopy to reveal that myosin takes strides spanning 22 to 34 actin subunits, despite walking straight along the helical actin filament. We show that cumulative angular disorder in F-actin accounts for the observed proportion of each stride length, akin to crossing a river on variably spaced stepping stones. Electron microscopy revealed the structure of the stepping molecule. Our results indicate that both motor and track are soft materials that can adapt to function in complex cellular conditions.
Collapse
Affiliation(s)
- Adam Fineberg
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, OxfordOX1 3QZ, United Kingdom
- Laboratory of Single Molecule Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD20892
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD20892
| | - Kavitha Thirumurugan
- Astbury Centre for Structural Molecular Biology, and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Joanna Andrecka
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, OxfordOX1 3QZ, United Kingdom
| | - Neil Billington
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD20892
| | - Gavin Young
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, OxfordOX1 3QZ, United Kingdom
| | - Daniel Cole
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, OxfordOX1 3QZ, United Kingdom
| | - Stan A. Burgess
- Astbury Centre for Structural Molecular Biology, and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - Alistair P. Curd
- Astbury Centre for Structural Molecular Biology, and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LeedsLS2 9JT, United Kingdom
| | - John A. Hammer
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD20892
| | - James R. Sellers
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD20892
| | - Philipp Kukura
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, OxfordOX1 3QZ, United Kingdom
- The Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, University of Oxford, OxfordOX1 3QU, United Kingdom
| | - Peter J. Knight
- Astbury Centre for Structural Molecular Biology, and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LeedsLS2 9JT, United Kingdom
| |
Collapse
|
2
|
Fineberg A, Takagi Y, Thirumurugan K, Andrecka J, Billington N, Young G, Cole D, Burgess SA, Curd AP, Hammer JA, Sellers JR, Kukura P, Knight PJ. Myosin-5 varies its steps along the irregular F-actin track. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.16.549178. [PMID: 37503193 PMCID: PMC10370000 DOI: 10.1101/2023.07.16.549178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Molecular motors employ chemical energy to generate unidirectional mechanical output against a track. By contrast to the majority of macroscopic machines, they need to navigate a chaotic cellular environment, potential disorder in the track and Brownian motion. Nevertheless, decades of nanometer-precise optical studies suggest that myosin-5a, one of the prototypical molecular motors, takes uniform steps spanning 13 subunits (36 nm) along its F-actin track. Here, we use high-resolution interferometric scattering (iSCAT) microscopy to reveal that myosin takes strides spanning 22 to 34 actin subunits, despite walking straight along the helical actin filament. We show that cumulative angular disorder in F-actin accounts for the observed proportion of each stride length, akin to crossing a river on variably-spaced stepping stones. Electron microscopy revealed the structure of the stepping molecule. Our results indicate that both motor and track are soft materials that can adapt to function in complex cellular conditions.
Collapse
Affiliation(s)
- Adam Fineberg
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
- Laboratory of Single Molecule Biophysics, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, U.S.A
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, U.S.A
| | - Kavitha Thirumurugan
- Astbury Centre for Structural Molecular Biology, and Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, U.K
- Present address: Structural Biology Lab, Pearl Research Park, SBST, Vellore Institute of Technology, Vellore-632 014, India
| | - Joanna Andrecka
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
- Present address: Human Technopole, Viale Rita Levi-Montalcini 1, 20157, Milan, Italy
| | - Neil Billington
- Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, U.S.A
- Present address: Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, U.S.A
| | - Gavin Young
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
- Present address: Refeyn Ltd., Unit 9, Trade City, Sandy Ln W, Littlemore, Oxford OX4 6FF, U.K
| | - Daniel Cole
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
- Present address: Refeyn Ltd., Unit 9, Trade City, Sandy Ln W, Littlemore, Oxford OX4 6FF, U.K
| | - Stan A. Burgess
- Astbury Centre for Structural Molecular Biology, and Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, U.K
| | - Alistair P. Curd
- Astbury Centre for Structural Molecular Biology, and Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, U.K
| | - John A. Hammer
- Cell and Developmental Biology Center, NHLBI, National Institutes of Health, Bethesda, MD 20892, U.S.A
| | - James R. Sellers
- Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, U.S.A
| | - Philipp Kukura
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, U.K
- The Kavli Institute for Nanoscience Discovery, Dorothy Crowfoot Hodgkin Building, University of Oxford, South Parks Rd, Oxford OX1 3QU, U.K
| | - Peter J. Knight
- Astbury Centre for Structural Molecular Biology, and Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, U.K
| |
Collapse
|
3
|
Sellers JR, Takagi Y. How Myosin 5 Walks Deduced from Single-Molecule Biophysical Approaches. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1239:153-181. [PMID: 32451859 DOI: 10.1007/978-3-030-38062-5_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Myosin 5a is a two-headed myosin that functions as a cargo transporter in cells. To accomplish this task it has evolved several unique structural and kinetic features that allow it to move processively as a single molecule along actin filaments. A plethora of biophysical techniques have been used to elucidate the detailed mechanism of its movement along actin filaments in vitro. This chapter describes how this mechanism was deduced.
Collapse
Affiliation(s)
- James R Sellers
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
4
|
Myosin Va transport of liposomes in three-dimensional actin networks is modulated by actin filament density, position, and polarity. Proc Natl Acad Sci U S A 2019; 116:8326-8335. [PMID: 30967504 DOI: 10.1073/pnas.1901176116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cell's dense 3D actin filament network presents numerous challenges to vesicular transport by teams of myosin Va (MyoVa) molecular motors. These teams must navigate their cargo through diverse actin structures ranging from Arp2/3-branched lamellipodial networks to the dense, unbranched cortical networks. To define how actin filament network organization affects MyoVa cargo transport, we created two different 3D actin networks in vitro. One network was comprised of randomly oriented, unbranched actin filaments; the other was comprised of Arp2/3-branched actin filaments, which effectively polarized the network by aligning the actin filament plus-ends. Within both networks, we defined each actin filament's 3D spatial position using superresolution stochastic optical reconstruction microscopy (STORM) and its polarity by observing the movement of single fluorescent reporter MyoVa. We then characterized the 3D trajectories of fluorescent, 350-nm fluid-like liposomes transported by MyoVa teams (∼10 motors) moving within each of the two networks. Compared with the unbranched network, we observed more liposomes with directed and fewer with stationary motion on the Arp2/3-branched network. This suggests that the modes of liposome transport by MyoVa motors are influenced by changes in the local actin filament polarity alignment within the network. This mechanism was supported by an in silico 3D model that provides a broader platform to understand how cellular regulation of the actin cytoskeletal architecture may fine tune MyoVa-based intracellular cargo transport.
