1
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Nishibe N, Maruta S. Photocontrol of small GTPase Ras fused with a photoresponsive protein. J Biochem 2024; 176:11-21. [PMID: 38366640 DOI: 10.1093/jb/mvae017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 01/08/2024] [Accepted: 01/31/2024] [Indexed: 02/18/2024] Open
Abstract
The small GTPase Ras plays an important role in intracellular signal transduction and functions as a molecular switch. In this study, we used a photoresponsive protein as the molecular regulatory device to photoregulate Ras GTPase activity. Photo zipper (PZ), a variant of the photoresponsive protein Aureochrome1 developed by Hisatomi et al. was incorporated into the C-terminus of Ras as a fusion protein. The three constructs of the Ras-PZ fusion protein had spacers of different lengths between Ras and PZ. They were designed using an Escherichia coli expression system. The Ras-PZ fusion proteins exhibited photoisomerization upon blue light irradiation and in the dark. Ras-PZ dimerized upon light irradiation. Moreover, Ras GTPase activity, which is accelerated by the Ras regulators guanine nucleotide exchange factors and GTPase-activating proteins, is controlled by photoisomerization. It has been suggested that light-responsive proteins are applicable to the photoswitching of the enzymatic activity of small GTPases as photoregulatory molecular devices.
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Affiliation(s)
- Nobuyuki Nishibe
- Department of Biosciences, Graduate School of Science and Engineering Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
| | - Shinsaku Maruta
- Department of Biosciences, Graduate School of Science and Engineering Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
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2
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Wang JM, Zhang FH, Liu ZX, Tang YJ, Li JF, Xie LP. Cancer on motors: How kinesins drive prostate cancer progression? Biochem Pharmacol 2024; 224:116229. [PMID: 38643904 DOI: 10.1016/j.bcp.2024.116229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/02/2024] [Accepted: 04/18/2024] [Indexed: 04/23/2024]
Abstract
Prostate cancer causes numerous male deaths annually. Although great progress has been made in the diagnosis and treatment of prostate cancer during the past several decades, much about this disease remains unknown, especially its pathobiology. The kinesin superfamily is a pivotal group of motor proteins, that contains a microtubule-based motor domain and features an adenosine triphosphatase activity and motility characteristics. Large-scale sequencing analyses based on clinical samples and animal models have shown that several members of the kinesin family are dysregulated in prostate cancer. Abnormal expression of kinesins could be linked to uncontrolled cell growth, inhibited apoptosis and increased metastasis ability. Additionally, kinesins may be implicated in chemotherapy resistance and escape immunologic cytotoxicity, which creates a barrier to cancer treatment. Here we cover the recent advances in understanding how kinesins may drive prostate cancer progression and how targeting their function may be a therapeutic strategy. A better understanding of kinesins in prostate cancer tumorigenesis may be pivotal for improving disease outcomes in prostate cancer patients.
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Affiliation(s)
- Jia-Ming Wang
- Department of Urology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Feng-Hao Zhang
- Department of Urology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Zi-Xiang Liu
- Department of Urology, The First Affiliated Hospital of Ningbo University, Ningbo, People's Republic of China
| | - Yi-Jie Tang
- Department of Urology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Jiang-Feng Li
- Department of Urology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China.
| | - Li-Ping Xie
- Department of Urology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People's Republic of China.
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3
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Zhang L, Piranej S, Namazi A, Narum S, Salaita K. "Turbo-Charged" DNA Motors with Optimized Sequence Enable Single-Molecule Nucleic Acid Sensing. Angew Chem Int Ed Engl 2024; 63:e202316851. [PMID: 38214887 PMCID: PMC10947818 DOI: 10.1002/anie.202316851] [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: 11/06/2023] [Revised: 12/22/2023] [Accepted: 01/10/2024] [Indexed: 01/13/2024]
Abstract
DNA motors that consume chemical energy to generate processive mechanical motion mimic natural motor proteins and have garnered interest due to their potential applications in dynamic nanotechnology, biosensing, and drug delivery. Such motors translocate by a catalytic cycle of binding, cleavage, and rebinding between DNA "legs" on the motor body and RNA "footholds" on a track. Herein, we address the well-documented trade-off between motor speed and processivity and investigate how these parameters are controlled by the affinity between DNA legs and their complementary footholds. Specifically, we explore the role of DNA leg length and GC content in tuning motor performance by dictating the rate of leg-foothold dissociation. Our investigations reveal that motors with 0 % GC content exhibit increased instantaneous velocities of up to 150 nm/sec, three-fold greater than previously reported DNA motors and comparable to the speeds of biological motor proteins. We also demonstrate that the faster speed and weaker forces generated by 0 % GC motors can be leveraged for enhanced capabilities in sensing. We observe single-molecule sensitivity when programming the motors to stall in response to the binding of nucleic acid targets. These findings offer insights for the design of high-performance DNA motors with promising real-world biosensing applications.
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Affiliation(s)
- Luona Zhang
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Selma Piranej
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Arshiya Namazi
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Steven Narum
- Wallace H. Coulter Department of Biomedical Engineering, Georgia, Institute of Technology and Emory University, Atlanta, GA 30322, USA
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia, Institute of Technology and Emory University, Atlanta, GA 30322, USA
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4
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Benoit MP, Hunter B, Allingham JS, Sosa H. New insights into the mechanochemical coupling mechanism of kinesin-microtubule complexes from their high-resolution structures. Biochem Soc Trans 2023; 51:1505-1520. [PMID: 37560910 PMCID: PMC10586761 DOI: 10.1042/bst20221238] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/28/2023] [Accepted: 08/01/2023] [Indexed: 08/11/2023]
Abstract
Kinesin motor proteins couple mechanical movements in their motor domain to the binding and hydrolysis of ATP in their nucleotide-binding pocket. Forces produced through this 'mechanochemical' coupling are typically used to mobilize kinesin-mediated transport of cargos along microtubules or microtubule cytoskeleton remodeling. This review discusses the recent high-resolution structures (<4 Å) of kinesins bound to microtubules or tubulin complexes that have resolved outstanding questions about the basis of mechanochemical coupling, and how family-specific modifications of the motor domain can enable its use for motility and/or microtubule depolymerization.
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Affiliation(s)
| | - Byron Hunter
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - John S. Allingham
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Hernando Sosa
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, U.S.A
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5
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Sladewski TE, Campbell PC, Billington N, D'Ordine A, Cole JL, de Graffenried CL. Cytokinesis in Trypanosoma brucei relies on an orphan kinesin that dynamically crosslinks microtubules. Curr Biol 2023; 33:899-911.e5. [PMID: 36787745 PMCID: PMC10023446 DOI: 10.1016/j.cub.2023.01.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 12/09/2022] [Accepted: 01/18/2023] [Indexed: 02/15/2023]
Abstract
Many single-celled eukaryotes have complex cell morphologies defined by microtubules arranged into higher-order structures. The auger-like shape of the parasitic protist Trypanosoma brucei (T. brucei) is mediated by a parallel array of microtubules that underlies the plasma membrane. The subpellicular array must be partitioned and segregated using a microtubule-based mechanism during cell division. We previously identified an orphan kinesin, KLIF, that localizes to the ingressing cleavage furrow and is essential for the completion of cytokinesis. We have characterized the biophysical properties of a truncated KLIF construct in vitro to gain mechanistic insight into the function of this novel kinesin. We find that KLIF is a non-processive dimeric kinesin that dynamically crosslinks microtubules. Microtubules crosslinked by KLIF in an antiparallel orientation are translocated relative to one another, while microtubules crosslinked parallel to one another remain static, resulting in the formation of organized parallel bundles. In addition, we find that KLIF stabilizes the alignment of microtubule plus ends. These features provide a mechanistic understanding for how KLIF functions to form a new pole of aligned microtubule plus ends that defines the shape of the new cell posterior, which is an essential requirement for the completion of cytokinesis in T. brucei.
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Affiliation(s)
- Thomas E Sladewski
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA; Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
| | - Paul C Campbell
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
| | - Neil Billington
- Laboratory of Physiology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda 20892, USA
| | - Alexandra D'Ordine
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - James L Cole
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
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6
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Vu HT, Zhang Z, Tehver R, Thirumalai D. Plus and minus ends of microtubules respond asymmetrically to kinesin binding by a long-range directionally driven allosteric mechanism. SCIENCE ADVANCES 2022; 8:eabn0856. [PMID: 35417226 PMCID: PMC9007332 DOI: 10.1126/sciadv.abn0856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
Although it is known that majority of kinesin motors walk predominantly toward the plus end of microtubules (MTs) in a hand-over-hand manner, the structural origin of the stepping directionality is not understood. To resolve this issue, we modeled the structures of kinesin-1 (Kin1), MT, and the Kin1-MT complex using the elastic network model and calculated the residue-dependent responses to a local perturbation in the constructs. Kin1 binding elicits an asymmetric response that is pronounced in α/β-tubulin dimers in the plus end of the MT. Kin1 opens the clefts of multiple plus end α/β-tubulin dimers, creating binding-competent conformations, which is required for processivity. Reciprocally, MT induces correlations between switches I and II in the motor and enhances fluctuations in adenosine 5'-diphosphate and the residues in the binding pocket. Our findings explain both the directionality of stepping and MT effects on a key step in the catalytic cycle of kinesin.
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Affiliation(s)
- Huong T. Vu
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Coventry CV4 7AL, UK
| | - Zhechun Zhang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Riina Tehver
- Department of Physics, Denison University, Granville, OH 43023, USA
| | - D. Thirumalai
- Department of Chemistry, University of Texas, Austin, TX 78702, USA
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7
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Debold EP. Mini‐ review: Recent insights into the relative timing of myosin’s powerstroke and release of phosphate. Cytoskeleton (Hoboken) 2022; 78:448-458. [DOI: 10.1002/cm.21695] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/25/2022] [Accepted: 03/08/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Edward P. Debold
- Department of Kinesiology University of Massachusetts Amherst Massachusetts
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8
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Pospich S, Sweeney HL, Houdusse A, Raunser S. High-resolution structures of the actomyosin-V complex in three nucleotide states provide insights into the force generation mechanism. eLife 2021; 10:e73724. [PMID: 34812732 PMCID: PMC8735999 DOI: 10.7554/elife.73724] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
The molecular motor myosin undergoes a series of major structural transitions during its force-producing motor cycle. The underlying mechanism and its coupling to ATP hydrolysis and actin binding are only partially understood, mostly due to sparse structural data on actin-bound states of myosin. Here, we report 26 high-resolution cryo-EM structures of the actomyosin-V complex in the strong-ADP, rigor, and a previously unseen post-rigor transition state that binds the ATP analog AppNHp. The structures reveal a high flexibility of myosin in each state and provide valuable insights into the structural transitions of myosin-V upon ADP release and binding of AppNHp, as well as the actomyosin interface. In addition, they show how myosin is able to specifically alter the structure of F-actin.
