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Rynkiewicz MJ, Childers MC, Karpicheva OE, Regnier M, Geeves MA, Lehman W. Myosin's powerstroke transitions define atomic scale movement of cardiac thin filament tropomyosin. J Gen Physiol 2024; 156:e202413538. [PMID: 38607351 PMCID: PMC11010328 DOI: 10.1085/jgp.202413538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/27/2024] [Accepted: 03/28/2024] [Indexed: 04/13/2024] Open
Abstract
Dynamic interactions between the myosin motor head on thick filaments and the actin molecular track on thin filaments drive the myosin-crossbridge cycle that powers muscle contraction. The process is initiated by Ca2+ and the opening of troponin-tropomyosin-blocked myosin-binding sites on actin. The ensuing recruitment of myosin heads and their transformation from pre-powerstroke to post-powerstroke conformation on actin produce the force required for contraction. Cryo-EM-based atomic models confirm that during this process, tropomyosin occupies three different average positions on actin. Tropomyosin pivoting on actin away from a TnI-imposed myosin-blocking position accounts for part of the Ca2+ activation observed. However, the structure of tropomyosin on thin filaments that follows pre-powerstroke myosin binding and its translocation during myosin's pre-powerstroke to post-powerstroke transition remains unresolved. Here, we approach this transition computationally in silico. We used the myosin helix-loop-helix motif as an anchor to dock models of pre-powerstroke cardiac myosin to the cleft between neighboring actin subunits along cardiac thin filaments. We then performed targeted molecular dynamics simulations of the transition between pre- and post-powerstroke conformations on actin in the presence of cardiac troponin-tropomyosin. These simulations show Arg 369 and Glu 370 on the tip of myosin Loop-4 encountering identically charged residues on tropomyosin. The charge repulsion between residues causes tropomyosin translocation across actin, thus accounting for the final regulatory step in the activation of the thin filament, and, in turn, facilitating myosin movement along the filament. We suggest that during muscle activity, myosin-induced tropomyosin movement is likely to result in unencumbered myosin head interactions on actin at low-energy cost.
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Affiliation(s)
- Michael J. Rynkiewicz
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, USA
| | | | - Olga E. Karpicheva
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, USA
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | | | - William Lehman
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, USA
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Gong R, Jiang F, Moreland ZG, Reynolds MJ, de los Reyes SE, Gurel P, Shams A, Heidings JB, Bowl MR, Bird JE, Alushin GM. Structural basis for tunable control of actin dynamics by myosin-15 in mechanosensory stereocilia. SCIENCE ADVANCES 2022; 8:eabl4733. [PMID: 35857845 PMCID: PMC9299544 DOI: 10.1126/sciadv.abl4733] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 06/03/2022] [Indexed: 05/12/2023]
Abstract
The motor protein myosin-15 is necessary for the development and maintenance of mechanosensory stereocilia, and mutations in myosin-15 cause hereditary deafness. In addition to transporting actin regulatory machinery to stereocilia tips, myosin-15 directly nucleates actin filament ("F-actin") assembly, which is disrupted by a progressive hearing loss mutation (p.D1647G, "jordan"). Here, we present cryo-electron microscopy structures of myosin-15 bound to F-actin, providing a framework for interpreting the impacts of deafness mutations on motor activity and actin nucleation. Rigor myosin-15 evokes conformational changes in F-actin yet maintains flexibility in actin's D-loop, which mediates inter-subunit contacts, while the jordan mutant locks the D-loop in a single conformation. Adenosine diphosphate-bound myosin-15 also locks the D-loop, which correspondingly blunts actin-polymerization stimulation. We propose myosin-15 enhances polymerization by bridging actin protomers, regulating nucleation efficiency by modulating actin's structural plasticity in a myosin nucleotide state-dependent manner. This tunable regulation of actin polymerization could be harnessed to precisely control stereocilium height.