Collapse
|
5
|
Brown AI, Sivak DA. Allocating and Splitting Free Energy to Maximize Molecular Machine Flux. J Phys Chem B 2018; 122:1387-1393. [PMID: 29290114 DOI: 10.1021/acs.jpcb.7b10621] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Biomolecular machines transduce between different forms of energy. These machines make directed progress and increase their speed by consuming free energy, typically in the form of nonequilibrium chemical concentrations. Machine dynamics are often modeled by transitions between a set of discrete metastable conformational states. In general, the free-energy change associated with each transition can increase the forward rate constant, decrease the reverse rate constant, or both. In contrast to previous optimizations, we find that in general flux is maximized neither by devoting all free-energy changes to increasing forward rate constants nor by solely decreasing reverse rate constants. Instead, the optimal free-energy splitting depends on the detailed dynamics. Extending our analysis to machines with vulnerable states (from which they can break down), in the strong driving corresponding to in vivo cellular conditions, processivity is maximized by reducing the occupation of the vulnerable state.
Collapse
Affiliation(s)
- Aidan I Brown
- Department of Physics, Simon Fraser University , Burnaby, British Columbia V5A1S6, Canada
| | - David A Sivak
- Department of Physics, Simon Fraser University , Burnaby, British Columbia V5A1S6, Canada
| |
Collapse
|
6
|
Lombardo AT, Nelson SR, Ali MY, Kennedy GG, Trybus KM, Walcott S, Warshaw DM. Myosin Va molecular motors manoeuvre liposome cargo through suspended actin filament intersections in vitro. Nat Commun 2017; 8:15692. [PMID: 28569841 PMCID: PMC5461480 DOI: 10.1038/ncomms15692] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 04/13/2017] [Indexed: 01/15/2023] Open
Abstract
Intracellular cargo transport relies on myosin Va molecular motor ensembles to travel along the cell's three-dimensional (3D) highway of actin filaments. At actin filament intersections, the intersecting filament is a structural barrier to and an alternate track for directed cargo transport. Here we use 3D super-resolution fluorescence imaging to determine the directional outcome (that is, continues straight, turns or terminates) for an ∼10 motor ensemble transporting a 350 nm lipid-bound cargo that encounters a suspended 3D actin filament intersection in vitro. Motor–cargo complexes that interact with the intersecting filament go straight through the intersection 62% of the time, nearly twice that for turning. To explain this, we develop an in silico model, supported by optical trapping data, suggesting that the motors' diffusive movements on the vesicle surface and the extent of their engagement with the two intersecting actin tracks biases the motor–cargo complex on average to go straight through the intersection. Cellular cargo transported along actin filaments is faced with a directional choice at an intersection. Here the authors show that myosin Va-bound cargo prefers to go straight through the intersection, and propose a model to explain this by a tug-of-war between motors on the lipid cargo that engage the actin tracks.
Collapse
Affiliation(s)
- Andrew T Lombardo
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | - Shane R Nelson
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | - M Yusuf Ali
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | - Guy G Kennedy
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | - Kathleen M Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | - Sam Walcott
- Department of Mathematics, University of California, Davis, California 95616, USA
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| |
Collapse
|
7
|
Sato O, Komatsu S, Sakai T, Tsukasaki Y, Tanaka R, Mizutani T, Watanabe TM, Ikebe R, Ikebe M. Human myosin VIIa is a very slow processive motor protein on various cellular actin structures. J Biol Chem 2017; 292:10950-10960. [PMID: 28507101 DOI: 10.1074/jbc.m116.765966] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 05/11/2017] [Indexed: 11/06/2022] Open
Abstract
Human myosin VIIa (MYO7A) is an actin-linked motor protein associated with human Usher syndrome (USH) type 1B, which causes human congenital hearing and visual loss. Although it has been thought that the role of human myosin VIIa is critical for USH1 protein tethering with actin and transportation along actin bundles in inner-ear hair cells, myosin VIIa's motor function remains unclear. Here, we studied the motor function of the tail-truncated human myosin VIIa dimer (HM7AΔTail/LZ) at the single-molecule level. We found that the HM7AΔTail/LZ moves processively on single actin filaments with a step size of 35 nm. Dwell-time distribution analysis indicated an average waiting time of 3.4 s, yielding ∼0.3 s-1 for the mechanical turnover rate; hence, the velocity of HM7AΔTail/LZ was extremely slow, at 11 nm·s-1 We also examined HM7AΔTail/LZ movement on various actin structures in demembranated cells. HM7AΔTail/LZ showed unidirectional movement on actin structures at cell edges, such as lamellipodia and filopodia. However, HM7AΔTail/LZ frequently missed steps on actin tracks and exhibited bidirectional movement at stress fibers, which was not observed with tail-truncated myosin Va. These results suggest that the movement of the human myosin VIIa motor protein is more efficient on lamellipodial and filopodial actin tracks than on stress fibers, which are composed of actin filaments with different polarity, and that the actin structures influence the characteristics of cargo transportation by human myosin VIIa. In conclusion, myosin VIIa movement appears to be suitable for translocating USH1 proteins on stereocilia actin bundles in inner-ear hair cells.
Collapse
Affiliation(s)
- Osamu Sato
- From the Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708
| | - Satoshi Komatsu
- From the Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708
| | - Tsuyoshi Sakai
- From the Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708
| | - Yoshikazu Tsukasaki
- From the Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708.,Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612
| | - Ryosuke Tanaka
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814, Japan
| | - Takeomi Mizutani
- Department of Advanced Transdisciplinary Sciences, Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan, and
| | - Tomonobu M Watanabe
- Laboratory for Comprehensive Bioimaging, RIKEN Quantitative Biology Center, Suita, Osaka 565-0874, Japan
| | - Reiko Ikebe
- From the Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708
| | - Mitsuo Ikebe
- From the Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas 75708,
| |
Collapse
|
8
|
Egan P, Moore J, Schunn C, Cagan J, LeDuc P. Emergent systems energy laws for predicting myosin ensemble processivity. PLoS Comput Biol 2015; 11:e1004177. [PMID: 25885169 PMCID: PMC4401713 DOI: 10.1371/journal.pcbi.1004177] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/05/2015] [Indexed: 11/18/2022] Open
Abstract
In complex systems with stochastic components, systems laws often emerge that describe higher level behavior regardless of lower level component configurations. In this paper, emergent laws for describing mechanochemical systems are investigated for processive myosin-actin motility systems. On the basis of prior experimental evidence that longer processive lifetimes are enabled by larger myosin ensembles, it is hypothesized that emergent scaling laws could coincide with myosin-actin contact probability or system energy consumption. Because processivity is difficult to predict analytically and measure experimentally, agent-based computational techniques are developed to simulate processive myosin ensembles and produce novel processive lifetime measurements. It is demonstrated that only systems energy relationships hold regardless of isoform configurations or ensemble size, and a unified expression for predicting processive lifetime is revealed. The finding of such laws provides insight for how patterns emerge in stochastic mechanochemical systems, while also informing understanding and engineering of complex biological systems.