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Affiliation(s)
- Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - H Lee Sweeney
- Department of Pharmacology and Therapeutics and the Myology Institute, University of FloridaGainesvilleUnited States
| | - Anne Houdusse
- Structural Motility, Institut Curie, Centre National de la Recherche ScientifiqueParisFrance
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
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9
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Cook AD, Roberts AJ, Atherton J, Tewari R, Topf M, Moores CA. Cryo-EM structure of a microtubule-bound parasite kinesin motor and implications for its mechanism and inhibition. J Biol Chem 2021; 297:101063. [PMID: 34375637 PMCID: PMC8526983 DOI: 10.1016/j.jbc.2021.101063] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/23/2021] [Accepted: 08/05/2021] [Indexed: 11/25/2022] Open
Abstract
Plasmodium parasites cause malaria and are responsible annually for hundreds of thousands of deaths. Kinesins are a superfamily of microtubule-dependent ATPases that play important roles in the parasite replicative machinery, which is a potential target for antiparasite drugs. Kinesin-5, a molecular motor that cross-links microtubules, is an established antimitotic target in other disease contexts, but its mechanism in Plasmodium falciparum is unclear. Here, we characterized P. falciparum kinesin-5 (PfK5) using cryo-EM to determine the motor's nucleotide-dependent microtubule-bound structure and introduced 3D classification of individual motors into our microtubule image processing pipeline to maximize our structural insights. Despite sequence divergence in PfK5, the motor exhibits classical kinesin mechanochemistry, including ATP-induced subdomain rearrangement and cover neck bundle formation, consistent with its plus-ended directed motility. We also observed that an insertion in loop5 of the PfK5 motor domain creates a different environment in the well-characterized human kinesin-5 drug-binding site. Our data reveal the possibility for selective inhibition of PfK5 and can be used to inform future exploration of Plasmodium kinesins as antiparasite targets.
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Affiliation(s)
- Alexander D Cook
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Anthony J Roberts
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Joseph Atherton
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Rita Tewari
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom.
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10
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Scott B, Marang C, Woodward M, Debold EP. Myosin's powerstroke occurs prior to the release of phosphate from the active site. Cytoskeleton (Hoboken) 2021; 78:185-198. [PMID: 34331410 DOI: 10.1002/cm.21682] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 02/06/2023]
Abstract
Myosins are a family of motor proteins responsible for various forms of cellular motility, including muscle contraction and vesicular transport. The most fundamental aspect of myosin is its ability to transduce the chemical energy from the hydrolysis of ATP into mechanical work, in the form of force and/or motion. A key unanswered question of the transduction process is the timing of the force-generating powerstroke relative to the release of phosphate (Pi ) from the active site. We examined the ability of single-headed myosin Va to generate a powerstroke in a single molecule laser trap assay while maintaining Pi in its active site, by either elevating Pi in solution or by introducing a mutation in myosin's active site (S217A) to slow Pi -release from the active site. Upon binding to the actin filament, WT myosin generated a powerstoke rapidly (≥500 s-1 ) and without a detectable delay, both in the absence and presence of 30 mM Pi . The elevated levels of Pi did, however, affect event lifetime, eliminating the longest 25% of binding events, confirming that Pi rebound to myosin's active site and accelerated detachment. The S217A construct also generated a powerstroke similar in size and rate upon binding to actin despite the slower Pi release rate. These findings provide direct evidence that myosin Va generates a powerstroke with Pi still in its active site. Therefore, the findings are most consistent with a model in which the powerstroke occurs prior to the release of Pi from the active site.
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Affiliation(s)
- Brent Scott
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Christopher Marang
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Mike Woodward
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Edward P Debold
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, USA
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11
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Benoit MP, Asenjo AB, Paydar M, Dhakal S, Kwok BH, Sosa H. Structural basis of mechano-chemical coupling by the mitotic kinesin KIF14. Nat Commun 2021; 12:3637. [PMID: 34131133 PMCID: PMC8206134 DOI: 10.1038/s41467-021-23581-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 04/30/2021] [Indexed: 02/05/2023] Open
Abstract
KIF14 is a mitotic kinesin whose malfunction is associated with cerebral and renal developmental defects and several cancers. Like other kinesins, KIF14 couples ATP hydrolysis and microtubule binding to the generation of mechanical work, but the coupling mechanism between these processes is still not fully clear. Here we report 20 high-resolution (2.7-3.9 Å) cryo-electron microscopy KIF14-microtubule structures with complementary functional assays. Analysis procedures were implemented to separate coexisting conformations of microtubule-bound monomeric and dimeric KIF14 constructs. The data provide a comprehensive view of the microtubule and nucleotide induced KIF14 conformational changes. It shows that: 1) microtubule binding, the nucleotide species, and the neck-linker domain govern the transition between three major conformations of the motor domain; 2) an undocked neck-linker prevents the nucleotide-binding pocket to fully close and dampens ATP hydrolysis; 3) 13 neck-linker residues are required to assume a stable docked conformation; 4) the neck-linker position controls the hydrolysis rather than the nucleotide binding step; 5) the two motor domains of KIF14 dimers adopt distinct conformations when bound to the microtubule; and 6) the formation of the two-heads-bound-state introduces structural changes in both motor domains of KIF14 dimers. These observations provide the structural basis for a coordinated chemo-mechanical kinesin translocation model.
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Affiliation(s)
- Matthieu P.M.H. Benoit
- grid.251993.50000000121791997Department Physiology and Biophysics, Albert Einstein College of Medicine, New York, NY USA
| | - Ana B. Asenjo
- grid.251993.50000000121791997Department Physiology and Biophysics, Albert Einstein College of Medicine, New York, NY USA
| | - Mohammadjavad Paydar
- grid.14848.310000 0001 2292 3357Department of Medicine, Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, QC Canada
| | - Sabin Dhakal
- grid.14848.310000 0001 2292 3357Department of Medicine, Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, QC Canada
| | - Benjamin H. Kwok
- grid.14848.310000 0001 2292 3357Department of Medicine, Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, QC Canada
| | - Hernando Sosa
- grid.251993.50000000121791997Department Physiology and Biophysics, Albert Einstein College of Medicine, New York, NY USA
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12
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Mugnai ML, Thirumalai D. Step-Wise Hydration of Magnesium by Four Water Molecules Precedes Phosphate Release in a Myosin Motor. J Phys Chem B 2021; 125:1107-1117. [PMID: 33481593 DOI: 10.1021/acs.jpcb.0c10004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular motors, such as myosin, kinesin, and dynein, convert the energy released by the hydrolysis of ATP into mechanical work, thus allowing them to undergo directional motion on cytoskeletal tracks. A pivotal step in the chemomechanical transduction in myosin motors occurs after they bind to the actin filament, which triggers the release of phosphate (Pi, product of ATP hydrolysis) and the rotation of the lever arm. Here, we investigate the mechanism of phosphate release in myosin VI using extensive molecular dynamics simulations involving multiple trajectories of several μs. Because the escape of phosphate is expected to occur on time-scales on the order of milliseconds or more in myosin VI, we observed Pi release only if the trajectories were initiated with a rotated phosphate inside the nucleotide binding pocket. We discovered that although Pi populates the traditional "back door" route, phosphate exits through various other gateways, thus establishing the heterogeneity in the escape routes. Remarkably, we observed that the release of phosphate is preceded by a stepwise hydration of the ADP-bound magnesium ion. The release of the anion occurred only after four water molecules hydrated the cation (Mg2+). By performing comparative structural analyses, we show that hydration of magnesium is the key step in the phosphate release in a number of ATPases and GTPases. Nature may have evolved hydration of Mg2+ as a general molecular switch for Pi release, which is a universal step in the catalytic cycle of many machines that share little sequence or structural similarity.
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Affiliation(s)
- Mauro Lorenzo Mugnai
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - D Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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13
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Walker BC, Walczak CE, Cochran JC. Switch-1 instability at the active site decouples ATP hydrolysis from force generation in myosin II. Cytoskeleton (Hoboken) 2021; 78:3-13. [PMID: 33381891 PMCID: PMC7986744 DOI: 10.1002/cm.21650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 12/21/2020] [Accepted: 12/28/2020] [Indexed: 11/24/2022]
Abstract
Myosin active site elements (i.e., switch‐1) bind both ATP and a divalent metal to coordinate ATP hydrolysis. ATP hydrolysis at the active site is linked via allosteric communication to the actin polymer binding site and lever arm movement, thus coupling the free energy of ATP hydrolysis to force generation. How active site motifs are functionally linked to actin binding and the power stroke is still poorly understood. We hypothesize that destabilizing switch‐1 movement at the active site will negatively affect the tight coupling of the ATPase catalytic cycle to force production. Using a metal‐switch system, we tested the effect of interfering with switch‐1 coordination of the divalent metal cofactor on force generation. We found that while ATPase activity increased, motility was inhibited. Our results demonstrate that a single atom change that affects the switch‐1 interaction with the divalent metal directly affects actin binding and productive force generation. Even slight modification of the switch‐1 divalent metal coordination can decouple ATP hydrolysis from motility. Switch‐1 movement is therefore critical for both structural communication with the actin binding site, as well as coupling the energy of ATP hydrolysis to force generation.
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Affiliation(s)
- Benjamin C Walker
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
| | - Claire E Walczak
- Medical Sciences, Indiana University School of Medicine-Bloomington, Bloomington, Indiana, USA
| | - Jared C Cochran
- Department of Molecular & Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
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14
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How Kinesin-1 Utilize the Energy of Nucleotide: The Conformational Changes and Mechanochemical Coupling in the Unidirectional Motion of Kinesin-1. Int J Mol Sci 2020; 21:ijms21186977. [PMID: 32972035 PMCID: PMC7555842 DOI: 10.3390/ijms21186977] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/12/2020] [Accepted: 09/21/2020] [Indexed: 12/23/2022] Open
Abstract
Kinesin-1 is a typical motile molecular motor and the founding member of the kinesin family. The most significant feature in the unidirectional motion of kinesin-1 is its processivity. To realize the fast and processive movement on the microtubule lattice, kinesin-1 efficiently transforms the chemical energy of nucleotide binding and hydrolysis to the energy of mechanical movement. The chemical and mechanical cycle of kinesin-1 are coupled to avoid futile nucleotide hydrolysis. In this paper, the research on the mechanical pathway of energy transition and the regulating mechanism of the mechanochemical cycle of kinesin-1 is reviewed.
