101
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Tomishige M, Stuurman N, Vale RD. Single-molecule observations of neck linker conformational changes in the kinesin motor protein. Nat Struct Mol Biol 2006; 13:887-94. [PMID: 17013387 DOI: 10.1038/nsmb1151] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 09/05/2006] [Indexed: 11/08/2022]
Abstract
Kinesin-1 is a dimeric motor protein that moves cargo processively along microtubules. Kinesin motility has been proposed to be driven by the coordinated forward extension of the neck linker (a approximately 12-residue peptide) in one motor domain and the rearward positioning of the neck linker in the partner motor domain. To test this model, we have introduced fluorescent dyes selectively into one subunit of the kinesin dimer and performed 'half-molecule' fluorescence resonance energy transfer to measure conformational changes of the neck linker. We show that when kinesin binds with both heads to the microtubule, the neck linkers in the rear and forward heads extend forward and backward, respectively. During ATP-driven motility, the neck linkers switch between these conformational states. These results support the notion that neck linker movements accompany the 'hand-over-hand' motion of the two motor domains.
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Affiliation(s)
- Michio Tomishige
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
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102
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Schaffner SC, José JV. Biophysical model of self-organized spindle formation patterns without centrosomes and kinetochores. Proc Natl Acad Sci U S A 2006; 103:11166-71. [PMID: 16844776 PMCID: PMC1544059 DOI: 10.1073/pnas.0604721103] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic cell division and chromosome segregation depend crucially on the mitotic spindle pattern formation. The usual pathway for spindle production involves microtubule polymerization from two centrosomes. However, experiments using Xenopus extracts with micrometer-sized chromatin-coated beads found, remarkably, that spindle patterns can form in the absence of centrosomes, kinetochores, and duplicated chromosomes. Here we introduce a previously undescribed biophysical model inspired by the heuristic interpretations of the experiments that provides a quantitative explanation and constraints for this type of experiment. The model involves plus-directed (chromokinesin and Eg5) and minus-directed (cytoplasmic dynein oligomers) motors walking on microtubules and the boundary conditions caused by the chromatin-coated spheres. This model combines the effects of the plus-directed cross-linking motor Eg5 and any chromokinesin on the chromatin-covered beads, reflecting current uncertainties in the division of function between the two kinds of motors. The model can nucleate dynamically a variety of self-organized spindle patterns over a wide range of biological parameter values. Our calculations show that spindles will form over a wide range of parameter values. Some parameter values cause a monaster to form instead of a bipolar spindle. Varying the processivity and the dynein microtubule attachment and detachment rates, we find stability parameters for spindle formations. These results not only constrain the possible parameter values, but they point toward the proper division of function between Eg5 and chromokinesin in this spindle formation pathway. The model results suggest experiments that would further enhance our understanding of the basic elements needed for spindle pattern formation in this pathway.
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Affiliation(s)
- Stuart C. Schaffner
- *Center for Interdisciplinary Research on Complex Systems and Physics Department, Northeastern University, 360 Huntington Avenue, Boston, MA 02115; and
| | - Jorge V. José
- *Center for Interdisciplinary Research on Complex Systems and Physics Department, Northeastern University, 360 Huntington Avenue, Boston, MA 02115; and
- Physics Department and Department of Physiology and Biophysics, 516 Capen Hall, University at Buffalo, State University of New York, Buffalo, NY 14260-1611
- To whom correspondence should be addressed. E-mail:
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103
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Abstract
A physically motivated model of kinesin's motor function is developed within the framework of rectified Brownian motion. The model explains how the amplification of neck linker zippering arises naturally through well-known formulae for overdamped dynamics, thereby providing a means to understand how weakly-favorable zippering leads to strongly favorable plus-directed binding of a free kinesin head to microtubule. Additional aspects of kinesin's motion, such as head coordination and rate-limiting steps, are directly related to the force-dependent inhibition of ATP binding to a microtubule bound head. The model of rectified Brownian motion is presented as an alternative to power stroke models and provides an alternative interpretation for the significance of ATP hydrolysis in the kinesin stepping cycle.