Collapse
Affiliation(s)
- Paul Egan
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Jeffrey Moore
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Christian Schunn
- Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jonathan Cagan
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Philip LeDuc
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| |
Collapse
|
9
|
Boon NJ, Hoyle RB. Detachment, futile cycling, and nucleotide pocket collapse in myosin-V stepping. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:022717. [PMID: 25768541 DOI: 10.1103/physreve.91.022717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Indexed: 06/04/2023]
Abstract
Myosin-V is a highly processive dimeric protein that walks with 36-nm steps along actin tracks, powered by coordinated adenosine triphosphate (ATP) hydrolysis reactions in the two myosin heads. No previous theoretical models of the myosin-V walk reproduce all the observed trends of velocity and run length with adenosine diphosphate (ADP), ATP and external forcing. In particular, a result that has eluded all theoretical studies based upon rigorous physical chemistry is that run length decreases with both increasing [ADP] and [ATP]. We systematically analyze which mechanisms in existing models reproduce which experimental trends and use this information to guide the development of models that can reproduce them all. We formulate models as reaction networks between distinct mechanochemical states with energetically determined transition rates. For each network architecture, we compare predictions for velocity and run length to a subset of experimentally measured values, and fit unknown parameters using a bespoke Monte Carlo simulated annealing optimization routine. Finally we determine which experimental trends are replicated by the best-fit model for each architecture. Only two models capture them all: one involving [ADP]-dependent mechanical detachment, and another including [ADP]-dependent futile cycling and nucleotide pocket collapse. Comparing model-predicted and experimentally observed kinetic transition rates favors the latter.
Collapse
Affiliation(s)
- Neville J Boon
- Department of Mathematics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Rebecca B Hoyle
- Department of Mathematics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
- Mathematical Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| |
Collapse
|
10
|
Diensthuber RP, Tominaga M, Preller M, Hartmann FK, Orii H, Chizhov I, Oiwa K, Tsiavaliaris G. Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor. FASEB J 2015; 29:81-94. [PMID: 25326536 DOI: 10.1096/fj.14-254763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The 175-kDa myosin-11 from Nicotiana tabacum (Nt(175kDa)myosin-11) is exceptional in its mechanical activity as it is the fastest known processive actin-based motor, moving 10 times faster than the structurally related class 5 myosins. Although this ability might be essential for long-range organelle transport within larger plant cells, the kinetic features underlying the fast processive movement of Nt(175kDa)myosin-11 still remain unexplored. To address this, we generated a single-headed motor domain construct and carried out a detailed kinetic analysis. The data demonstrate that Nt(175kDa)myosin-11 is a high duty ratio motor, which remains associated with actin most of its enzymatic cycle. However, different from other processive myosins that establish a high duty ratio on the basis of a rate-limiting ADP-release step, Nt(175kDa)myosin-11 achieves a high duty ratio by a prolonged duration of the ATP-induced isomerization of the actin-bound states and ADP release kinetics, both of which in terms of the corresponding time constants approach the total ATPase cycle time. Molecular modeling predicts that variations in the charge distribution of the actin binding interface might contribute to the thermodynamic fine-tuning of the kinetics of this myosin. Our study unravels a new type of a high duty ratio motor and provides important insights into the molecular mechanism of processive movement of higher plant myosins.
Collapse
Affiliation(s)
- Ralph P Diensthuber
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Motoki Tominaga
- Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan; Science and Technology Agency, PRESTO, Saitama, Japan
| | - Matthias Preller
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany; Centre for Structural Systems Biology, German Electron Synchrotron (DESY), Hamburg, Germany
| | - Falk K Hartmann
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Hidefumi Orii
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and
| | - Igor Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Kazuhiro Oiwa
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe, Japan
| | | |
Collapse
|
11
|
Motor coupling through lipid membranes enhances transport velocities for ensembles of myosin Va. Proc Natl Acad Sci U S A 2014; 111:E3986-95. [PMID: 25201964 DOI: 10.1073/pnas.1406535111] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Myosin Va is an actin-based molecular motor responsible for transport and positioning of a wide array of intracellular cargoes. Although myosin Va motors have been well characterized at the single-molecule level, physiological transport is carried out by ensembles of motors. Studies that explore the behavior of ensembles of molecular motors have used nonphysiological cargoes such as DNA linkers or glass beads, which do not reproduce one key aspect of vesicular systems--the fluid intermotor coupling of biological lipid membranes. Using a system of defined synthetic lipid vesicles (100- to 650-nm diameter) composed of either 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) (fluid at room temperature) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (gel at room temperature) with a range of surface densities of myosin Va motors (32-125 motors per μm(2)), we demonstrate that the velocity of vesicle transport by ensembles of myosin Va is sensitive to properties of the cargo. Gel-state DPPC vesicles bound with multiple motors travel at velocities equal to or less than vesicles with a single myosin Va (∼450 nm/s), whereas surprisingly, ensembles of myosin Va are able to transport fluid-state DOPC vesicles at velocities significantly faster (>700 nm/s) than a single motor. To explain these data, we developed a Monte Carlo simulation that suggests that these reductions in velocity can be attributed to two distinct mechanisms of intermotor interference (i.e., load-dependent modulation of stepping kinetics and binding-site exclusion), whereas faster transport velocities are consistent with a model wherein the normal stepping behavior of the myosin is supplemented by the preferential detachment of the trailing motor from the actin track.
Collapse
|
12
|
Soppina V, Verhey KJ. The family-specific K-loop influences the microtubule on-rate but not the superprocessivity of kinesin-3 motors. Mol Biol Cell 2014; 25:2161-70. [PMID: 24850887 PMCID: PMC4091829 DOI: 10.1091/mbc.e14-01-0696] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The kinesin-3 family–specific, positively charged insert, the K-loop, in loop 12 of the motor domain plays a critical role in cargo transport by enhancing the initial interaction of cargo-bound dimeric motors with the microtubule. The replacement of the K-loop, however, does not abolish the superprocessive motion of this class of kinesin motors. The kinesin-3 family (KIF) is one of the largest among the kinesin superfamily and an important driver of a variety of cellular transport events. Whereas all kinesins contain the highly conserved kinesin motor domain, different families have evolved unique motor features that enable different mechanical and functional outputs. A defining feature of kinesin-3 motors is the presence of a positively charged insert, the K-loop, in loop 12 of their motor domains. However, the mechanical and functional output of the K-loop with respect to processive motility of dimeric kinesin-3 motors is unknown. We find that, surprisingly, the K-loop plays no role in generating the superprocessive motion of dimeric kinesin-3 motors (KIF1, KIF13, and KIF16). Instead, we find that the K-loop provides kinesin-3 motors with a high microtubule affinity in the motor's ADP-bound state, a state that for other kinesins binds only weakly to the microtubule surface. A high microtubule affinity results in a high landing rate of processive kinesin-3 motors on the microtubule surface. We propose that the family-specific K-loop contributes to efficient kinesin-3 cargo transport by enhancing the initial interaction of dimeric motors with the microtubule track.