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15
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Elongation factor-Tu can repetitively engage aminoacyl-tRNA within the ribosome during the proofreading stage of tRNA selection. Proc Natl Acad Sci U S A 2020; 117:3610-3620. [PMID: 32024753 PMCID: PMC7035488 DOI: 10.1073/pnas.1904469117] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Elongation factor Tu (EF-Tu) facilitates rapid and accurate selection of aminoacyl-tRNA (aa-tRNA) by the bacterial ribosome during protein synthesis. We show that EF-Tu dissociates from the ribosome as aa-tRNA navigates the accommodation corridor en route to peptide bond formation. We find that EF-Tu’s release from the ribosome during aa-tRNA selection can be reversible. We also demonstrate that new ternary complex formation, accompanied by futile cycles of GTP hydrolysis, can occur on aa-tRNA bound within the ribosome. These findings inform on the decoding mechanism, the contributions of EF-Tu to the fidelity of translation, and the potential consequences of reduced rates of peptide bond formation on cellular physiology. The substrate for ribosomes actively engaged in protein synthesis is a ternary complex of elongation factor Tu (EF-Tu), aminoacyl-tRNA (aa-tRNA), and GTP. EF-Tu plays a critical role in mRNA decoding by increasing the rate and fidelity of aa-tRNA selection at each mRNA codon. Here, using three-color single-molecule fluorescence resonance energy transfer imaging and molecular dynamics simulations, we examine the timing and role of conformational events that mediate the release of aa-tRNA from EF-Tu and EF-Tu from the ribosome after GTP hydrolysis. Our investigations reveal that conformational changes in EF-Tu coordinate the rate-limiting passage of aa-tRNA through the accommodation corridor en route to the peptidyl transferase center of the large ribosomal subunit. Experiments using distinct inhibitors of the accommodation process further show that aa-tRNA must at least partially transit the accommodation corridor for EF-Tu⋅GDP to release. aa-tRNAs failing to undergo peptide bond formation at the end of accommodation corridor passage after EF-Tu release can be reengaged by EF-Tu⋅GTP from solution, coupled to GTP hydrolysis. These observations suggest that additional rounds of ternary complex formation can occur on the ribosome during proofreading, particularly when peptide bond formation is slow, which may serve to increase both the rate and fidelity of protein synthesis at the expense of GTP hydrolysis.
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Arata T. Myosin and Other Energy-Transducing ATPases: Structural Dynamics Studied by Electron Paramagnetic Resonance. Int J Mol Sci 2020; 21:E672. [PMID: 31968570 PMCID: PMC7014194 DOI: 10.3390/ijms21020672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/05/2020] [Accepted: 01/06/2020] [Indexed: 02/07/2023] Open
Abstract
The objective of this article was to document the energy-transducing and regulatory interactions in supramolecular complexes such as motor, pump, and clock ATPases. The dynamics and structural features were characterized by motion and distance measurements using spin-labeling electron paramagnetic resonance (EPR) spectroscopy. In particular, we focused on myosin ATPase with actin-troponin-tropomyosin, neural kinesin ATPase with microtubule, P-type ion-motive ATPase, and cyanobacterial clock ATPase. Finally, we have described the relationships or common principles among the molecular mechanisms of various energy-transducing systems and how the large-scale thermal structural transition of flexible elements from one state to the other precedes the subsequent irreversible chemical reactions.
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Affiliation(s)
- Toshiaki Arata
- Department of Biology, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan
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17
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Ma YL, Li T, Jin YM, Geng YZ, Ji Q. Shaft Function of Kinesin-1's α4 Helix in the Processive Movement. Cell Mol Bioeng 2019; 12:345-354. [PMID: 31719918 PMCID: PMC6816713 DOI: 10.1007/s12195-019-00581-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 06/17/2019] [Indexed: 10/26/2022] Open
Abstract
INTRODUCTION Kinesin-1 motor is a molecular walking machine constructed with amino acids. The understanding of how those structural elements play their mechanical roles is the key to the understanding of kinesin-1 mechanism. METHODS Using molecular dynamics simulations, we investigate the role of a helix structure, α4 (also called switch-II helix), of kinesin-1's motor domain in its processive movement along microtubule. RESULTS Through the analysis of the structure and the interactions between α4 and the surrounding residues in different nucleotide-binding states, we find that, mechanically, this helix functions as a shaft for kinesin-1's motor-domain rotation and, structurally, it is an amphipathic helix ensuring its shaft functioning. The hydrophobic side of α4 consists strictly of hydrophobic residues, making it behave like a lubricated surface in contact with the core β-sheet of kinesin-1's motor domain. The opposite hydrophilic side of α4 leans firmly against microtubule with charged residues locating at both ends to facilitate its positioning onto the intra-tubulin groove. CONCLUSIONS The special structural feature of α4 makes for an effective reduction of the conformational work in kinesin-1's force generation process.
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Affiliation(s)
- Yi-Long Ma
- Institute of Biophysics, Hebei University of Technology, Tianjin, 300401 China
- School of Science, Hebei University of Technology, Tianjin, 300401 China
| | - Tie Li
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, 300401 China
- School of Electrical Engineering, Hebei University of Technology, Tianjin, 300401 China
| | - Yu-Mei Jin
- Institute of Biophysics, Hebei University of Technology, Tianjin, 300401 China
- School of Science, Hebei University of Technology, Tianjin, 300401 China
| | - Yi-Zhao Geng
- Institute of Biophysics, Hebei University of Technology, Tianjin, 300401 China
- School of Science, Hebei University of Technology, Tianjin, 300401 China
| | - Qing Ji
- Institute of Biophysics, Hebei University of Technology, Tianjin, 300401 China
- School of Science, Hebei University of Technology, Tianjin, 300401 China
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18
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Li H, Yao XQ, Grant BJ. Comparative structural dynamic analysis of GTPases. PLoS Comput Biol 2018; 14:e1006364. [PMID: 30412578 PMCID: PMC6249014 DOI: 10.1371/journal.pcbi.1006364] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 11/21/2018] [Accepted: 10/11/2018] [Indexed: 12/30/2022] Open
Abstract
GTPases regulate a multitude of essential cellular processes ranging from movement and division to differentiation and neuronal activity. These ubiquitous enzymes operate by hydrolyzing GTP to GDP with associated conformational changes that modulate affinity for family-specific binding partners. There are three major GTPase superfamilies: Ras-like GTPases, heterotrimeric G proteins and protein-synthesizing GTPases. Although they contain similar nucleotide-binding sites, the detailed mechanisms by which these structurally and functionally diverse superfamilies operate remain unclear. Here we compare and contrast the structural dynamic mechanisms of each superfamily using extensive molecular dynamics (MD) simulations and subsequent network analysis approaches. In particular, dissection of the cross-correlations of atomic displacements in both the GTP and GDP-bound states of Ras, transducin and elongation factor EF-Tu reveals analogous dynamic features. This includes similar dynamic communities and subdomain structures (termed lobes). For all three proteins the GTP-bound state has stronger couplings between equivalent lobes. Network analysis further identifies common and family-specific residues mediating the state-specific coupling of distal functional sites. Mutational simulations demonstrate how disrupting these couplings leads to distal dynamic effects at the nucleotide-binding site of each family. Collectively our studies extend current understanding of GTPase allosteric mechanisms and highlight previously unappreciated similarities across functionally diverse families. GTPases are a large superfamily of essential enzymes that regulate a variety of cellular processes. They share a common core structure supporting nucleotide binding and hydrolysis, and are potentially descended from the same ancestor. Yet their biological functions diverge dramatically, ranging from cell division and movement to signal transduction and translation. It has been shown that conformational changes through binding to different substrates underlie the regulation of their activities. Here we investigate the conformational dynamics of three typical GTPases by in silico simulation. We find that these three GTPases possess overall similar substrate-associated dynamic features, beyond their distinct functions. Further identification of key common and family-specific elements in these three families helps us understand how enzymes are adapted to acquire distinct functions from a common core structure. Our results provide unprecedented insights into the functional mechanism of GTPases in general, which potentially facilitates novel protein design in the future.
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Affiliation(s)
- Hongyang Li
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, United States of America
| | - Xin-Qiu Yao
- Department of Chemistry, Georgia State University, Atlanta, GA, United States of America
| | - Barry J. Grant
- Division of Biological Sciences, Section of Molecular Biology, University of California, San Diego, La Jolla, CA, United States of America
- * E-mail:
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19
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Molecular switch-like regulation enables global subunit coordination in a viral ring ATPase. Proc Natl Acad Sci U S A 2018; 115:7961-7966. [PMID: 30012596 DOI: 10.1073/pnas.1802736115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Subunits in multimeric ring-shaped motors must coordinate their activities to ensure correct and efficient performance of their mechanical tasks. Here, we study WT and arginine finger mutants of the pentameric bacteriophage φ29 DNA packaging motor. Our results reveal the molecular interactions necessary for the coordination of ADP-ATP exchange and ATP hydrolysis of the motor's biphasic mechanochemical cycle. We show that two distinct regulatory mechanisms determine this coordination. In the first mechanism, the DNA up-regulates a single subunit's catalytic activity, transforming it into a global regulator that initiates the nucleotide exchange phase and the hydrolysis phase. In the second, an arginine finger in each subunit promotes ADP-ATP exchange and ATP hydrolysis of its neighbor. Accordingly, we suggest that the subunits perform the roles described for GDP exchange factors and GTPase-activating proteins observed in small GTPases. We propose that these mechanisms are fundamental to intersubunit coordination and are likely present in other ring ATPases.
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20
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Nebenführ A, Dixit R. Kinesins and Myosins: Molecular Motors that Coordinate Cellular Functions in Plants. ANNUAL REVIEW OF PLANT BIOLOGY 2018; 69:329-361. [PMID: 29489391 PMCID: PMC6653565 DOI: 10.1146/annurev-arplant-042817-040024] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Kinesins and myosins are motor proteins that can move actively along microtubules and actin filaments, respectively. Plants have evolved a unique set of motors that function as regulators and organizers of the cytoskeleton and as drivers of long-distance transport of various cellular components. Recent progress has established the full complement of motors encoded in plant genomes and has revealed valuable insights into the cellular functions of many kinesin and myosin isoforms. Interestingly, several of the motors were found to functionally connect the two cytoskeletal systems and thereby to coordinate their activities. In this review, we discuss the available genetic, cell biological, and biochemical data for each of the plant kinesin and myosin families from the context of their subcellular mechanism of action as well as their physiological function in the whole plant. We particularly emphasize work that illustrates mechanisms by which kinesins and myosins coordinate the activities of the cytoskeletal system.