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Affiliation(s)
- William H Mather
- School of Physics and Center for Nonlinear Science, Georgia Institute of Technology, Atlanta, Georgia, USA
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104
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Asenjo AB, Weinberg Y, Sosa H. Nucleotide binding and hydrolysis induces a disorder-order transition in the kinesin neck-linker region. Nat Struct Mol Biol 2006; 13:648-54. [PMID: 16783374 DOI: 10.1038/nsmb1109] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Accepted: 05/15/2006] [Indexed: 11/09/2022]
Abstract
Kinesin translocation is thought to occur by a conformational change in a region of the motor domain called the neck linker. However, most evidence supporting this hypothesis comes from monomeric constructs unable to move processively. To address this issue, we investigated the neck-linker configuration on microtubule-bound monomeric and dimeric kinesin constructs using single-molecule fluorescence polarization microscopy. We found that the neck-linker region (i) is very mobile in the absence of nucleotides and during steady walking, (ii) decreases mobility and aligns along the microtubule axis in the presence of AMPPNP or ADP + AlF4(-), (iii) is mostly ordered in the monomeric constructs in the presence of ADP + AlF4(-), and (iv) is closer to parallel to the microtubule axis in the dimeric constructs. These results support the proposed role of the neck linker and suggest a coordination mechanism between the two motor domains in the dimer.
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Affiliation(s)
- Ana B Asenjo
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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105
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Guydosh NR, Block SM. Backsteps induced by nucleotide analogs suggest the front head of kinesin is gated by strain. Proc Natl Acad Sci U S A 2006; 103:8054-9. [PMID: 16698928 PMCID: PMC1472428 DOI: 10.1073/pnas.0600931103] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The two-headed kinesin motor harnesses the energy of ATP hydrolysis to take 8-nm steps, walking processively along a microtubule, alternately stepping with each of its catalytic heads in a hand-over-hand fashion. Two persistent challenges for models of kinesin motility are to explain how the two heads are coordinated ("gated") and when the translocation step occurs relative to other events in the mechanochemical reaction cycle. To investigate these questions, we used a precision optical trap to measure the single-molecule kinetics of kinesin in the presence of substrate analogs beryllium fluoride or adenylyl-imidodiphosphate. We found that normal stepping patterns were interspersed with long pauses induced by analog binding, and that these pauses were interrupted by short-lived backsteps. After a pause, processive stepping could only resume once the kinesin molecule took an obligatory, terminal backstep, exchanging the positions of its front and rear heads, presumably to allow release of the bound analog from the new front head. Preferential release from the front head implies that the kinetics of the two heads are differentially affected when both are bound to the microtubule, presumably by internal strain that is responsible for the gating. Furthermore, we found that ATP binding was required to reinitiate processive stepping after the terminal backstep. Together, our results support stepping models in which ATP binding triggers the mechanical step and the front head is gated by strain.
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Affiliation(s)
| | - Steven M. Block
- Biological Sciences and
- Applied Physics, Stanford University, Stanford, CA 94305
- To whom correspondence should be addressed. E-mail:
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106
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Hahlen K, Ebbing B, Reinders J, Mergler J, Sickmann A, Woehlke G. Feedback of the kinesin-1 neck-linker position on the catalytic site. J Biol Chem 2006; 281:18868-77. [PMID: 16682419 DOI: 10.1074/jbc.m508019200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kinesin-1 motor proteins step along microtubules by a mechanism in which the heads cycle through microtubule-bound and unbound states in an interlaced fashion. An important contribution to head-head coordination arises from the action of the neck-linker that docks onto the core motor domain upon ATP binding. We show here that the docked neck-linker not only guides the microtubule-unbound head to the next microtubule binding site but also signals its position to the head to which it is attached. Cross-linking studies on mutated kinesin constructs reveal that residues at the interface motor core/docked neck-linker, among them most importantly a conserved tyrosine, are involved in this feedback. The primary effect of the docked neck-linker is a reduced microtubule binding affinity in the ADP state.
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Affiliation(s)
- Katrin Hahlen
- Institute for Cell Biology, Ludwig-Maximilians University, Schillerstrasse 42, 80336 München, Germany
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107
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Xie P, Dou SX, Wang PY. Mechanochemical couplings of kinesin motors. Biophys Chem 2006; 123:58-76. [PMID: 16707205 DOI: 10.1016/j.bpc.2006.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 04/03/2006] [Accepted: 04/08/2006] [Indexed: 11/26/2022]
Abstract
Kinesins are molecular motors capable of moving processively along microtubule in a stepwise manner by hydrolyzing ATP. Numerous experimental results on various aspects of their dynamical behaviours are available in literature. Although a number of models of tightly coordinated mechanism have been proposed to explain some experimental results, up to now no good explanation has been given to all these experimental results by using a single model. We have recently proposed such a model of partially coordinated hand-over-hand moving mechanism. In this paper, we use this model to study in detail various aspects of the dynamical properties of single kinesin molecules. We show that kinesin dimers walk hand-over-hand along microtubules in a partially coordinated rather than a tightly coordinated manner. The degree of coordination depends on the ratio of the two heads' ATPase rates that are in turn determined by both internal elastic force and external load. We have tested this model using various available experimental results on different samples and obtained a good agreement between the theory and the experiments.