Collapse
Affiliation(s)
- Virupakshi Soppina
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109
| |
Collapse
|
13
|
Elfrink K, Liao W, Pieper U, Oeding SJ, Bähler M. The loop2 insertion of type IX myosin acts as an electrostatic actin tether that permits processive movement. PLoS One 2014; 9:e84874. [PMID: 24416302 PMCID: PMC3887004 DOI: 10.1371/journal.pone.0084874] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 11/19/2013] [Indexed: 11/19/2022] Open
Abstract
Although class IX myosins are single-headed, they demonstrate characteristics of processive movement along actin filaments. Double-headed myosins that move processively along actin filaments achieve this by successive binding of the two heads in a hand-over-hand mechanism. This mechanism, obviously, cannot operate in single-headed myosins. However, it has been proposed that a long class IX specific insertion in the myosin head domain at loop2 acts as an F-actin tether, allowing for single-headed processive movement. Here, we tested this proposal directly by analysing the movement of deletion constructs of the class IX myosin from Caenorhabditis elegans (Myo IX). Deletion of the large basic loop2 insertion led to a loss of processive behaviour, while deletion of the N-terminal head extension, a second unique domain of class IX myosins, did not influence the motility of Myo IX. The processive behaviour of Myo IX is also abolished with increasing salt concentrations. These observations directly demonstrate that the insertion located in loop2 acts as an electrostatic actin tether during movement of Myo IX along the actin track.
Collapse
Affiliation(s)
- Kerstin Elfrink
- Institute of Molecular Cell Biology, Westfalian Wilhelms-University, Muenster, Germany
| | - Wanqin Liao
- Institute of Molecular Cell Biology, Westfalian Wilhelms-University, Muenster, Germany
| | - Uwe Pieper
- Institute of Molecular Cell Biology, Westfalian Wilhelms-University, Muenster, Germany
| | - Stefanie J. Oeding
- Institute of Molecular Cell Biology, Westfalian Wilhelms-University, Muenster, Germany
| | - Martin Bähler
- Institute of Molecular Cell Biology, Westfalian Wilhelms-University, Muenster, Germany
- * E-mail:
| |
Collapse
|
14
|
Yuan J, Pillarisetti A, Goldman YE, Bau HH. Orienting actin filaments for directional motility of processive myosin motors. NANO LETTERS 2013; 13:79-84. [PMID: 23240631 DOI: 10.1021/nl303500k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
To utilize molecular motors in manmade systems, it is necessary to control the motors' motion. We describe a technique to orient actin filaments so that their barbed ends point in the same direction, enabling same-type motors to travel unidirectionally. Myosin-V and myosin-VI were observed to travel, respectively, toward and away from the filaments' barbed ends. When both motors were present, they occasionally passed each other while "walking" in opposite directions along single actin filaments.
Collapse
Affiliation(s)
- Jinzhou Yuan
- Department of Mechanical Engineering and Applied Mechanics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | | | |
Collapse
|
15
|
Goodman BS, Derr ND, Reck-Peterson SL. Engineered, harnessed, and hijacked: synthetic uses for cytoskeletal systems. Trends Cell Biol 2012; 22:644-52. [PMID: 23059001 DOI: 10.1016/j.tcb.2012.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 09/11/2012] [Accepted: 09/12/2012] [Indexed: 12/19/2022]
Abstract
Synthetic biology re-imagines existing biological systems by designing and constructing new biological parts, devices, and systems. In the arena of cytoskeleton-based transport, synthetic approaches are currently used in two broad ways. First, molecular motors are harnessed for non-physiological functions in cells. Second, transport systems are engineered in vitro to determine the biophysical rules that govern motility. These rules are then applied to synthetic nanotechnological systems. We review recent advances in both of these areas and conclude by discussing future directions in engineering the cytoskeleton and its motors for transport.
Collapse
Affiliation(s)
- Brian S Goodman
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | | | | |
Collapse
|
16
|
Hodges AR, Krementsova EB, Bookwalter CS, Fagnant PM, Sladewski TE, Trybus KM. Tropomyosin is essential for processive movement of a class V myosin from budding yeast. Curr Biol 2012; 22:1410-6. [PMID: 22704989 DOI: 10.1016/j.cub.2012.05.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 04/18/2012] [Accepted: 05/16/2012] [Indexed: 11/17/2022]
Abstract
Myosin V is an actin-based motor protein involved in intracellular cargo transport [1]. Given this physiological role, it was widely assumed that all class V myosins are processive, able to take multiple steps along actin filaments without dissociating. This notion was challenged when several class V myosins were characterized as nonprocessive in vitro, including Myo2p, the essential class V myosin from S. cerevisiae [2-6]. Myo2p moves cargo including secretory vesicles and other organelles for several microns along actin cables in vivo. This demonstrated cargo transporter must therefore either operate in small ensembles or behave processively in the cellular context. Here we show that Myo2p moves processively in vitro as a single motor when it walks on an actin track that more closely resembles the actin cables found in vivo. The key to processivity is tropomyosin: Myo2p is not processive on bare actin but highly processive on actin-tropomyosin. The major yeast tropomyosin isoform, Tpm1p, supports the most robust processivity. Tropomyosin slows the rate of MgADP release, thus increasing the time the motor spends strongly attached to actin. This is the first example of tropomyosin switching a motor from nonprocessive to processive motion on actin.
Collapse
Affiliation(s)
- Alex R Hodges
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA
| | | | | | | | | | | |
Collapse
|
17
|
Krementsova EB, Hodges AR, Bookwalter CS, Sladewski TE, Travaglia M, Sweeney HL, Trybus KM. Two single-headed myosin V motors bound to a tetrameric adapter protein form a processive complex. ACTA ACUST UNITED AC 2012; 195:631-41. [PMID: 22084309 PMCID: PMC3257522 DOI: 10.1083/jcb.201106146] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myo4p, one of two class V myosins in budding yeast, continuously transports messenger RNA (mRNA) cargo in the cell but is nonprocessive when characterized in vitro. The adapter protein She3p tightly binds to the Myo4p rod, forming a single-headed motor complex. In this paper, we show that two Myo4p-She3p motors are recruited by the tetrameric mRNA-binding protein She2p to form a processive double-headed complex. The binding site for She3p was mapped to a single α helix that protrudes at right angles from She2p. Processive runs of several micrometers on yeast actin-tropomyosin filaments were observed only in the presence of She2p, and, thus, motor activity is regulated by cargo binding. While moving processively, each head steps ~72 nm in a hand-over-hand motion. Coupling two high-duty cycle monomeric motors via a common cargo-binding adapter protein creates a complex with transport properties comparable with a single dimeric processive motor such as vertebrate myosin Va.