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Affiliation(s)
- Andreas Nebenführ
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996-0840, USA;
| | - Ram Dixit
- Department of Biology and Center for Engineering Mechanobiology, Washington University, St. Louis, Missouri 63130-4899, USA;
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21
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Benoit MPMH, Asenjo AB, Sosa H. Cryo-EM reveals the structural basis of microtubule depolymerization by kinesin-13s. Nat Commun 2018; 9:1662. [PMID: 29695795 PMCID: PMC5916938 DOI: 10.1038/s41467-018-04044-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/27/2018] [Indexed: 11/25/2022] Open
Abstract
Kinesin-13s constitute a distinct group within the kinesin superfamily of motor proteins that promote microtubule depolymerization and lack motile activity. The molecular mechanism by which kinesin-13s depolymerize microtubules and are adapted to perform a seemingly very different activity from other kinesins is still unclear. To address this issue, here we report the near atomic resolution cryo-electron microscopy (cryo-EM) structures of Drosophila melanogaster kinesin-13 KLP10A protein constructs bound to curved or straight tubulin in different nucleotide states. These structures show how nucleotide induced conformational changes near the catalytic site are coupled with movement of the kinesin-13-specific loop-2 to induce tubulin curvature leading to microtubule depolymerization. The data highlight a modular structure that allows similar kinesin core motor-domains to be used for different functions, such as motility or microtubule depolymerization. Kinesin-13s are microtubule depolymerases that lack motile activity. Here the authors present the cryo-EM structures of kinesin-13 microtubule complexes in different nucleotide bound states, which reveal how ATP hydrolysis is linked to conformational changes and propose a model for kinesin induced depolymerisation.
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Affiliation(s)
- Matthieu P M H Benoit
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ana B Asenjo
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Hernando Sosa
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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22
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Kiani FA, Fischer S. Comparing the catalytic strategy of ATP hydrolysis in biomolecular motors. Phys Chem Chem Phys 2018; 18:20219-33. [PMID: 27296627 DOI: 10.1039/c6cp01364c] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
ATP-driven biomolecular motors utilize the chemical energy obtained from the ATP hydrolysis to perform vital tasks in living cells. Understanding the mechanism of enzyme-catalyzed ATP hydrolysis reaction has substantially progressed lately thanks to combined quantum/classical molecular mechanics (QM/MM) simulations. Here, we present a comparative summary of the most recent QM/MM results for myosin, kinesin and F1-ATPase motors. These completely different motors achieve the acceleration of ATP hydrolysis through a very similar catalytic mechanism. ATP hydrolysis has high activation energy because it involves the breaking of two strong bonds, namely the Pγ-Oβγ bond of ATP and the H-O bond of lytic water. The key to the four-fold decrease in the activation barrier by the three enzymes is that the breaking of the Pγ-Oβγ bond precedes the deprotonation of the lytic water molecule, generating a metaphosphate hydrate complex. The resulting singly charged trigonal planar PγO3(-) metaphosphate is a better electrophilic target for attack by an OaH(-) hydroxyl group. The formation of this OaH(-) is promoted by a strong polarization of the lytic water: in all three proteins, this water is forming a hydrogen-bond with a backbone carbonyl group and interacts with the carboxylate group of glutamate (either directly or via an intercalated water molecule). This favors the shedding of one proton by the attacking water. The abstracted proton is transferred to the γ-phosphate via various proton wires, resulting in a H2PγO4(-)/ADP(3-) product state. This catalytic strategy is so effective that most other nucleotide hydrolyzing enzymes adopt a similar approach, as suggested by their very similar triphosphate binding sites.
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Affiliation(s)
- Farooq Ahmad Kiani
- Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Im Neuenheimer Feld 205, D-69120 Heidelberg, Germany. and Research Center for Modeling and Simulation (RCMS), National University of Sciences and Technology (NUST), Sector H-12, 44000, Islamabad, Pakistan.
| | - Stefan Fischer
- Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Im Neuenheimer Feld 205, D-69120 Heidelberg, Germany.
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23
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Hwang W, Lang MJ, Karplus M. Kinesin motility is driven by subdomain dynamics. eLife 2017; 6:28948. [PMID: 29111975 PMCID: PMC5718755 DOI: 10.7554/elife.28948] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 11/03/2017] [Indexed: 12/13/2022] Open
Abstract
The microtubule (MT)-associated motor protein kinesin utilizes its conserved ATPase head to achieve diverse motility characteristics. Despite considerable knowledge about how its ATPase activity and MT binding are coupled to the motility cycle, the atomic mechanism of the core events remain to be found. To obtain insights into the mechanism, we performed 38.5 microseconds of all-atom molecular dynamics simulations of kinesin-MT complexes in different nucleotide states. Local subdomain dynamics were found to be essential for nucleotide processing. Catalytic water molecules are dynamically organized by the switch domains of the nucleotide binding pocket while ATP is torsionally strained. Hydrolysis products are 'pulled' by switch-I, and a new ATP is 'captured' by a concerted motion of the α0/L5/switch-I trio. The dynamic and wet kinesin-MT interface is tuned for rapid interactions while maintaining specificity. The proposed mechanism provides the flexibility necessary for walking in the crowded cellular environment. Motor proteins called kinesins perform a number of different roles inside cells, including transporting cargo and organizing filaments called microtubules to generate the force needed for a cell to divide. Kinesins move along the microtubules, with different kinesins moving in different ways: some ‘walk’, some jump, and some destroy the microtubule as they travel along it. All kinesins power their movements using the same molecule as fuel – adenosine triphosphate, known as ATP for short. Energy stored in ATP is released by a chemical reaction known as hydrolysis, which uses water to break off specific parts of the ATP molecule. The site to which ATP binds in a kinesin has a similar structure to the ATP binding site of many other proteins that use ATP. However, little was known about the way in which kinesin uses ATP as a fuel, including how ATP binds to kinesin and is hydrolyzed, and how the products of hydrolysis are released. These events are used to power the motor protein. Hwang et al. have used powerful computer simulation methods to examine in detail how ATP interacts with kinesin whilst moving across a microtubule. The simulations suggest that regions (or 'domains') of kinesin near the ATP binding site move around to help in processing ATP. These kinesin domains trap a nearby ATP molecule from the environment and help to deliver water molecules to ATP for hydrolysis. Hwang et al. also found that the domain motion subsequently helps in the release of the hydrolysis products by kinesin. The domains around the ATP pocket vary among the kinesins and these differences may enable kinesins to fine-tune how they use ATP to move. Further investigations will help us understand why different kinesin families behave differently. They will also contribute to exploring how kinesin inhibitors might be used as anti-cancer drugs.
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Affiliation(s)
- Wonmuk Hwang
- Department of Biomedical Engineering, Texas A&M University, College Station, United States.,Department of Materials Science & Engineering, Texas A&M University, College Station, United States.,School of Computational Sciences, Korea Institute for Advanced Study, Seoul, Korea
| | - Matthew J Lang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, United States.,Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, United States
| | - Martin Karplus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, United States.,Laboratoire de Chimie Biophysique, ISIS, Université de Strasbourg, Strasbourg, France
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24
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Jennings S, Chenevert M, Liu L, Mottamal M, Wojcik EJ, Huckaba TM. Characterization of kinesin switch I mutations that cause hereditary spastic paraplegia. PLoS One 2017; 12:e0180353. [PMID: 28678816 PMCID: PMC5498027 DOI: 10.1371/journal.pone.0180353] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/14/2017] [Indexed: 11/18/2022] Open
Abstract
Kif5A is a neuronally-enriched isoform of the Kinesin-1 family of cellular transport motors. 23 separate mutations in the motor domain of Kif5A have been identified in patients with the complicated form of hereditary spastic paraplegia (HSP). We performed in vitro assays on dimeric recombinant Kif5A with HSP-causing mutations in the Switch I domain, which participates in the coordination and hydrolysis of ATP by kinesin. We observed a variety of significantly reduced catalytic and mechanical activities as a result of each mutation, with the shared phenotype from each that motility was significantly reduced. Substitution of Mn2+ for Mg2+ in our reaction buffers provides a dose-dependent rescue in both the catalytic and ensemble mechanical properties of the S203C mutant. This work provides mechanistic insight into the cause of HSP in patients with these mutations and points to future experiments to further dissect the root cause of this disease.
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Affiliation(s)
- Scott Jennings
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Madeline Chenevert
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Liqiong Liu
- Department of Biochemistry and Molecular Biology, LSU School of Medicine & Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Madhusoodanan Mottamal
- RCMI Molecular Modeling Core, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Edward J. Wojcik
- Department of Biochemistry and Molecular Biology, LSU School of Medicine & Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Thomas M. Huckaba
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
- * E-mail:
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25
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Functional implication of the common evolutionary origin of nuclear pore complex and endomembrane management systems. Semin Cell Dev Biol 2017; 68:10-17. [PMID: 28473267 DOI: 10.1016/j.semcdb.2017.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 04/26/2017] [Indexed: 11/24/2022]
Abstract
Nuclear pore complexes (NPCs) are the sole gateway between the cytoplasm and the nucleus serving both as stringent permeability barrier and active transporters between the two compartments of eukaryotic cells. Complete mechanistic understanding of how these two functions are implemented within one and the same transport machine has not been attained to date. Based on several lines of structural evidence, a hypothesis was proposed postulating that NPCs shares common evolutionary origin with other intracellular systems responsible for active management of endomembranes. In this review we attempt to summarize the evidence supporting this hypothesis. The structural data obtained so far is evaluated and supplemented with the analysis of the functional evidence. Based on this analysis, a model is proposed which integrates the knowledge from the field of NPC function with that obtained from other endomembrane management systems in an attempt to shed new light on the mechanism of the NPC active transport.