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Affiliation(s)
- Ping Xie
- Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
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108
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Xie P, Dou SX, Wang PY. Model for kinetics of wild-type and mutant kinesins. Biosystems 2006; 84:24-38. [PMID: 16378677 DOI: 10.1016/j.biosystems.2005.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 09/30/2005] [Accepted: 09/30/2005] [Indexed: 11/21/2022]
Abstract
A hand-over-hand model is presented for the processive movement of two-headed kinesin based on previous structural and biochemical studies. In the model, the ATPase activities of the two heads are regulated by forces, both from internal elasticity and external load, exerted on their neck linkers. The results from the model show that the two heads may be partially coordinated in their ATPase cycles: in the case of backward load or low forward load, the ATPase cycles of its two heads are well coordinated, whereas in the case of high forward load, they are no longer well coordinated. The model gives results that show good quantitative agreement with both previous biochemical and mechanical experimental results such as the limping of homodimers and the dependences of mean velocity on [ATP] and on loads (both positive and negative). Furthermore, using the model we study the kinetics of a number of mutant kinesin homodimers and heterodimers, showing that the two heads' ATPase activities of some of these molecules are not well coordinated and they move processively with low mechanochemical coupling efficiencies even under no load. The theoretical results of ATPase rate per head, moving velocity, and stall force of the motors show good quantitative agreement with the experimental ones. The puzzling dynamic behaviours of mutant homodimeric and heterodimeric kinesins become understandable.
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Affiliation(s)
- Ping Xie
- Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China.
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109
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110
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Adio S, Reth J, Bathe F, Woehlke G. Review: regulation mechanisms of Kinesin-1. J Muscle Res Cell Motil 2006; 27:153-60. [PMID: 16450053 DOI: 10.1007/s10974-005-9054-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Accepted: 12/08/2005] [Indexed: 01/16/2023]
Abstract
Kinesin-1 microtubule motors are common kinesin motors from protozoa, fungi and animals. They transport vesicular or particle cargo in a strictly regulated manner. The relatively well-studied tail inhibition mechanism is based on a conformational change that leads to an interaction of Kinesin-1's tail with the junction of neck and hinge regions. This folding causes a decrease in microtubule binding and motor activity. In fungal Kinesin-1 motors several lines of evidence suggest that a conserved tyrosine in the neck coiled-coil mediates this inhibition. In the active state, a region surrounding a conserved tryptophan in the hinge stabilises the neck coiled-coil, and prevents the tyrosine from inhibiting. Although animal and fungal Kinesin-1 motors are clearly homologous and function according to the same chemo-mechanical mechanism, they differ in their regulation. Unlike fungal Kinesin-1s, animal kinesins associate with light chains that are important for regulation and cargo interaction. Several proteins interacting with animal Kinesin-1 heavy or light chains are known, among them typical scaffolding proteins that seem to link Kinesin-1 to signalling pathways.
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Affiliation(s)
- Sarah Adio
- Institute for Cell Biology, University of Munich, Schillerstr. 42, D-80336, Munich, Germany
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111
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Seitz A, Surrey T. Processive movement of single kinesins on crowded microtubules visualized using quantum dots. EMBO J 2006; 25:267-77. [PMID: 16407972 PMCID: PMC1383520 DOI: 10.1038/sj.emboj.7600937] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 12/06/2005] [Indexed: 11/09/2022] Open
Abstract
Kinesin-1 is a processive molecular motor transporting cargo along microtubules. Inside cells, several motors and microtubule-associated proteins compete for binding to microtubules. Therefore, the question arises how processive movement of kinesin-1 is affected by crowding on the microtubule. Here we use total internal reflection fluorescence microscopy to image in vitro the runs of single quantum dot-labelled kinesins on crowded microtubules under steady-state conditions and to measure the degree of crowding on a microtubule at steady-state. We find that the runs of kinesins are little affected by high kinesin densities on a microtubule. However, the presence of high densities of a mutant kinesin that is not able to step efficiently reduces the average speed of wild-type kinesin, while hardly changing its processivity. This indicates that kinesin waits in a strongly bound state on the microtubule when encountering an obstacle until the obstacle unbinds and frees the binding site for kinesin's next step. A simple kinetic model can explain quantitatively the behaviour of kinesin under both crowding conditions.