Collapse
Affiliation(s)
- Elena B Krementsova
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA
| | | | | | | | | | | | | |
Collapse
|
18
|
Tominaga M, Nakano A. Plant-Specific Myosin XI, a Molecular Perspective. FRONTIERS IN PLANT SCIENCE 2012; 3:211. [PMID: 22973289 PMCID: PMC3437519 DOI: 10.3389/fpls.2012.00211] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 08/21/2012] [Indexed: 05/04/2023]
Abstract
In eukaryotic cells, organelle movement, positioning, and communications are critical for maintaining cellular functions and are highly regulated by intracellular trafficking. Directional movement of motor proteins along the cytoskeleton is one of the key regulators of such trafficking. Most plants have developed a unique actin-myosin system for intracellular trafficking. Although the composition of myosin motors in angiosperms is limited to plant-specific myosin classes VIII and XI, there are large families of myosins, especially in class XI, suggesting functional diversification among class XI members. However, the molecular properties and regulation of each myosin XI member remains unclear. To achieve a better understanding of the plant-specific actin-myosin system, the characterization of myosin XI members at the molecular level is essential. In the first half of this review, we summarize the molecular properties of tobacco 175-kDa myosin XI, and in the later half, we focus on myosin XI members in Arabidopsis thaliana. Through detailed comparison of the functional domains of these myosins with the functional domain of myosin V, we look for possible diversification in enzymatic and mechanical properties among myosin XI members concomitant with their regulation.
Collapse
Affiliation(s)
- Motoki Tominaga
- Molecular Membrane Biology Laboratory, RIKEN Advanced Science InstituteWako, Saitama, Japan
- Japan Science and Technology Agency, PRESTOKawaguchi, Saitama, Japan
- *Correspondence: Motoki Tominaga, Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. e-mail:
| | - Akihiko Nakano
- Molecular Membrane Biology Laboratory, RIKEN Advanced Science InstituteWako, Saitama, Japan
- Department of Biological Sciences, Graduate School of Science, University of TokyoBunkyo-ku, Tokyo, Japan
| |
Collapse
|
19
|
McVicker DP, Chrin LR, Berger CL. The nucleotide-binding state of microtubules modulates kinesin processivity and the ability of Tau to inhibit kinesin-mediated transport. J Biol Chem 2011; 286:42873-80. [PMID: 22039058 DOI: 10.1074/jbc.m111.292987] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ability of Tau to act as a potent inhibitor of kinesin's processive run length in vitro suggests that it may actively participate in the regulation of axonal transport in vivo. However, it remains unclear how kinesin-based transport could then proceed effectively in neurons, where Tau is expressed at high levels. One potential explanation is that Tau, a conformationally dynamic protein, has multiple modes of interaction with the microtubule, not all of which inhibit kinesin's processive run length. Previous studies support the hypothesis that Tau has at least two modes of interaction with microtubules, but the mechanisms by which Tau adopts these different conformations and their functional consequences have not been investigated previously. In the present study, we have used single molecule imaging techniques to demonstrate that Tau inhibits kinesin's processive run length in an isoform-dependent manner on GDP-microtubules stabilized with either paclitaxel or glycerol/DMSO but not guanosine-5'-((α,β)-methyleno)triphosphate (GMPCPP)-stabilized microtubules. Furthermore, the order of Tau addition to microtubules before or after polymerization has no effect on the ability of Tau to modulate kinesin motility regardless of the stabilizing agent used. Finally, the processive run length of kinesin is reduced on GMPCPP-microtubules relative to GDP-microtubules, and kinesin's velocity is enhanced in the presence of 4-repeat long Tau but not the 3-repeat short isoform. These results shed new light on the potential role of Tau in the regulation of axonal transport, which is more complex than previously recognized.
Collapse
Affiliation(s)
- Derrick P McVicker
- Cell and Molecular Biology Program, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
| | | | | |
Collapse
|
20
|
Zimmermann D, Abdel Motaal B, Voith von Voithenberg L, Schliwa M, Ökten Z. Diffusion of myosin V on microtubules: a fine-tuned interaction for which E-hooks are dispensable. PLoS One 2011; 6:e25473. [PMID: 21966532 PMCID: PMC3180451 DOI: 10.1371/journal.pone.0025473] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 09/05/2011] [Indexed: 01/15/2023] Open
Abstract
Organelle transport in eukaryotes employs both microtubule and actin tracks to deliver cargo effectively to their destinations, but the question of how the two systems cooperate is still largely unanswered. Recently, in vitro studies revealed that the actin-based processive motor myosin V also binds to, and diffuses along microtubules. This biophysical trick enables cells to exploit both tracks for the same transport process without switching motors. The detailed mechanisms underlying this behavior remain to be solved. By means of single molecule Total Internal Reflection Microscopy (TIRFM), we show here that electrostatic tethering between the positively charged loop 2 and the negatively charged C-terminal E-hooks of microtubules is dispensable. Furthermore, our data indicate that in addition to charge-charge interactions, other interaction forces such as non-ionic attraction might account for myosin V diffusion. These findings provide evidence for a novel way of myosin tethering to microtubules that does not interfere with other E-hook-dependent processes.
Collapse
Affiliation(s)
- Dennis Zimmermann
- Institute for Anatomy and Cell Biology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Basma Abdel Motaal
- Institute for Anatomy and Cell Biology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | | | - Manfred Schliwa
- Institute for Anatomy and Cell Biology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Zeynep Ökten
- Institute for Anatomy and Cell Biology, Ludwig-Maximilians-University of Munich, Munich, Germany
- * E-mail:
| |
Collapse
|
21
|
Stark BC, Wen KK, Allingham JS, Rubenstein PA, Lord M. Functional adaptation between yeast actin and its cognate myosin motors. J Biol Chem 2011; 286:30384-30392. [PMID: 21757693 PMCID: PMC3162397 DOI: 10.1074/jbc.m111.262899] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 06/20/2011] [Indexed: 11/06/2022] Open
Abstract
We employed budding yeast and skeletal muscle actin to examine the contribution of the actin isoform to myosin motor function. While yeast and muscle actin are highly homologous, they exhibit different charge density at their N termini (a proposed myosin-binding interface). Muscle myosin-II actin-activated ATPase activity is significantly higher with muscle versus yeast actin. Whether this reflects inefficiency in the ability of yeast actin to activate myosin is not known. Here we optimized the isolation of two yeast myosins to assess actin function in a homogenous system. Yeast myosin-II (Myo1p) and myosin-V (Myo2p) accommodate the reduced N-terminal charge density of yeast actin, showing greater activity with yeast over muscle actin. Increasing the number of negative charges at the N terminus of yeast actin from two to four (as in muscle) had little effect on yeast myosin activity, while other substitutions of charged residues at the myosin interface of yeast actin reduced activity. Thus, yeast actin functions most effectively with its native myosins, which in part relies on associations mediated by its outer domain. Compared with yeast myosin-II and myosin-V, muscle myosin-II activity was very sensitive to salt. Collectively, our findings suggest differing degrees of reliance on electrostatic interactions during weak actomyosin binding in yeast versus muscle. Our study also highlights the importance of native actin isoforms when considering the function of myosins.