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26
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Cross RA. Review: Mechanochemistry of the kinesin-1 ATPase. Biopolymers 2017; 105:476-82. [PMID: 27120111 PMCID: PMC4924600 DOI: 10.1002/bip.22862] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 04/12/2016] [Accepted: 04/17/2016] [Indexed: 01/01/2023]
Abstract
Kinesins are P‐loop NTPases that can do mechanical work. Like small G‐proteins, to which they are related, kinesins execute a program of active site conformational changes that cleaves the terminal phosphate from an NTP substrate. But unlike small G‐proteins, kinesins can amplify and harness these conformational changes in order to exert force. In this short review I summarize current ideas about how the kinesin active site works and outline how the active site chemistry is coupled to the larger‐scale structural cycle of the kinesin motor domain. Focusing largely on kinesin‐1, the best‐studied kinesin, I discuss how the active site switch machinery of kinesin cycles between three distinct states, how docking of the neck linker stabilizes two of these states, and how tension‐sensitive and position‐sensitive neck linker docking may modulate both the hydrolysis step of ATP turnover and the trapping of product ADP in the active site. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 476–482, 2016.
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Affiliation(s)
- R A Cross
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Coventry, CV4 7AL, UK
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27
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Richard J, Kim ED, Nguyen H, Kim CD, Kim S. Allostery Wiring Map for Kinesin Energy Transduction and Its Evolution. J Biol Chem 2016; 291:20932-20945. [PMID: 27507814 PMCID: PMC5076506 DOI: 10.1074/jbc.m116.733675] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Indexed: 12/28/2022] Open
Abstract
How signals between the kinesin active and cytoskeletal binding sites are transmitted is an open question and an allosteric question. By extracting correlated evolutionary changes within 700+ sequences, we built a model of residues that are energetically coupled and that define molecular routes for signal transmission. Typically, these coupled residues are located at multiple distal sites and thus are predicted to form a complex, non-linear network that wires together different functional sites in the protein. Of note, our model connected the site for ATP hydrolysis with sites that ultimately utilize its free energy, such as the microtubule-binding site, drug-binding loop 5, and necklinker. To confirm the calculated energetic connectivity between non-adjacent residues, double-mutant cycle analysis was conducted with 22 kinesin mutants. There was a direct correlation between thermodynamic coupling in experiment and evolutionarily derived energetic coupling. We conclude that energy transduction is coordinated by multiple distal sites in the protein rather than only being relayed through adjacent residues. Moreover, this allosteric map forecasts how energetic orchestration gives rise to different nanomotor behaviors within the superfamily.
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Affiliation(s)
- Jessica Richard
- From the Department of Biochemistry and Molecular Biology, Louisiana State University School of Medicine & Health Sciences Center, New Orleans, Louisiana 70112
| | - Elizabeth D Kim
- From the Department of Biochemistry and Molecular Biology, Louisiana State University School of Medicine & Health Sciences Center, New Orleans, Louisiana 70112
| | - Hoang Nguyen
- From the Department of Biochemistry and Molecular Biology, Louisiana State University School of Medicine & Health Sciences Center, New Orleans, Louisiana 70112
| | - Catherine D Kim
- From the Department of Biochemistry and Molecular Biology, Louisiana State University School of Medicine & Health Sciences Center, New Orleans, Louisiana 70112
| | - Sunyoung Kim
- From the Department of Biochemistry and Molecular Biology, Louisiana State University School of Medicine & Health Sciences Center, New Orleans, Louisiana 70112
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28
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Wang D, Zhu L, Liao M, Zeng T, Zhuo W, Yang S, Wu W. MYO6 knockdown inhibits the growth and induces the apoptosis of prostate cancer cells by decreasing the phosphorylation of ERK1/2 and PRAS40. Oncol Rep 2016; 36:1285-92. [PMID: 27431378 DOI: 10.3892/or.2016.4910] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 01/08/2016] [Indexed: 11/05/2022] Open
Abstract
Prostate cancer is the second most frequently diagnosed cancer among males around the world. Myosin VI (MYO6), as a motor protein, has been reported to be implicated in cancer-related cell migration and cellular functions. To investigate the role of MYO6 in prostate cancer, immunohistochemical analysis was firstly applied to prostate cancer tissues and revealed that MYO6 was closely related with the Gleason score in prostate cancer. Then we used specific short hairpin RNA (shRNA) to downregulate MYO6 expression in DU145 and PC-3 cells and found that decreased MYO6 expression significantly suppressed cell proliferation, as determined by MTT and colony formation assays. Flow cytometry confirmed that the suppression of MYO6 promoted cell cycle arrest at the G2/M and sub-G1 phase in the DU145 cells. Furthermore, PathScan intracellular signaling array analysis demonstrated that the phosphorylation of ERK1/2 and PRAS40 was downregulated in the DU145 cells following MYO6 knockdown. Knockdown of MYO6 downregulated the expression of AKT3 and upregulated the expression of PARP, as confirmed by western blot analysis. These results suggest that MYO6 plays an essential role in the progression of prostate cancer and silencing of MYO6 may be a promising therapeutic approach for prostate cancer.
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Affiliation(s)
- Dong Wang
- Department of Urology, Fuzhou Dongfang Hospital, Xiamen University, Xiamen 361005, P.R. China
| | - Libing Zhu
- Department of Urology, Lushan Sanatorium of the PLA, Lushan 332000, P.R. China
| | - Min Liao
- Department of Urology, Fuzhou General Hospital, Fujian Medical University, Fuzhou, Fujian 350025, P.R. China
| | - Tengyue Zeng
- Department of Urology, Fuzhou General Hospital, Fujian Medical University, Fuzhou, Fujian 350025, P.R. China
| | - Wenli Zhuo
- Department of Urology, Fuzhou General Hospital, Fujian Medical University, Fuzhou, Fujian 350025, P.R. China
| | - Shunliang Yang
- Department of Urology, Fuzhou General Hospital, Fujian Medical University, Fuzhou, Fujian 350025, P.R. China
| | - Weizhen Wu
- Department of Urology, Fuzhou Dongfang Hospital, Xiamen University, Xiamen 361005, P.R. China
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Biological Nanomotors with a Revolution, Linear, or Rotation Motion Mechanism. Microbiol Mol Biol Rev 2016; 80:161-86. [PMID: 26819321 DOI: 10.1128/mmbr.00056-15] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The ubiquitous biological nanomotors were classified into two categories in the past: linear and rotation motors. In 2013, a third type of biomotor, revolution without rotation (http://rnanano.osu.edu/movie.html), was discovered and found to be widespread among bacteria, eukaryotic viruses, and double-stranded DNA (dsDNA) bacteriophages. This review focuses on recent findings about various aspects of motors, including chirality, stoichiometry, channel size, entropy, conformational change, and energy usage rate, in a variety of well-studied motors, including FoF1 ATPase, helicases, viral dsDNA-packaging motors, bacterial chromosome translocases, myosin, kinesin, and dynein. In particular, dsDNA translocases are used to illustrate how these features relate to the motion mechanism and how nature elegantly evolved a revolution mechanism to avoid coiling and tangling during lengthy dsDNA genome transportation in cell division. Motor chirality and channel size are two factors that distinguish rotation motors from revolution motors. Rotation motors use right-handed channels to drive the right-handed dsDNA, similar to the way a nut drives the bolt with threads in same orientation; revolution motors use left-handed motor channels to revolve the right-handed dsDNA. Rotation motors use small channels (<2 nm in diameter) for the close contact of the channel wall with single-stranded DNA (ssDNA) or the 2-nm dsDNA bolt; revolution motors use larger channels (>3 nm) with room for the bolt to revolve. Binding and hydrolysis of ATP are linked to different conformational entropy changes in the motor that lead to altered affinity for the substrate and allow work to be done, for example, helicase unwinding of DNA or translocase directional movement of DNA.
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Abstract
Vascular smooth muscle (VSM; see Table 1 for a list of abbreviations) is a heterogeneous biomaterial comprised of cells and extracellular matrix. By surrounding tubes of endothelial cells, VSM forms a regulated network, the vasculature, through which oxygenated blood supplies specialized organs, permitting the development of large multicellular organisms. VSM cells, the engine of the vasculature, house a set of regulated nanomotors that permit rapid stress-development, sustained stress-maintenance and vessel constriction. Viscoelastic materials within, surrounding and attached to VSM cells, comprised largely of polymeric proteins with complex mechanical characteristics, assist the engine with countering loads imposed by the heart pump, and with control of relengthening after constriction. The complexity of this smart material can be reduced by classical mechanical studies combined with circuit modeling using spring and dashpot elements. Evaluation of the mechanical characteristics of VSM requires a more complete understanding of the mechanics and regulation of its biochemical parts, and ultimately, an understanding of how these parts work together to form the machinery of the vascular tree. Current molecular studies provide detailed mechanical data about single polymeric molecules, revealing viscoelasticity and plasticity at the protein domain level, the unique biological slip-catch bond, and a regulated two-step actomyosin power stroke. At the tissue level, new insight into acutely dynamic stress-strain behavior reveals smooth muscle to exhibit adaptive plasticity. At its core, physiology aims to describe the complex interactions of molecular systems, clarifying structure-function relationships and regulation of biological machines. The intent of this review is to provide a comprehensive presentation of one biomachine, VSM.
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Affiliation(s)
- Paul H Ratz
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA
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31
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Esmaeeli Nieh S, Madou MRZ, Sirajuddin M, Fregeau B, McKnight D, Lexa K, Strober J, Spaeth C, Hallinan BE, Smaoui N, Pappas JG, Burrow TA, McDonald MT, Latibashvili M, Leshinsky-Silver E, Lev D, Blumkin L, Vale RD, Barkovich AJ, Sherr EH. De novo mutations in KIF1A cause progressive encephalopathy and brain atrophy. Ann Clin Transl Neurol 2015; 2:623-35. [PMID: 26125038 PMCID: PMC4479523 DOI: 10.1002/acn3.198] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 03/04/2015] [Indexed: 12/30/2022] Open
Abstract
Objective To determine the cause and course of a novel syndrome with progressive encephalopathy and brain atrophy in children. Methods Clinical whole-exome sequencing was performed for global developmental delay and intellectual disability; some patients also had spastic paraparesis and evidence of clinical regression. Six patients were identified with de novo missense mutations in the kinesin gene KIF1A. The predicted functional disruption of these mutations was assessed in silico to compare the calculated conformational flexibility and estimated efficiency of ATP binding to kinesin motor domains of wild-type (WT) versus mutant alleles. Additionally, an in vitro microtubule gliding assay was performed to assess the effects of de novo dominant, inherited recessive, and polymorphic variants on KIF1A motor function. Results All six subjects had severe developmental delay, hypotonia, and varying degrees of hyperreflexia and spastic paraparesis. Microcephaly, cortical visual impairment, optic neuropathy, peripheral neuropathy, ataxia, epilepsy, and movement disorders were also observed. All six patients had a degenerative neurologic course with progressive cerebral and cerebellar atrophy seen on sequential magnetic resonance imaging scans. Computational modeling of mutant protein structures when compared to WT kinesin showed substantial differences in conformational flexibility and ATP-binding efficiency. The de novo KIF1A mutants were nonmotile in the microtubule gliding assay. Interpretation De novo mutations in KIF1A cause a degenerative neurologic syndrome with brain atrophy. Computational and in vitro assays differentiate the severity of dominant de novo heterozygous versus inherited recessive KIF1A mutations. The profound effect de novo mutations have on axonal transport is likely related to the cause of progressive neurologic impairment in these patients.