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Affiliation(s)
- Arne Seitz
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Thomas Surrey
- European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Heidelberg, Germany
- EMBL, Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany. Tel.: +49 6221 387 8360; Fax: +49 6221 387 8512; E-mail:
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112
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Carter NJ, Cross RA. Kinesin's moonwalk. Curr Opin Cell Biol 2005; 18:61-7. [PMID: 16361092 DOI: 10.1016/j.ceb.2005.12.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 12/02/2005] [Indexed: 11/20/2022]
Abstract
Kinesin-1 is a single-molecule walking machine, driven by ATP turnover. Recent optical trapping experiments show that pulling backwards on a walking kinesin-1 molecule causes the mechanical walking action to reverse, while the coupled chemical cycle of ATP turnover continues, apparently, to run forwards -- kinesin can moonwalk. Individual forward- and back-steps are fast, and each appears to be a single event, complete in a few tens of microseconds, with no substeps. Between steps, kinesin pauses, waiting for the next ATP to arrive. Several lines of evidence indicate that during these between-step dwells, only one of the two heads is strongly attached to the microtubule. The position of the other head during the dwells is less certain, and more controversial.
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Affiliation(s)
- Nicholas J Carter
- Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey, RH8 0TE UK
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113
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Thomas W, Forero M, Yakovenko O, Nilsson L, Vicini P, Sokurenko E, Vogel V. Catch-bond model derived from allostery explains force-activated bacterial adhesion. Biophys J 2005; 90:753-64. [PMID: 16272438 PMCID: PMC1367101 DOI: 10.1529/biophysj.105.066548] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
High shear enhances the adhesion of Escherichia coli bacteria binding to mannose coated surfaces via the adhesin FimH, raising the question as to whether FimH forms catch bonds that are stronger under tensile mechanical force. Here, we study the length of time that E. coli pause on mannosylated surfaces and report a double exponential decay in the duration of the pauses. This double exponential decay is unlike previous single molecule or whole cell data for other catch bonds, and indicates the existence of two distinct conformational states. We present a mathematical model, derived from the common notion of chemical allostery, which describes the lifetime of a catch bond in which mechanical force regulates the transitions between two conformational states that have different unbinding rates. The model explains these characteristics of the data: a double exponential decay, an increase in both the likelihood and lifetime of the high-binding state with shear stress, and a biphasic effect of force on detachment rates. The model parameters estimated from the data are consistent with the force-induced structural changes shown earlier in FimH. This strongly suggests that FimH forms allosteric catch bonds. The model advances our understanding of both catch bonds and the role of allostery in regulating protein activity.
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Affiliation(s)
- Wendy Thomas
- Department of Bioengineering, University of Washington, Seattle, Washington, USA.
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114
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Abstract
The pathway of ATP hydrolysis by rat kinesin was established by pre-steady-state kinetic methods. A 406-residue long N-terminal fragment was shown by sedimentation equilibrium analysis to form a dimer with a K(d) of 46 nm. The pathway of ATP hydrolysis follows the Gilbert-Johnson pathway determined previously for a similarsized N-terminal fragment of Drosophila conventional kinesin. However, the rates of ADP release were at least 3-fold faster, and ATP hydrolysis was approximately 5-fold faster. Paralleling our previous mechanistic data, these results support an alternating site ATPase pathway, including a captive head state as an intermediate in the kinesin ATPase cycle. The kinetic data presented in this report once again point to the importance of the captive head state and argue against a pathway that short-circuits this key intermediate. In addition, several unique aspects of the rat kinesin kinetics reveal new aspects of the ATPase-coupling mechanism. These studies provide a baseline set of kinetic parameters against which future studies of rat kinesin mutants may be evaluated and directly correlated with the structure of the dimeric kinesin.
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Affiliation(s)
- Scott D Auerbach
- Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA
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115
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Rosenfeld SS, Xing J, Jefferson GM, King PH. Docking and rolling, a model of how the mitotic motor Eg5 works. J Biol Chem 2005; 280:35684-95. [PMID: 16115880 DOI: 10.1074/jbc.m506561200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whereas kinesin I is designed to transport cargoes long distances in isolation, a closely related kinesin motor, Eg5, is designed to generate a sustained opposing force necessary for proper mitotic spindle formation. Do the very different roles for these evolutionarily related motors translate into differences in how they generate movement? We have addressed this question by examining when in the ATPase cycle the Eg5 motor domain and neck linker move through the use of a series of novel spectroscopic probes utilizing fluorescence resonance energy transfer, and we have compared our results to kinesin I. Our results are consistent with a model in which movement in Eg5 occurs in two sequential steps, an ATP-dependent docking of the neck linker, followed by a rotation or "rolling" of the entire motor domain on the microtubule surface that occurs with ATP hydrolysis. These two forms of movement are consistent with the functions of a motor designed to generate sustained opposing force, and hence, our findings support the argument that the mechanochemical features of a molecular motor are shaped more by the demands placed on it than by its particular family of origin.