Collapse
Affiliation(s)
- Benjamin C Stark
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, Vermont 05405
| | - Kuo-Kuang Wen
- Department of Biochemistry, University of Iowa College of Medicine, Iowa City, Iowa 52242
| | - John S Allingham
- Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Peter A Rubenstein
- Department of Biochemistry, University of Iowa College of Medicine, Iowa City, Iowa 52242
| | - Matthew Lord
- Department of Molecular Physiology & Biophysics, University of Vermont, Burlington, Vermont 05405.
| |
Collapse
|
22
|
Nelson SR, Ali MY, Warshaw DM. Quantum dot labeling strategies to characterize single-molecular motors. Methods Mol Biol 2011; 778:111-21. [PMID: 21809203 DOI: 10.1007/978-1-61779-261-8_8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Recent advances in single-molecule labeling and detection techniques allow high-resolution imaging of the motion of single molecules. Molecular motors are biological machines that convert chemical energy into mechanical work. Myosin Va (MyoVa) is a well-characterized processive molecular motor, essential for cargo transport in living organisms. Quantum dots (Qdots) are fluorescent semiconductor nanocrystals that are extremely useful for single-molecule studies in biological sciences. High-resolution video microscopy and single-particle tracking of a Qdot-labeled MyoVa motor molecule allow the detection of individual steps in vitro and in live cells.
Collapse
Affiliation(s)
- Shane R Nelson
- Department of Molecular Physiology and Biophysics, University of Vermont College of Medicine, Burlington, VT, USA.
| | | | | |
Collapse
|
23
|
Liao W, Elfrink K, Bähler M. Head of myosin IX binds calmodulin and moves processively toward the plus-end of actin filaments. J Biol Chem 2010; 285:24933-42. [PMID: 20538589 DOI: 10.1074/jbc.m110.101105] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian myosin IXb (Myo9b) has been shown to exhibit unique motor properties in that it is a single-headed processive motor and the rate-limiting step in its chemical cycle is ATP hydrolysis. Furthermore, it has been reported to move toward the minus- and the plus-end of actin filaments. To analyze the contribution of the light chain-binding domain to the movement, processivity, and directionality of a single-headed processive myosin, we expressed constructs of Caenorhabditis elegans myosin IX (Myo9) containing either the head (Myo9-head) or the head and the light chain-binding domain (Myo9-head-4IQ). Both constructs supported actin filament gliding and moved toward the plus-end of actin filaments. We identified in the head of class IX myosins a calmodulin-binding site at the N terminus of loop 2 that is unique among the myosin superfamily members. Ca(2+)/calmodulin negatively regulated ATPase and motility of the Myo9-head. The Myo9-head demonstrated characteristics of a processive motor in that it supported actin filament gliding and pivoting at low motor densities. Quantum dot-labeled Myo9-head moved along actin filaments with a considerable run length and frequently paused without dissociating even in the presence of obstacles. We conclude that class IX myosins are plus-end-directed motors and that even a single head exhibits characteristics of a processive motor.
Collapse
Affiliation(s)
- Wanqin Liao
- Institute of Molecular Cell Biology, Westfalian Wilhelms-University, 48149 Münster, Germany
| | | | | |
Collapse
|
24
|
Abstract
For many viruses, the ability to infect eukaryotic cells depends on their transport through the cytoplasm and across the nuclear membrane of the host cell. During this journey, viral contents are biochemically processed into complexes capable of both nuclear penetration and genomic integration. We develop a stochastic model of viral entry that incorporates all relevant aspects of transport, including convection along microtubules, biochemical conversion, degradation, and nuclear entry. Analysis of the nuclear infection probabilities in terms of the transport velocity, degradation, and biochemical conversion rates shows how certain values of key parameters can maximize the nuclear entry probability of the viral material. The existence of such "optimal" infection scenarios depends on the details of the biochemical conversion process and implies potentially counterintuitive effects in viral infection, suggesting new avenues for antiviral treatment. Such optimal parameter values provide a plausible transport-based explanation of the action of restriction factors and of experimentally observed optimal capsid stability. Finally, we propose a new interpretation of how genetic mutations unrelated to the mechanism of drug action may nonetheless confer novel types of overall drug resistance.
Collapse
Affiliation(s)
- Maria R. D'Orsogna
- Department of Mathematics, California State University Northridge, Los Angeles, California, United States of America
| | - Tom Chou
- Department of Biomathematics and Department of Mathematics, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
| |
Collapse
|
25
|
Hodges AR, Bookwalter CS, Krementsova EB, Trybus KM. A nonprocessive class V myosin drives cargo processively when a kinesin- related protein is a passenger. Curr Biol 2009; 19:2121-5. [PMID: 20005107 DOI: 10.1016/j.cub.2009.10.069] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 10/14/2009] [Accepted: 10/22/2009] [Indexed: 11/29/2022]
Abstract
During secretory events, kinesin transports cargo along microtubules and then shifts control to myosin V for delivery on actin filaments to the cell membrane [1]. When kinesin and myosin V are present on the same cargo, kinesin interacts electrostatically with actin to enhance myosin V-based transport in vitro [2]. The relevance of this observation within the cell was questioned. In budding yeast, overexpression of a kinesin-family protein (Smy1p) suppressed a transport defect in a strain with a mutant class V myosin (Myo2p) [3]. We postulate that this is a cellular manifestation of the in vitro observation. We demonstrate that Smy1p binds electrostatically to actin bundles. Although a single Myo2p cannot transport cargo along actin bundles, addition of Smy1p causes the complex to undergo long-range, continuous movement. We propose that the kinesin-family protein acts as a tether that prevents cargo dissociation from actin, allowing the myosin to take many steps before dissociating. We demonstrate that both the tether and the motor reside on moving secretory vesicles in yeast cells, a necessary feature for this mechanism to apply in vivo. The presence of both kinesin and myosin on the same cargo may be a general mechanism to enhance cellular transport in yeast and higher organisms.
Collapse
Affiliation(s)
- Alex R Hodges
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA
| | | | | | | |
Collapse
|
26
|
Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin. Proc Natl Acad Sci U S A 2009; 106:21585-90. [PMID: 19955408 DOI: 10.1073/pnas.0910787106] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most myosins have a positively charged loop 2 with a cluster of lysine residues that bind to the negatively charged N-terminal segment of actin. However, the net charge of loop 2 of very fast Chara myosin is zero and there is no lysine cluster in it. In contrast, Chara myosin has a highly positively charged loop 3. To elucidate the role of these unique surface loops of Chara myosin in its high velocity and high actin-activated ATPase activity, we have undertaken mutational analysis using recombinant Chara myosin motor domain. It was found that net positive charge in loop 3 affected V(max) and K(app) of actin activated ATPase activity, while it affected the velocity only slightly. The net positive charge in loop 2 affected K(app) and the velocity, although it did not affect V(max). Our results suggested that Chara myosin has evolved to have highly positively charged loop 3 for its high ATPase activity and have less positively charged loop 2 for its high velocity. Since high positive charge in loop 3 and low positive charge in loop 2 seem to be one of the reasons for Chara myosin's high velocity, we manipulated charge contents in loops 2 and 3 of Dictyostelium myosin (class II). Removing positive charge from loop 2 and adding positive charge to loop 3 of Dictyostelium myosin made its velocity higher than that of the wild type, suggesting that the charge strategy in loops 2 and 3 is widely applicable.