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Affiliation(s)
- Sahar Esmaeeli Nieh
- Department of Neurology, University of California San Francisco, California, 94158
| | - Maura R Z Madou
- Department of Neurology, University of California San Francisco, California, 94158
| | - Minhajuddin Sirajuddin
- Department of Cellular and Molecular Pharmacology and the Howard Hughes Medical Institute, University of California San Francisco, California ; Cardiovascular Biology and Diseases, Institute of Stem Cell Biology and Regenerative Medicine, NCBS-TIFR Bangalore, India
| | - Brieana Fregeau
- Department of Neurology, University of California San Francisco, California, 94158
| | | | - Katrina Lexa
- Department of Pharmaceutical Chemistry, University of California San Francisco San Francisco, California
| | - Jonathan Strober
- Department of Neurology, University of California San Francisco, California, 94158
| | - Christine Spaeth
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio
| | - Barbara E Hallinan
- Division of Neurology, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio
| | | | - John G Pappas
- Department of Pediatrics, Clinical Genetic Services, NYU School of Medicine New York, New York
| | - Thomas A Burrow
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio ; Department of pediatrics, University of Cincinnati School of Medicine Cincinnati, Ohio
| | - Marie T McDonald
- Section of Medical Genetics, Department of Pediatrics, Duke University Durham, North Carolina
| | - Mariam Latibashvili
- Department of Neurology, University of California San Francisco, California, 94158 ; University of California San Diego, California
| | - Esther Leshinsky-Silver
- Molecular Genetics Laboratory, and Metabolic-Neurogenetic Service, Wolfson Medical Center and Sackler Medical School, Tel Aviv University Tel Aviv, Israel
| | - Dorit Lev
- Institute of Medical Genetics and Metabolic Neurogenetic Service, Wolfson Medical Center and Sackler Medical School, Tel Aviv University Tel Aviv, Israel
| | - Luba Blumkin
- Pediatric Neurology Unit and Metabolic Neurogenetic Service, Wolfson Medical Center, Holon and Sackler Medical School, Tel Aviv University Tel Aviv, Israel
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology and the Howard Hughes Medical Institute, University of California San Francisco, California
| | - Anthony James Barkovich
- Department of Radiology and Biomedical Imaging, University of California San Francisco, California
| | - Elliott H Sherr
- Department of Neurology, University of California San Francisco, California, 94158
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32
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Esque J, Cecchini M. Accurate Calculation of Conformational Free Energy Differences in Explicit Water: The Confinement–Solvation Free Energy Approach. J Phys Chem B 2015; 119:5194-207. [DOI: 10.1021/acs.jpcb.5b01632] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Jeremy Esque
- Laboratoire d’Ingénierie
des Fonctions Moléculaires (ISIS), UMR 7006 CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
| | - Marco Cecchini
- Laboratoire d’Ingénierie
des Fonctions Moléculaires (ISIS), UMR 7006 CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
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Nagy GN, Marton L, Contet A, Ozohanics O, Ardelean LM, Révész Á, Vékey K, Irimie FD, Vial H, Cerdan R, Vértessy BG. Composite Aromatic Boxes for Enzymatic Transformations of Quaternary Ammonium Substrates. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Salsi E, Farah E, Netter Z, Dann J, Ermolenko DN. Movement of elongation factor G between compact and extended conformations. J Mol Biol 2014; 427:454-67. [PMID: 25463439 DOI: 10.1016/j.jmb.2014.11.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/28/2014] [Accepted: 11/10/2014] [Indexed: 11/19/2022]
Abstract
Previous structural studies suggested that ribosomal translocation is accompanied by large interdomain rearrangements of elongation factor G (EF-G). Here, we follow the movement of domain IV of EF-G relative to domain II of EF-G using ensemble and single-molecule Förster resonance energy transfer. Our results indicate that ribosome-free EF-G predominantly adopts a compact conformation that can also, albeit infrequently, transition into a more extended conformation in which domain IV moves away from domain II. By contrast, ribosome-bound EF-G predominantly adopts an extended conformation regardless of whether it is interacting with pretranslocation ribosomes or with posttranslocation ribosomes. Our data suggest that ribosome-bound EF-G may also occasionally sample at least one more compact conformation. GTP hydrolysis catalyzed by EF-G does not affect the relative stability of the observed conformations in ribosome-free and ribosome-bound EF-G. Our data support a model suggesting that, upon binding to a pretranslocation ribosome, EF-G moves from a compact to a more extended conformation. This transition is not coupled to but likely precedes both GTP hydrolysis and mRNA/tRNA translocation.
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Affiliation(s)
- Enea Salsi
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Elie Farah
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Zoe Netter
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Jillian Dann
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Dmitri N Ermolenko
- Department of Biochemistry and Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA.
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35
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Nagy GN, Marton L, Contet A, Ozohanics O, Ardelean LM, Révész A, Vékey K, Irimie FD, Vial H, Cerdan R, Vértessy BG. Composite aromatic boxes for enzymatic transformations of quaternary ammonium substrates. Angew Chem Int Ed Engl 2014; 53:13471-6. [PMID: 25283789 DOI: 10.1002/anie.201408246] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Indexed: 11/07/2022]
Abstract
Cation-π interactions to cognate ligands in enzymes have key roles in ligand binding and enzymatic catalysis. We have deciphered the key functional role of both charged and aromatic residues within the choline binding subsite of CTP:phosphocholine cytidylyltransferase and choline kinase from Plasmodium falciparum. Comparison of quaternary ammonium binding site structures revealed a general composite aromatic box pattern of enzyme recognition sites, well distinguished from the aromatic box recognition site of receptors.
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Affiliation(s)
- Gergely N Nagy
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, 1111 Budapest (Hungary); Institute of Enzymology, Research Centre of National Sciences, HAS, 1117 Budapest (Hungary).
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Atherton J, Farabella I, Yu IM, Rosenfeld SS, Houdusse A, Topf M, Moores CA. Conserved mechanisms of microtubule-stimulated ADP release, ATP binding, and force generation in transport kinesins. eLife 2014; 3:e03680. [PMID: 25209998 PMCID: PMC4358365 DOI: 10.7554/elife.03680] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/08/2014] [Indexed: 01/21/2023] Open
Abstract
Kinesins are a superfamily of microtubule-based ATP-powered motors, important for multiple, essential cellular functions. How microtubule binding stimulates their ATPase and controls force generation is not understood. To address this fundamental question, we visualized microtubule-bound kinesin-1 and kinesin-3 motor domains at multiple steps in their ATPase cycles—including their nucleotide-free states—at ∼7 Å resolution using cryo-electron microscopy. In both motors, microtubule binding promotes ordered conformations of conserved loops that stimulate ADP release, enhance microtubule affinity and prime the catalytic site for ATP binding. ATP binding causes only small shifts of these nucleotide-coordinating loops but induces large conformational changes elsewhere that allow force generation and neck linker docking towards the microtubule plus end. Family-specific differences across the kinesin–microtubule interface account for the distinctive properties of each motor. Our data thus provide evidence for a conserved ATP-driven mechanism for kinesins and reveal the critical mechanistic contribution of the microtubule interface. DOI:http://dx.doi.org/10.7554/eLife.03680.001 The interior of a cell is a hive of activity, filled with proteins and other items moving from one location to another. A network of filaments called microtubules forms tracks along which so-called motor proteins carry these items. Kinesins are one group of motor proteins, and a typical kinesin protein has one end (called the ‘motor domain’) that can attach itself to the microtubules. The other end links to the cargo being carried, and a ‘neck’ connects the two. When two of these proteins work together, flexible regions of the neck allow the two motor domains to move past one another, which enable the kinesin to essentially walk along a microtubule in a stepwise manner. To take these steps along microtubules, each kinesin motor domain in the pair must undergo alternating cycles of tight association and release from their tracks. This cycle is coordinated by binding and breaking down a molecule called ATP, which also provides the energy needed to take the next step. How the cycle of loose and tight microtubule attachment is coordinated with the release of the breakdown products of ATP, and how the energy from the ATP molecule is converted into the force that moves the motor along the microtubule, has been unclear. Atherton et al. use a technique called cryo-electron microscopy to study—in more detail than previously seen—the structure of the motor domains of two types of kinesin called kinesin-1 and kinesin-3. Images were taken at different stages of the cycle used by the motor domains to extract the energy from ATP molecules. Although the two kinesins have been thought to move along the microtubule tracks in different ways, Atherton et al. find that the core mechanism used by their motor domains is the same. When a motor domain binds to the microtubule, its shape changes, first stimulating release of the breakdown products of ATP from the previous cycle. This release makes room for a new ATP molecule to bind. The structural changes caused by ATP binding are relatively small but produce larger changes in the flexible neck region that enable individual motor domains within a kinesin pair to co-ordinate their movement and move in a consistent direction. This mechanism involves tight coupling between track binding and fuel usage and makes kinesins highly efficient motors. The structures uncovered by Atherton et al. reveal a mechanism that links microtubule binding, the energy supplied to the motor domain and the force that moves the kinesin along a microtubule. Future work will clarify whether the key features observed in the motor domains of kinesin-1 and kinesin-3 are also found in other types of kinesin motors. DOI:http://dx.doi.org/10.7554/eLife.03680.002
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Affiliation(s)
- Joseph Atherton
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, United Kingdom
| | - Irene Farabella
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, United Kingdom
| | - I-Mei Yu
- Structural Motility, Institut Curie, Centre National de la Recherche Scientifique, Paris, France
| | - Steven S Rosenfeld
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, United States
| | - Anne Houdusse
- Structural Motility, Institut Curie, Centre National de la Recherche Scientifique, Paris, France
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, United Kingdom
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, United Kingdom
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37
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Swenson AM, Trivedi DV, Rauscher AA, Wang Y, Takagi Y, Palmer BM, Málnási-Csizmadia A, Debold EP, Yengo CM. Magnesium modulates actin binding and ADP release in myosin motors. J Biol Chem 2014; 289:23977-91. [PMID: 25006251 DOI: 10.1074/jbc.m114.562231] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We examined the magnesium dependence of five class II myosins, including fast skeletal muscle myosin, smooth muscle myosin, β-cardiac myosin (CMIIB), Dictyostelium myosin II (DdMII), and nonmuscle myosin IIA, as well as myosin V. We found that the myosins examined are inhibited in a Mg(2+)-dependent manner (0.3-9.0 mm free Mg(2+)) in both ATPase and motility assays, under conditions in which the ionic strength was held constant. We found that the ADP release rate constant is reduced by Mg(2+) in myosin V, smooth muscle myosin, nonmuscle myosin IIA, CMIIB, and DdMII, although the ADP affinity is fairly insensitive to Mg(2+) in fast skeletal muscle myosin, CMIIB, and DdMII. Single tryptophan probes in the switch I (Trp-239) and switch II (Trp-501) region of DdMII demonstrate these conserved regions of the active site are sensitive to Mg(2+) coordination. Cardiac muscle fiber mechanic studies demonstrate cross-bridge attachment time is increased at higher Mg(2+) concentrations, demonstrating that the ADP release rate constant is slowed by Mg(2+) in the context of an activated muscle fiber. Direct measurements of phosphate release in myosin V demonstrate that Mg(2+) reduces actin affinity in the M·ADP·Pi state, although it does not change the rate of phosphate release. Therefore, the Mg(2+) inhibition of the actin-activated ATPase activity observed in class II myosins is likely the result of Mg(2+)-dependent alterations in actin binding. Overall, our results suggest that Mg(2+) reduces the ADP release rate constant and rate of attachment to actin in both high and low duty ratio myosins.