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Affiliation(s)
- Steven S Rosenfeld
- Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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116
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Lakämper S, Meyhöfer E. The E-hook of tubulin interacts with kinesin's head to increase processivity and speed. Biophys J 2005; 89:3223-34. [PMID: 16100283 PMCID: PMC1366818 DOI: 10.1529/biophysj.104.057505] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kinesins are dimeric motor proteins that move processively along microtubules. It has been proposed that the processivity of conventional kinesins is increased by electrostatic interactions between the positively charged neck of the motor and the negatively charged C-terminus of tubulin (E-hook). In this report we challenge this anchoring hypothesis by studying the motility of a fast fungal kinesin from Neurospora crassa (NcKin). NcKin is highly processive despite lacking the positive charges in the neck. We present a detailed analysis of how proteolytic removal of the E-hook affects truncated monomeric and dimeric constructs of NcKin. Upon digestion we observe a strong reduction of the processivity and speed of dimeric motor constructs. Monomeric motors with truncated or no neck display the same reduction of microtubule gliding speed as dimeric constructs, suggesting that the E-hook interacts with the head only. The E-hook has no effect on the strongly bound states of NcKin as microtubule digestion does not alter the stall forces produced by single dimeric motors, suggesting that the E-hook affects the interaction site of the kinesin.ADP-head and the microtubule. In fact, kinetic and binding experiments indicate that removal of the E-hook shifts the binding equilibrium of the weakly attached kinesin.ADP-head toward a more strongly bound state, which may explain reduced processivity and speed on digested microtubules.
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MESH Headings
- Adenosine Diphosphate/chemistry
- Adenosine Triphosphatases/chemistry
- Adenosine Triphosphate/chemistry
- Animals
- Binding Sites
- Biophysics/methods
- Biotinylation
- Blotting, Western
- Brain/metabolism
- Cattle
- Chromatography, Ion Exchange
- Cloning, Molecular
- Dimerization
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- Escherichia coli/metabolism
- Guanosine Triphosphate/chemistry
- Image Processing, Computer-Assisted
- Ions
- Kinesins/chemistry
- Kinetics
- Lasers
- Microscopy, Fluorescence
- Microtubules/chemistry
- Models, Biological
- Movement
- Neurospora crassa/metabolism
- Potassium/chemistry
- Protein Binding
- Protein Structure, Tertiary
- Proteins/chemistry
- Spectrometry, Fluorescence
- Static Electricity
- Tubulin/chemistry
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Affiliation(s)
- Stefan Lakämper
- Department of Mechanical Engineering, University of Michigan, 2350 Hayward, Ann Arbor, MI 48109, USA
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117
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Ménétrey J, Bahloul A, Wells A, Yengo C, Morris C, Sweeney HL, Houdusse A. The structure of the myosin VI motor reveals the mechanism of directionality reversal. Nature 2005; 435:779-85. [PMID: 15944696 PMCID: PMC2762700 DOI: 10.1038/nature03592] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 04/01/2005] [Indexed: 11/09/2022]
Abstract
Here we solve a 2.4-A structure of a truncated version of the reverse-direction myosin motor, myosin VI, that contains the motor domain and binding sites for two calmodulin molecules. The structure reveals only minor differences in the motor domain from that in plus-end directed myosins, with the exception of two unique inserts. The first is near the nucleotide-binding pocket and alters the rates of nucleotide association and dissociation. The second unique insert forms an integral part of the myosin VI converter domain along with a calmodulin bound to a novel target motif within the insert. This serves to redirect the effective 'lever arm' of myosin VI, which includes a second calmodulin bound to an 'IQ motif', towards the pointed (minus) end of the actin filament. This repositioning largely accounts for the reverse directionality of this class of myosin motors. We propose a model incorporating a kinesin-like uncoupling/docking mechanism to provide a full explanation of the movements of myosin VI.