Collapse
|
27
|
Bowling AP, Palmer AF, Wilhelm L. Contact and impact in the multibody dynamics of motor protein locomotion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12974-12981. [PMID: 19739622 DOI: 10.1021/la901812k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This paper presents the development of a rigid multibody dynamics approach to modeling, simulation, and analysis of motor proteins. A key element of this new model is that it retains the mass properties, in contrast to many commonly used models that do not. The mass properties are usually omitted because their inclusion yields a model with multiple time scales whose simulation requires a significant amount of time. However, the proposed model can be numerically integrated in a reasonable amount of time. Thus this approach represents a new method for treating multiple scale models. In addition, retaining the mass properties allows a detailed study of contact and impact between the protein and substrate, which is critical for protein processivity. The new model also provides insights into the characteristics of the protein and its environment, specifically, the effective damping experienced by the protein moving through its fluid environment may be quite small yielding under or critically damped motion. This conclusion runs contrary to the widely accepted notion that the protein's motion is strictly over damped. Herein, the differences between the motion predicted by the old and new modeling approaches are compared using a simplified model of Myosin V.
Collapse
Affiliation(s)
- Alan P Bowling
- Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, Texas 76019, USA.
| | | | | |
Collapse
|
28
|
Kubota H, Mikhailenko SV, Okabe H, Taguchi H, Ishiwata S. D-loop of actin differently regulates the motor function of myosins II and V. J Biol Chem 2009; 284:35251-8. [PMID: 19840951 DOI: 10.1074/jbc.m109.013565] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To gain more information on the manner of actin-myosin interaction, we examined how the motile properties of myosins II and V are affected by the modifications of the DNase I binding loop (D-loop) of actin, performed in two different ways, namely, the proteolytic digestion with subtilisin and the M47A point mutation. In an in vitro motility assay, both modifications significantly decreased the gliding velocity on myosin II-heavy meromyosin due to a weaker generated force but increased it on myosin V. On the other hand, single molecules of myosin V "walked" with the same velocity on both the wild-type and modified actins; however, the run lengths decreased sharply, correlating with a lower affinity of myosin for actin due to the D-loop modifications. The difference between the single-molecule and the ensemble measurements with myosin V indicates that in an in vitro motility assay the non-coordinated multiple myosin V molecules impose internal friction on each other via binding to the same actin filament, which is reduced by the weaker binding to the modified actins. These results show that the D-loop strongly modulates the force generation by myosin II and the processivity of myosin V, presumably affecting actin-myosin interaction in the actomyosin-ADP.P(i) state of both myosins.
Collapse
Affiliation(s)
- Hiroaki Kubota
- Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku,Tokyo, Japan
| | | | | | | | | |
Collapse
|
29
|
Abstract
Although myosin VI has properties that would allow it to function optimally as a dimer, full-length myosin VI exists as a monomer in isolation. Based on the ability of myosin VI monomers to dimerize when held in close proximity, we postulated that cargo binding normally regulates dimerization of myosin VI. We tested this hypothesis by expressing a known dimeric cargo adaptor protein of myosin VI, optineurin, and the myosin VI-binding segment from a monomeric cargo adaptor protein, Dab2. In the presence of these adaptor proteins, full-length myosin VI has ATPase properties of a dimer, appears as a dimer in electron micrographs, and moves processively on actin filaments. The results support a model in which cargo binding exposes internal dimerization sequences within full-length myosin VI. Because, unexpectedly, a monomeric fragment of Dab2 triggers dimerization, it would appear that myosin VI is designed to function as a dimer in cells.
Collapse
|
30
|
Nelson SR, Ali MY, Trybus KM, Warshaw DM. Random walk of processive, quantum dot-labeled myosin Va molecules within the actin cortex of COS-7 cells. Biophys J 2009; 97:509-18. [PMID: 19619465 DOI: 10.1016/j.bpj.2009.04.052] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2009] [Revised: 04/16/2009] [Accepted: 04/21/2009] [Indexed: 01/02/2023] Open
Abstract
Myosin Va (myoVa) is an actin-based intracellular cargo transporter. In vitro experiments have established that a single myoVa moves processively along actin tracks, but less is known about how this motor operates within cells. Here we track the movement of a quantum dot (Qdot)-labeled myoVa HMM in COS-7 cells using total internal reflectance fluorescence microscopy. This labeling approach is unique in that it allows myoVa, instead of its cargo, to be tracked. Single-particle analysis showed short periods (</=0.5 s) of ATP-sensitive linear motion. The mean velocity of these trajectories was 604 nm/s and independent of the number of myoVa molecules attached to the Qdot. With high time (16.6 ms) and spatial (15 nm) resolution imaging, Qdot-labeled myoVa moved with sequential 75 nm steps per head, at a rate of 16 s(-1), similarly to myoVa in vitro. Monte Carlo modeling suggests that the random nature of the trajectories represents processive myoVa motors undergoing a random walk through the dense and randomly oriented cortical actin network.
Collapse
Affiliation(s)
- Shane R Nelson
- Department of Molecular Physiology and Biophysics, University of Vermont College of Medicine, Burlington, Vermont, USA
| | | | | | | |
Collapse
|
31
|
Lu H, Ali MY, Bookwalter CS, Warshaw DM, Trybus KM. Diffusive movement of processive kinesin-1 on microtubules. Traffic 2009; 10:1429-38. [PMID: 19682327 DOI: 10.1111/j.1600-0854.2009.00964.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The processive motor kinesin-1 moves unidirectionally toward the plus end of microtubules. This process can be visualized by total internal reflection fluorescence microscopy of kinesin bound to a carboxylated quantum dot (Qdot), which acts both as cargo and label. Surprisingly, when kinesin is bound to an anti-HIS Qdot, it shows diffusive movement on microtubules, which decreased in favor of processive runs with increasing salt concentration. This observation implies that kinesin movement on microtubules is governed by its conformation, as it is well established that kinesin undergoes a salt-dependent transition from a folded (inactive) to an extended (active) molecule. A truncated kinesin lacking the last 75 amino acids (kinesin-Delta C) showed both processive and diffusive movement on microtubules. The extent of each behavior depends on the relative amounts of ADP and ATP, with purely diffusive movement occurring in ADP alone. Taken together, these data imply that folded kinesin.ADP can exist in a state that diffuses along the microtubule lattice without expending energy. This mechanism may facilitate the ability of kinesin to pick up cargo, and/or allow the kinesin/cargo complex to stay bound after encountering obstacles.