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Affiliation(s)
- Anja M Swenson
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Darshan V Trivedi
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Anna A Rauscher
- the Department of Biochemistry, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Yuan Wang
- the Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405
| | - Yasuharu Takagi
- the Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Bradley M Palmer
- the Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405
| | - András Málnási-Csizmadia
- the Department of Biochemistry, Eötvös Loránd University, H-1117 Budapest, Hungary, the Hungarian Academy of Sciences-Eötvös Loránd University Molecular Biophysics Research Group, H-1117 Budapest, Hungary
| | - Edward P Debold
- the Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts 02210, and
| | - Christopher M Yengo
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033,
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Geng YZ, Liu SX, Ji Q, Yan S. Mechanical amplification mechanism of kinesin's β-domain. Arch Biochem Biophys 2013; 543:10-4. [PMID: 24374282 DOI: 10.1016/j.abb.2013.12.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/10/2013] [Accepted: 12/18/2013] [Indexed: 10/25/2022]
Abstract
Conventional kinesin's force generation process always takes place on the leading head and the generated force is transmitted to the trailing head through two neck linkers. To guarantee a strong force to be transmitted to the trailing head so that it can be detached from microtubule surface, the neck linker of the leading head must have a large enough forward displacement, which is proposed to be achieved by the amplifying function of the β-domain. However, the experimental result shows that the forward displacement of the β-domain itself appears too small. To elucidate the function of the β-domain, we make a detailed analysis of the mechanical relationship between the two motor heads and, based on the results of molecular dynamics simulation and mechanical analysis, we calculate the forward displacement of the neck linker of the leading head during the ATP binding induced motor head rotation. We show that β-domain achieves its amplifying function together with β0, so that neck linker can have a forward displacement during motor head rotation. This displacement of neck linker is large enough to cause detachment of the trailing head. Based on these results, a possible initiation mechanism of neck linker docking is proposed.
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Affiliation(s)
- Yi-Zhao Geng
- College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
| | - Shu-Xia Liu
- Institute of Biophysics, Hebei University of Technology, Tianjin 300401, China
| | - Qing Ji
- Institute of Biophysics, Hebei University of Technology, Tianjin 300401, China.
| | - Shiwei Yan
- College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China; Beijing Radiation Center, Beijing 100875, China.
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Nucleotide-dependent displacement and dynamics of the α-1 helix in kinesin revealed by site-directed spin labeling EPR. Biochem Biophys Res Commun 2013; 443:911-6. [PMID: 24361895 DOI: 10.1016/j.bbrc.2013.12.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 12/11/2013] [Indexed: 11/21/2022]
Abstract
In kinesin X-ray crystal structures, the N-terminal region of the α-1 helix is adjacent to the adenine ring of the bound nucleotide, while the C-terminal region of the helix is near the neck-linker (NL). Here, we monitor the displacement of the α-1 helix within a kinesin monomer bound to microtubules (MTs) in the presence or absence of nucleotides using site-directed spin labeling EPR. Kinesin was doubly spin-labeled at the α-1 and α-2 helices, and the resulting EPR spectrum showed dipolar broadening. The inter-helix distance distribution showed that 20% of the spins have a peak characteristic of 1.4-1.7 nm separation, which is similar to what is predicted from the X-ray crystal structure, albeit 80% were beyond the sensitivity limit (>2.5 nm) of the method. Upon MT binding, the fraction of kinesin exhibiting an inter-helix distance of 1.4-1.7 nm in the presence of AMPPNP (a non-hydrolysable ATP analog) and ADP was 20% and 25%, respectively. In the absence of nucleotide, this fraction increased to 40-50%. These nucleotide-induced changes in the fraction of kinesin undergoing displacement of the α-1 helix were found to be related to the fraction in which the NL undocked from the motor core. It is therefore suggested that a shift in the α-1 helix conformational equilibrium occurs upon nucleotide binding and release, and this shift controls NL docking onto the motor core.
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40
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Kiani FA, Fischer S. Stabilization of the ADP/metaphosphate intermediate during ATP hydrolysis in pre-power stroke myosin: quantitative anatomy of an enzyme. J Biol Chem 2013; 288:35569-80. [PMID: 24165121 DOI: 10.1074/jbc.m113.500298] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It has been proposed recently that ATP hydrolysis in ATPase enzymes proceeds via an initial intermediate in which the dissociated γ-phosphate of ATP is bound in the protein as a metaphosphate (PγO3(-)). A combined quantum/classical analysis of this dissociated nucleotide state inside myosin provides a quantitative understanding of how the enzyme stabilizes this unusual metaphosphate. Indeed, in vacuum, the energy of the ADP(3-) · PγO3(-) · Mg(2+) complex is much higher than that of the undissociated ATP(4-). The protein brings it to a surprisingly low value. Energy decomposition reveals how much each interaction in the protein stabilizes the metaphosphate state; backbone peptides of the P-loop contribute 50% of the stabilization energy, and the side chain of Lys-185(+) contributes 25%. This can be explained by the fact that these groups make strong favorable interactions with the α- and β-phosphates, thus favoring the charge distribution of the metaphosphate state over that of the ATP state. Further stabilization (16%) is achieved by a hydrogen bond between the backbone C=O of Ser-237 (on loop Switch-1) and a water molecule perfectly positioned to attack the PγO3(-) in the subsequent hydrolysis step. The planar and singly negative PγO3(-) is a much better target for the subsequent nucleophilic attack by a negatively charged OH(-) than the tetrahedral and doubly negative PγO4(2-) group of ATP. Therefore, we argue that the present mechanism of metaphosphate stabilization is common to the large family of nucleotide-hydrolyzing enzymes. Methodologically, this work presents a computational approach that allows us to obtain a truly quantitative conception of enzymatic strategy.
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Affiliation(s)
- Farooq Ahmad Kiani
- From the Computational Biochemistry Group, Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimerfeld 368, D-69120 Heidelberg, Germany
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Abstract
Dynein is a microtubule-based molecular motor that is involved in various biological functions, such as axonal transport, mitosis, and cilia/flagella movement. Although dynein was discovered 50 years ago, the progress of dynein research has been slow due to its large size and flexible structure. Recent progress in understanding the force-generating mechanism of dynein using x-ray crystallography, cryo-electron microscopy, and single molecule studies has provided key insight into the structure and mechanism of action of this complex motor protein.
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Affiliation(s)
- Masahide Kikkawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Cochran JC, Thompson ME, Kull FJ. Metal switch-controlled myosin II from Dictyostelium discoideum supports closure of nucleotide pocket during ATP binding coupled to detachment from actin filaments. J Biol Chem 2013; 288:28312-23. [PMID: 23960071 DOI: 10.1074/jbc.m113.466045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G-proteins, kinesins, and myosins are hydrolases that utilize a common protein fold and divalent metal cofactor (typically Mg(2+)) to coordinate purine nucleotide hydrolysis. The nucleoside triphosphorylase activities of these enzymes are activated through allosteric communication between the nucleotide-binding site and the activator/effector/polymer interface to convert the free energy of nucleotide hydrolysis into molecular switching (G-proteins) or force generation (kinesins and myosin). We have investigated the ATPase mechanisms of wild-type and the S237C mutant of non-muscle myosin II motor from Dictyostelium discoideum. The S237C substitution occurs in the conserved metal-interacting switch-1, and we show that this substitution modulates the actomyosin interaction based on the divalent metal present in solution. Surprisingly, S237C shows rapid basal steady-state Mg(2+)- or Mn(2+)-ATPase kinetics, but upon binding actin, its MgATPase is inhibited. This actin inhibition is relieved by Mn(2+), providing a direct and experimentally reversible linkage of switch-1 and the actin-binding cleft through the swapping of divalent metals in the reaction. Using pyrenyl-labeled F-actin, we demonstrate that acto·S237C undergoes slow and weak MgATP binding, which limits the rate of steady-state catalysis. Mn(2+) rescues this effect to near wild-type activity. 2'(3')-O-(N-Methylanthraniloyl)-ADP release experiments show the need for switch-1 interaction with the metal cofactor for tight ADP binding. Our results are consistent with strong reciprocal coupling of nucleoside triphosphate and F-actin binding and provide additional evidence for the allosteric communication pathway between the nucleotide-binding site and the filament-binding region.