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Affiliation(s)
- Julie Ménétrey
- Structural Motility, Institut Curie CNRS, UMR144, 26 rue d’Ulm, 75248 Paris cedex 05, France
| | - Amel Bahloul
- Structural Motility, Institut Curie CNRS, UMR144, 26 rue d’Ulm, 75248 Paris cedex 05, France
| | - Amber Wells
- Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085 USA
| | - Christopher Yengo
- Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085 USA
| | - Carl Morris
- Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085 USA
| | - H. Lee Sweeney
- Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085 USA
| | - Anne Houdusse
- Structural Motility, Institut Curie CNRS, UMR144, 26 rue d’Ulm, 75248 Paris cedex 05, France
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118
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Snyder GE, Sakamoto T, Hammer JA, Sellers JR, Selvin PR. Nanometer localization of single green fluorescent proteins: evidence that myosin V walks hand-over-hand via telemark configuration. Biophys J 2005; 87:1776-83. [PMID: 15345556 PMCID: PMC1304582 DOI: 10.1529/biophysj.103.036897] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myosin V is a homodimeric motor protein involved in trafficking of vesicles in the cell. It walks bipedally along actin filaments, moving cargo approximately 37 nm per step. We have measured the step size of individual myosin heads by fusing an enhanced green fluorescent protein (eGFP) to the N-terminus of one head of the myosin dimer and following the motion with nanometer precision and subsecond resolution. We find the average step size to be 74.1 nm with 9.4 nm (SD) and 0.3 nm (SE). Our measurements demonstrate nanometer localization of single eGFPs, confirm the hand-over-hand model of myosin V procession, and when combined with previous data, suggest that there is a kink in the leading lever arm in the waiting state of myosin V. This kink, or "telemark skier" configuration, may cause strain, which, when released, leads to the powerstroke of myosin, throwing the rear head forward and leading to unidirectional motion.
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Affiliation(s)
- Gregory E Snyder
- Physics Department and Center for Biophysics and Computational Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
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119
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Zhang Y, Hancock WO. The two motor domains of KIF3A/B coordinate for processive motility and move at different speeds. Biophys J 2004; 87:1795-804. [PMID: 15345558 PMCID: PMC1304584 DOI: 10.1529/biophysj.104.039842] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2004] [Accepted: 06/01/2004] [Indexed: 11/18/2022] Open
Abstract
KIF3A/B, a kinesin involved in intraflagellar transport and Golgi trafficking, is distinctive because it contains two nonidentical motor domains. Our hypothesis is that the two heads have distinct functional properties, which are tuned to maximize the performance of the wild-type heterodimer. To test this, we investigated the motility of wild-type KIF3A/B heterodimer and chimaeric KIF3A/A and KIF3B/B homodimers made by splicing the head of one subunit to the rod and tail of the other. The first result is that KIF3A/B is processive, consistent with its transport function in cells. Secondly, the KIF3B/B homodimer moves at twice the speed of the wild-type motor but has reduced processivity, suggesting a trade-off between speed and processivity. Third, the KIF3A/A homodimer moves fivefold slower than wild-type, demonstrating distinct functional differences between the two heads. The heterodimer speed cannot be accounted for by a sequential head model in which the two heads alternate along the microtubule with identical speeds as in the homodimers. Instead, the data are consistent with a coordinated head model in which detachment of the slow KIF3A head from the microtubule is accelerated roughly threefold by the KIF3B head.
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Affiliation(s)
- Yangrong Zhang
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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120
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Uemura S, Higuchi H, Olivares AO, De La Cruz EM, Ishiwata S. Mechanochemical coupling of two substeps in a single myosin V motor. Nat Struct Mol Biol 2004; 11:877-83. [PMID: 15286720 DOI: 10.1038/nsmb806] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 06/18/2004] [Indexed: 11/09/2022]
Abstract
Myosin V is a double-headed processive molecular motor that moves along an actin filament by taking 36-nm steps. Using optical trapping nanometry with high spatiotemporal resolution, we discovered that there are two possible pathways for the 36-nm steps, one with 12- and 24-nm substeps, in this order, and the other without substeps. Based on the analyses of effects of ATP, ADP and 2,3-butanedione 2-monoxime (a reagent shown here to slow ADP release from actomyosin V) on the dwell time and the occurrence frequency of the main and the intermediate states, we propose that the 12-nm substep occurs after ATP binding to the bound trailing head and the 24-nm substep results from a mechanical step following the isomerization of an actomyosin-ADP state on the bound leading head. When the isomerization precedes the 12-nm substep, the 36-nm step occurs without substeps.
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Affiliation(s)
- Sotaro Uemura
- Department of Physics, School of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
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121
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Abstract
Cytoplasmic transport is mediated by a group of molecular motors that typically work in isolation, under conditions where they must move their cargos long distances without dissociating from their tracks. This processive behavior requires specific adaptations of motor enzymology to meet these unique physiologic demands. One of these involves the ability of the two heads of a processive motor to communicate their structural states to each other. In this study, we examine a processive motor from the myosin superfamily myosin V. We have measured the kinetics of nucleotide release, of phosphate release, and of the weak-to-strong transition, as this motor interacts with actin, and we have used these studies to develop a model of how myosin V functions as a transport motor. Surprisingly, both heads release phosphate rapidly upon the initial encounter with an actin filament, suggesting that there is little or no intramolecular strain associated with this step. However, ADP release can be affected by both forward and rearward strain, and under steady-state conditions it is essentially prevented in the lead head until the rear head detaches. Many of these features are remarkably like those underlying the processive movement of kinesin on microtubules, supporting our hypothesis that different molecular motors satisfy the requirement for processive movement in similar ways, regardless of their particular family of origin.