Collapse
Affiliation(s)
- Hailong Lu
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA
| | | | | | | | | |
Collapse
|
32
|
Walcott S, Fagnant PM, Trybus KM, Warshaw DM. Smooth muscle heavy meromyosin phosphorylated on one of its two heads supports force and motion. J Biol Chem 2009; 284:18244-51. [PMID: 19419961 DOI: 10.1074/jbc.m109.003293] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Smooth muscle myosin is activated by regulatory light chain (RLC) phosphorylation. In the unphosphorylated state the activity of both heads is suppressed due to an asymmetric, intramolecular interaction between the heads. The properties of myosin with only one of its two RLCs phosphorylated, a state likely to be present both during the activation and the relaxation phase of smooth muscle, is less certain despite much investigation. Here we further characterize the mechanical properties of an expressed heavy meromyosin (HMM) construct with only one of its RLCs phosphorylated (HMM-1P). This construct was previously shown to have more than 50% of the ATPase activity of fully phosphorylated myosin (HMM-2P) and to move actin at the same speed in a motility assay as HMM-2P (Rovner, A. S., Fagnant, P. M., and Trybus, K. M. (2006) Biochemistry 45, 5280-5289). Here we show that the unitary step size and attachment time to actin of HMM-1P is indistinguishable from that of HMM-2P. Force-velocity measurements on small ensembles show that HMM-1P can generate approximately half the force of HMM-2P, which may relate to the observed duty ratio of HMM-1P being approximately half that of HMM-2P. Therefore, single-phosphorylated smooth muscle HMM molecules are active species, and the head associated with the unphosphorylated RLC is mechanically competent, allowing it to make a substantial contribution to both motion and force generation during smooth muscle contraction.
Collapse
Affiliation(s)
- Sam Walcott
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | | | | | | |
Collapse
|
33
|
Higashi-Fujime S, Nakamura A. Cell and molecular biology of the fastest myosins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:301-47. [PMID: 19584016 DOI: 10.1016/s1937-6448(09)76007-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Chara myosin is a class XI plant myosin in green algae Chara corallina and responsible for fast cytoplasmic streaming. The Chara myosin exhibits the fastest sliding movement of F-actin at 60 mum/s as observed so far, 10-fold of the shortening speed of muscle. It has some distinct properties differing from those of muscle myosin. Although knowledge about Chara myosin is very limited at present, we have tried to elucidate functional bases of its characteristics by comparing with those of other myosins. In particular, we have built the putative atomic model of Chara myosin by using the homology-based modeling system and databases. Based on the putative structure of Chara myosin obtained, we have analyzed the relationship between structure and function of Chara myosin to understand its distinct properties from various aspects by referring to the accumulated knowledge on mechanochemical and structural properties of other classes of myosin, particularly animal and fungal myosin V. We will also discuss the functional significance of Chara myosin in a living cell.
Collapse
Affiliation(s)
- Sugie Higashi-Fujime
- Department of Molecular and Cellular Pharmacology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | | |
Collapse
|
34
|
Abstract
Myosin V (myoV), a processive cargo transporter, has arguably been the most well-studied unconventional myosin of the past decade. Considerable structural information is available for the motor domain, the IQ motifs with bound calmodulin or light chains, and the cargo-binding globular tail, all of which have been crystallized. The repertoire of adapter proteins that link myoV to a particular cargo is becoming better understood, enabling cellular transport processes to be dissected. MyoV is processive, meaning that it takes many steps on actin filaments without dissociating. Its extended lever arm results in long 36-nm steps, making it ideal for single molecule studies of processive movement. In addition, electron microscopy revealed the structure of the inactive, folded conformation of myoV when it is not transporting cargo. This review provides a background on myoV, and highlights recent discoveries that show why myoV will continue to be an active focus of investigation.
Collapse
Affiliation(s)
- K M Trybus
- Department of Molecular Physiology and Biophysics, 149 Beaumont Avenue, University of Vermont, Burlington, Vermont 05405, USA.
| |
Collapse
|
35
|
Myosin V and Kinesin act as tethers to enhance each others' processivity. Proc Natl Acad Sci U S A 2008; 105:4691-6. [PMID: 18347333 DOI: 10.1073/pnas.0711531105] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Organelle transport to the periphery of the cell involves coordinated transport between the processive motors kinesin and myosin V. Long-range transport takes place on microtubule tracks, whereas final delivery involves shorter actin-based movements. The concept that motors only function on their appropriate track required further investigation with the recent observation that myosin V undergoes a diffusional search on microtubules. Here we show, using single-molecule techniques, that a functional consequence of myosin V's diffusion on microtubules is a significant enhancement of the processive run length of kinesin when both motors are present on the same cargo. The degree of run length enhancement correlated with the net positive charge in loop 2 of myosin V. On actin, myosin V also undergoes longer processive runs when kinesin is present on the same cargo. The process that causes run length enhancement on both cytoskeletal tracks is electrostatic. We propose that one motor acts as a tether for the other and prevents its diffusion away from the track, thus allowing more steps to be taken before dissociation. The resulting run length enhancement likely contributes to the successful delivery of cargo in the cell.
Collapse
|
36
|
Hodges AR, Krementsova EB, Trybus KM. She3p binds to the rod of yeast myosin V and prevents it from dimerizing, forming a single-headed motor complex. J Biol Chem 2008; 283:6906-14. [PMID: 18175803 DOI: 10.1074/jbc.m708865200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vertebrate myosin Va is a dimeric processive motor that walks on actin filaments to deliver cargo. In contrast, the two class V myosins in budding yeast, Myo2p and Myo4p, are non-processive (Reck-Peterson, S. L., Tyska, M. J., Novick, P. J., and Mooseker, M. S. (2001) J. Cell Biol. 153, 1121-1126). We previously showed that a chimera with the motor domain of Myo4p on the backbone of vertebrate myosin Va was processive, demonstrating that the Myo4p motor domain has a high duty ratio. Here we examine the properties of a chimera containing the rod and globular tail of Myo4p joined to the motor domain and neck of mouse myosin Va. Surprisingly, the adaptor protein She3p binds to the rod region of Myo4p and forms a homogeneous single-headed myosin-She3p complex, based on sedimentation equilibrium and velocity data. We propose that She3p forms a heterocoiled-coil with Myo4p and is a subunit of the motor. She3p does not affect the maximal actin-activated ATPase in solution or the velocity of movement in an ensemble in vitro motility assay. At the single molecule level, the monomeric myosin-She3p complex showed no processivity. When this construct was dimerized with a leucine zipper, short processive runs were obtained. Robust continuous movement was observed when multiple monomeric myosin-She3p motors were bound to a quantum dot "cargo." We propose that continuous transport of mRNA by Myo4p-She3p in yeast is accomplished either by multiple high duty cycle monomers or by molecules that may be dimerized by She2p, the homodimeric downstream binding partner of She3p.
Collapse
Affiliation(s)
- Alex R Hodges
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405, USA
| | | | | |
Collapse
|