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Affiliation(s)
- Jared C Cochran
- From the Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
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Kinesin-5: cross-bridging mechanism to targeted clinical therapy. Gene 2013; 531:133-49. [PMID: 23954229 DOI: 10.1016/j.gene.2013.08.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/29/2013] [Accepted: 08/02/2013] [Indexed: 12/28/2022]
Abstract
Kinesin motor proteins comprise an ATPase superfamily that works hand in hand with microtubules in every eukaryote. The mitotic kinesins, by virtue of their potential therapeutic role in cancerous cells, have been a major focus of research for the past 28 years since the discovery of the canonical Kinesin-1 heavy chain. Perhaps the simplest player in mitotic spindle assembly, Kinesin-5 (also known as Kif11, Eg5, or kinesin spindle protein, KSP) is a plus-end-directed motor localized to interpolar spindle microtubules and to the spindle poles. Comprised of a homotetramer complex, its function primarily is to slide anti-parallel microtubules apart from one another. Based on multi-faceted analyses of this motor from numerous laboratories over the years, we have learned a great deal about the function of this motor at the atomic level for catalysis and as an integrated element of the cytoskeleton. These data have, in turn, informed the function of motile kinesins on the whole, as well as spearheaded integrative models of the mitotic apparatus in particular and regulation of the microtubule cytoskeleton in general. We review what is known about how this nanomotor works, its place inside the cytoskeleton of cells, and its small-molecule inhibitors that provide a toolbox for understanding motor function and for anticancer treatment in the clinic.
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Trivedi DV, Muretta JM, Swenson AM, Thomas DD, Yengo CM. Magnesium impacts myosin V motor activity by altering key conformational changes in the mechanochemical cycle. Biochemistry 2013; 52:4710-22. [PMID: 23725637 DOI: 10.1021/bi4004364] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigated how magnesium (Mg) impacts key conformational changes during the ADP binding/release steps in myosin V and how these alterations impact the actomyosin mechanochemical cycle. The conformation of the nucleotide binding pocket was examined with our established FRET system in which myosin V labeled with FlAsH in the upper 50 kDa domain participates in energy transfer with mant labeled nucleotides. We examined the maximum actin-activated ATPase activity of MV FlAsH at a range of free Mg concentrations (0.1-9 mM) and found that the highest activity occurs at low Mg (0.1-0.3 mM), while there is a 50-60% reduction in activity at high Mg (3-9 mM). The motor activity examined with the in vitro motility assay followed a similar Mg-dependence, and the trend was similar with dimeric myosin V. Transient kinetic FRET studies of mantdADP binding/release from actomyosin V FlAsH demonstrate that the transition between the weak and strong actomyosin.ADP states is coupled to movement of the upper 50 kDa domain and is dependent on Mg with the strong state stabilized by Mg. We find that the kinetics of the upper 50 kDa conformational change monitored by FRET correlates well with the ATPase and motility results over a wide range of Mg concentrations. Our results suggest the conformation of the upper 50 kDa domain is highly dynamic in the Mg free actomyosin.ADP state, which is in agreement with ADP binding being entropy driven in the absence of Mg. Overall, our results demonstrate that Mg is a key factor in coupling the nucleotide- and actin-binding regions. In addition, Mg concentrations in the physiological range can alter the structural transition that limits ADP dissociation from actomyosin V, which explains the impact of Mg on actin-activated ATPase activity and in vitro motility.
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Affiliation(s)
- Darshan V Trivedi
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University , Hershey, Pennsylvania 17033, United States
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Kull FJ, Endow SA. Force generation by kinesin and myosin cytoskeletal motor proteins. J Cell Sci 2013; 126:9-19. [PMID: 23487037 DOI: 10.1242/jcs.103911] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Kinesins and myosins hydrolyze ATP, producing force that drives spindle assembly, vesicle transport and muscle contraction. How do motors do this? Here we discuss mechanisms of motor force transduction, based on their mechanochemical cycles and conformational changes observed in crystal structures. Distortion or twisting of the central β-sheet - proposed to trigger actin-induced Pi and ADP release by myosin, and microtubule-induced ADP release by kinesins - is shown in a movie depicting the transition between myosin ATP-like and nucleotide-free states. Structural changes in the switch I region form a tube that governs ATP hydrolysis and Pi release by the motors, explaining the essential role of switch I in hydrolysis. Comparison of the motor power strokes reveals that each stroke begins with the force-amplifying structure oriented opposite to the direction of rotation or swing. Motors undergo changes in their mechanochemical cycles in response to small-molecule inhibitors, several of which bind to kinesins by induced fit, trapping the motors in a state that resembles a force-producing conformation. An unusual motor activator specifically increases mechanical output by cardiac myosin, potentially providing valuable information about its mechanism of function. Further study is essential to understand motor mechanochemical coupling and energy transduction, and could lead to new therapies to treat human disease.
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Affiliation(s)
- F Jon Kull
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
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Roles for Helicases as ATP-Dependent Molecular Switches. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 767:225-44. [PMID: 23161014 DOI: 10.1007/978-1-4614-5037-5_11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
On the basis of the familial name, a "helicase" might be expected to have an enzymatic activity that unwinds duplex polynucleotides to form single strands. A more encompassing taxonomy that captures alternative enzymatic roles has defined helicases as a sub-class of molecular motors that move directionally and processively along nucleic acids, the so-called "translocases". However, even this definition may be limiting in capturing the full scope of helicase mechanism and activity. Discussed here is another, alternative view of helicases-as machines which couple NTP-binding and hydrolysis to changes in protein conformation to resolve stable nucleoprotein assembly states. This "molecular switch" role differs from the classical view of helicases as molecular motors in that only a single catalytic NTPase cycle may be involved. This is illustrated using results obtained with the DEAD-box family of RNA helicases and with a model bacterial system, the ATP-dependent Type III restriction-modification enzymes. Further examples are discussed and illustrate the wide-ranging examples of molecular switches in genome metabolism.
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There and back again: new single-molecule insights in the motion of DNA repair proteins. Curr Opin Struct Biol 2012; 23:154-60. [PMID: 23260129 DOI: 10.1016/j.sbi.2012.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/26/2012] [Accepted: 11/27/2012] [Indexed: 11/24/2022]
Abstract
Cellular DNA repair machines are constantly at work supporting the integrity of our genomes. Numerous proteins cooperate to form a complex and adaptive system dedicated to detection and timely processing of DNA damage. The molecular underpinnings of how these proteins locate and discriminate DNA lesions, match homologous sequences, mend the DNA and attend to a replication in distress are of a paramount biomedical importance, but in many cases remain unclear. Combined with more conventional tools, single-molecule biochemistry has been stepping in to address the age-old problems in the DNA repair field. This review will address new insights into diffusive properties of three DNA repair systems: I will discuss the emerging model of how MutS homologues locate and respond to mismatches in the dsDNA; the mechanism by which RAD52 promotes annealing of complementary DNA strands coated with ssDNA binding protein RPA; and how the nucleoprotein filament formed by RecA recombinase on ssDNA searches for homology within duplex DNA. These three distinct DNA repair factors exemplify the dynamic nature of cellular DNA repair machines revealed by single-molecule studies.
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Delorme C, Joshi M, Allingham JS. Crystal structure of the Candida albicans Kar3 kinesin motor domain fused to maltose-binding protein. Biochem Biophys Res Commun 2012; 428:427-32. [PMID: 23137538 DOI: 10.1016/j.bbrc.2012.10.101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 10/16/2012] [Indexed: 10/27/2022]
Abstract
In the human fungal pathogen Candida albicans, the Kinesin-14 motor protein Kar3 (CaKar3) is critical for normal mitotic division, nuclear fusion during mating, and morphogenic transition from the commensal yeast form to the virulent hyphal form. As a first step towards detailed characterization of this motor of potential medical significance, we have crystallized and determined the X-ray structure of the motor domain of CaKar3 as a maltose-binding protein (MBP) fusion. The structure shows strong conservation of overall motor domain topology to other Kar3 kinesins, but with some prominent differences in one of the motifs that compose the nucleotide-binding pocket and the surface charge distribution. The MBP and Kar3 modules are arranged such that MBP interacts with the Kar3 motor domain core at the same site where the neck linker of conventional kinesins docks during the "ATP state" of the mechanochemical cycle. This site differs from the Kar3 neck-core interface in the recent structure of the ScKar3Vik1 heterodimer. The position of MBP is also completely distinct from the Vik1 subunit in this complex. This may suggest that the site of MBP interaction on the CaKar3 motor domain provides an interface for the neck, or perhaps a partner subunit, at an intermediate state of its motile cycle that has not yet been observed for Kinesin-14 motors.
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Affiliation(s)
- Caroline Delorme
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada K7L 3N6
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Abstract
Kinesin molecular motors perform a myriad of intracellular transport functions. While their mechanochemical mechanisms are well understood and well-conserved throughout the superfamily, the cargo-binding and regulatory mechanisms governing the activity of kinesins are highly diverse and in general, are incompletely characterized. Here we present evidence from bioinformatic predictions indicating that most kinesin superfamily members contain significant regions of intrinsically disordered (ID) residues. ID regions can bind to multiple partners with high specificity, and are highly labile to post-translational modification and degradation signals. In kinesins, the predicted ID regions are primarily found in areas outside the motor domains, where primary sequences diverge by family, suggesting that ID may be a critical structural element for determining the functional specificity of individual kinesins. To support this idea, we present a systematic analysis of the kinesin superfamily, family by family, for predicted regions of ID. We combine this analysis with a comprehensive review of kinesin binding partners and post-translational modifications. We find two key trends across the entire kinesin superfamily. First, ID residues tend to be in the tail regions of kinesins, opposite the superfamily-conserved motor domains. Second, predicted ID regions correlate to regions that are known to bind to cargoes and/or undergo post-translational modifications. We therefore propose that ID is a structural element utilized by the kinesin superfamily in order to impart functional specificity to individual kinesins.
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Kamei T, Fukaminato T, Tamaoki N. A photochromic ATP analogue driving a motor protein with reversible light-controlled motility: controlling velocity and binding manner of a kinesin-microtubule system in an in vitro motility assay. Chem Commun (Camb) 2012; 48:7625-7. [PMID: 22735457 DOI: 10.1039/c2cc33552b] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We synthesized two photochromic ATP analogues (ATP-Azos) featuring azobenzene derivatives tethered at the 2' position of the ribose ring. In the presence of the ATP-Azo tethering p-tert-butylazobenzene, we observed reversible photo-control of the motility, velocity and binding manner, of a kinesin-microtubule system in an in vitro motility assay.
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Affiliation(s)
- Takashi Kamei
- Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo, Hokkaido, Japan
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