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Affiliation(s)
- Steven S Rosenfeld
- Department of Neurology, University of Alabama, Birmingham, Alabama 35294, USA.
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122
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Klumpp LM, Brendza KM, Gatial JE, Hoenger A, Saxton WM, Gilbert SP. Microtubule-kinesin interface mutants reveal a site critical for communication. Biochemistry 2004; 43:2792-803. [PMID: 15005614 PMCID: PMC1543712 DOI: 10.1021/bi035830e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Strict coordination of the two motor domains of kinesin is required for driving the processive movement of organelles along microtubules. Glutamate 164 of the kinesin heavy chain was shown to be critical for kinesin function through in vivo genetics in Drosophila melanogaster. The mutant motor E164K exhibited reduced steady-state ATPase activity and higher affinity for both ATP and microtubules. Moreover, an alanine substitution at this position (E164A) caused similar defects. It became stalled on the microtubule and was unable to bind and hydrolyze ATP at the second motor domain. Glu(164), which has been conserved through evolution, is located at the motor-microtubule interface close to key residues on helix alpha12 of beta-tubulin. We explored further the contributions of Glu(164) to motor function using several site-directed mutant proteins: E164K, E164N, E164D, E164Q, and D165A. The results indicate that the microtubule-E164K complex can only bind and hydrolyze one ATP. ATP with increased salt was able to dissociate a population of E164K motors from the microtubule but could not dissociate E164A. We tested the basis of the stabilized microtubule interaction with E164K, E164N, and E164A. The results provide new insights about the motor-microtubule interface and the pathway of communication for processive motility.
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Affiliation(s)
- Lisa M Klumpp
- Department of Biological Sciences, 518 Langley Hall, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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123
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Cochran JC, Sontag CA, Maliga Z, Kapoor TM, Correia JJ, Gilbert SP. Mechanistic analysis of the mitotic kinesin Eg5. J Biol Chem 2004; 279:38861-70. [PMID: 15247293 PMCID: PMC1356567 DOI: 10.1074/jbc.m404203200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eg5 is a slow, plus-end-directed microtubule-based motor of the BimC kinesin family that is essential for bipolar spindle formation during eukaryotic cell division. We have analyzed two human Eg5/KSP motors, Eg5-367 and Eg5-437, and both are monomeric based on results from sedimentation velocity and sedimentation equilibrium centrifugation as well as analytical gel filtration. The steady-state parameters were: for Eg5-367: k(cat) = 5.5 s(-1), K(1/2,Mt) = 0.7 microm, and K(m,ATP) = 25 microm; and for Eg5-437: k(cat) = 2.9 s(-1), K(1/2,Mt) = 4.5 microm, and K(m,ATP) = 19 microm. 2'(3')-O-(N-Methylanthraniloyl)-ATP (mantATP) binding was rapid at 2-3 microm(-1)s(-1), followed immediately by ATP hydrolysis at 15 s(-1). ATP-dependent Mt.Eg5 dissociation was relatively slow and rate-limiting at 8 s(-1) with mantADP release at 40 s(-1). Surprisingly, Eg5-367 binds microtubules more effectively (11 microm(-1)s(-1)) than Eg5-437 (0.7 microm(-1)s(-1)), consistent with the steady-state K(1/2,Mt) and the mantADP release K(1/2,Mt). These results indicate that the ATPase pathway for monomeric Eg5 is more similar to conventional kinesin than the spindle motors Ncd and Kar3, where ADP product release is rate-limiting for steady-state turnover.
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Affiliation(s)
- Jared C. Cochran
- From the Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, the
| | - Christopher A. Sontag
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, the
| | - Zoltan Maliga
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, and the
| | - Tarun M. Kapoor
- Laboratory of Chemistry and Cell Biology, Rockefeller University, New York, New York 10021
| | - John J. Correia
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, the
| | - Susan P. Gilbert
- From the Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, the
- ** To whom correspondence should be addressed. Tel.: 412-624-5842; Fax: 412-624-4759; E-mail:
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124
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Sablin EP, Fletterick RJ. Coordination between Motor Domains in Processive Kinesins. J Biol Chem 2004; 279:15707-10. [PMID: 14973135 DOI: 10.1074/jbc.r300036200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Elena P Sablin
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, USA
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125
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Abstract
We have identified dimeric kinesin mutants that become stalled on the microtubule after one ATP turnover, unable to bind and hydrolyze ATP at their second site. We have used these mutants to determine the regulatory signal that allows ATP to bind to the forward head, such that processive movement can continue. The results show that phosphate release occurs from the rearward head before detachment, and detachment triggers active-site accessibility for ATP binding at the forward head. This mechanism, in which the rearward head controls the behavior of the forward head, may be conserved among processive motors.
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Affiliation(s)
- Lisa M Klumpp
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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126
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127
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Abstract
Kinesin is a processive motor that takes 8.3-nm center-of-mass steps along microtubules for each adenosine triphosphate hydrolyzed. Whether kinesin moves by a "hand-over-hand" or an "inchworm" model has been controversial. We have labeled a single head of the kinesin dimer with a Cy3 fluorophore and localized the position of the dye to within 2 nm before and after a step. We observed that single kinesin heads take steps of 17.3 +/- 3.3 nm. A kinetic analysis of the dwell times between steps shows that the 17-nm steps alternate with 0-nm steps. These results strongly support a hand-over-hand mechanism, and not an inchworm mechanism. In addition, our results suggest that kinesin is bound by both heads to the microtubule while it waits for adenosine triphosphate in between steps.
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Affiliation(s)
- Ahmet Yildiz
- Center for Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
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128
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Crevel IMTC, Nyitrai M, Alonso MC, Weiss S, Geeves MA, Cross RA. What kinesin does at roadblocks: the coordination mechanism for molecular walking. EMBO J 2003; 23:23-32. [PMID: 14685258 PMCID: PMC1271674 DOI: 10.1038/sj.emboj.7600042] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Accepted: 11/17/2003] [Indexed: 11/09/2022] Open
Abstract
Competing models for the coordination of processive stepping in kinesin can be tested by introducing a roadblock to prevent lead head attachment. We used T93N, an irreversibly binding mutant monomer, as a roadblock, and measured the rates of nucleotide-induced detachment of kinesin monomers or dimers with and without the T93N roadblock using microflash photolysis combined with stopped flow. Control nucleotide-induced monomer (rK340) unbinding was 73.6 s(-1) for ATP and 40.5 s(-1) for ADP. Control ADP-induced dimer (rK430) unbinding was 18.6 s(-1). Added 20 mM Pi slowed both monomer and dimer unbinding. With the roadblock in place, lead head attachment of dimers is prevented and ATP-induced trail head unbinding was then 42 s(-1). This is less than two-fold slower than the stepping rate of unimpeded rK430 dimers (50-70 s(-1)), indicating that during walking, lead head attachment induces at most only a slight (less than two-fold) acceleration of trail head detachment. As we discuss, this implies a coordination model having very fast (>2000 s(-1)) ATP-induced attachment of the lead head, followed by slower, strain-sensitive ADP release from the lead head.
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Affiliation(s)
- Isabelle M-TC Crevel
- Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey, UK
| | - Miklós Nyitrai
- Department of Biosciences, University of Kent, Canterbury, Kent, UK
- Research Group for Fluorescence Spectroscopy, Office for Academy Research Groups Attached to Universities and Other Institutions, Department of Biophysics, Faculty of Medicine, University of Pécs, Pécs, Hungary
| | - María C Alonso
- Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey, UK
| | - Stefan Weiss
- Department of Biosciences, University of Kent, Canterbury, Kent, UK
| | - Michael A Geeves
- Department of Biosciences, University of Kent, Canterbury, Kent, UK
| | - Robert A Cross
- Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey, UK
- Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted RH8 0TL, Surrey, UK. Tel.: +44 1883 722306; Fax: +44 1883 714 375; E-mail:
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129
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Abstract
Kinesin is a double-headed motor protein that moves along microtubules in 8-nanometer steps. Two broad classes of model have been invoked to explain kinesin movement: hand-over-hand and inchworm. In hand-over-hand models, the heads exchange leading and trailing roles with every step, whereas no such exchange is postulated for inchworm models, where one head always leads. By measuring the stepwise motion of individual enzymes, we find that some kinesin molecules exhibit a marked alternation in the dwell times between sequential steps, causing these motors to "limp" along the microtubule. Limping implies that kinesin molecules strictly alternate between two different conformations as they step, indicative of an asymmetric, hand-over-hand mechanism.
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Affiliation(s)
| | - Adrian N. Fehr
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Steven M. Block
- Department of Biological Sciences
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
- *To whom correspondence should be addressed. E-mail:
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