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Affiliation(s)
- Rui Gong
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Fangfang Jiang
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Zane G. Moreland
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Matthew J. Reynolds
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | | | - Pinar Gurel
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Arik Shams
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | - James B. Heidings
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Michael R. Bowl
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Campus, Oxfordshire, UK
- UCL Ear Institute, University College London, London, UK
| | - Jonathan E. Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Gregory M. Alushin
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
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3
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Doran MH, Lehman W. The Central Role of the F-Actin Surface in Myosin Force Generation. BIOLOGY 2021; 10:1221. [PMID: 34943138 PMCID: PMC8698748 DOI: 10.3390/biology10121221] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/17/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022]
Abstract
Actin is one of the most abundant and versatile proteins in eukaryotic cells. As discussed in many contributions to this Special Issue, its transition from a monomeric G-actin to a filamentous F-actin form plays a critical role in a variety of cellular processes, including control of cell shape and cell motility. Once polymerized from G-actin, F-actin forms the central core of muscle-thin filaments and acts as molecular tracks for myosin-based motor activity. The ATP-dependent cross-bridge cycle of myosin attachment and detachment drives the sliding of myosin thick filaments past thin filaments in muscle and the translocation of cargo in somatic cells. The variation in actin function is dependent on the variation in muscle and non-muscle myosin isoform behavior as well as interactions with a plethora of additional actin-binding proteins. Extensive work has been devoted to defining the kinetics of actin-based force generation powered by the ATPase activity of myosin. In addition, over the past decade, cryo-electron microscopy has revealed the atomic-evel details of the binding of myosin isoforms on the F-actin surface. Most accounts of the structural interactions between myosin and actin are described from the perspective of the myosin molecule. Here, we discuss myosin-binding to actin as viewed from the actin surface. We then describe conserved structural features of actin required for the binding of all or most myosin isoforms while also noting specific interactions unique to myosin isoforms.
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Affiliation(s)
- Matthew H. Doran
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
| | - William Lehman
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
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Ewert W, Franz P, Tsiavaliaris G, Preller M. Structural and Computational Insights into a Blebbistatin-Bound Myosin•ADP Complex with Characteristics of an ADP-Release Conformation along the Two-Step Myosin Power Stoke. Int J Mol Sci 2020; 21:ijms21197417. [PMID: 33049993 PMCID: PMC7582316 DOI: 10.3390/ijms21197417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 10/06/2020] [Indexed: 01/13/2023] Open
Abstract
The motor protein myosin drives a wide range of cellular and muscular functions by generating directed movement and force, fueled through adenosine triphosphate (ATP) hydrolysis. Release of the hydrolysis product adenosine diphosphate (ADP) is a fundamental and regulatory process during force production. However, details about the molecular mechanism accompanying ADP release are scarce due to the lack of representative structures. Here we solved a novel blebbistatin-bound myosin conformation with critical structural elements in positions between the myosin pre-power stroke and rigor states. ADP in this structure is repositioned towards the surface by the phosphate-sensing P-loop, and stabilized in a partially unbound conformation via a salt-bridge between Arg131 and Glu187. A 5 Å rotation separates the mechanical converter in this conformation from the rigor position. The crystallized myosin structure thus resembles a conformation towards the end of the two-step power stroke, associated with ADP release. Computationally reconstructing ADP release from myosin by means of molecular dynamics simulations further supported the existence of an equivalent conformation along the power stroke that shows the same major characteristics in the myosin motor domain as the resolved blebbistatin-bound myosin-II·ADP crystal structure, and identified a communication hub centered on Arg232 that mediates chemomechanical energy transduction.
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Affiliation(s)
- Wiebke Ewert
- Institute for Biophysical Chemistry, Structural Bioinformatics and Chemical Biology, Hannover Medical School, 30625 Hannover, Germany;
| | - Peter Franz
- Institute for Biophysical Chemistry, Cellular Biophysics, Hannover Medical School, 30625 Hannover, Germany; (P.F.); (G.T.)
| | - Georgios Tsiavaliaris
- Institute for Biophysical Chemistry, Cellular Biophysics, Hannover Medical School, 30625 Hannover, Germany; (P.F.); (G.T.)
| | - Matthias Preller
- Institute for Biophysical Chemistry, Structural Bioinformatics and Chemical Biology, Hannover Medical School, 30625 Hannover, Germany;
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, 53359 Rheinbach, Germany
- Correspondence: ; Tel.: +49-511-532-2804
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Bibó A, Károlyi G, Kovács M. Unrevealed part of myosin's powerstroke accounts for high efficiency of muscle contraction. Biochim Biophys Acta Gen Subj 2017; 1861:2325-2333. [DOI: 10.1016/j.bbagen.2017.05.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 05/02/2017] [Accepted: 05/24/2017] [Indexed: 11/30/2022]
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Oshima H, Hayashi T, Kinoshita M. Statistical Thermodynamics for Actin-Myosin Binding: The Crucial Importance of Hydration Effects. Biophys J 2017; 110:2496-2506. [PMID: 27276267 DOI: 10.1016/j.bpj.2016.05.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 01/01/2023] Open
Abstract
Actomyosin is an important molecular motor, and the binding of actin and myosin is an essential research target in biophysics. Nevertheless, the physical factors driving or opposing the binding are still unclear. Here, we investigate the role of water in actin-myosin binding using the most reliable statistical-mechanical method currently available for assessing biomolecules immersed in water. This method is characterized as follows: water is treated not as a dielectric continuum but as an ensemble of molecules; the polyatomic structures of proteins are taken into consideration; and the binding free energy is decomposed into physically insightful entropic and energetic components by accounting for the hydration effect to its full extent. We find that the actin-myosin binding brings large gains of electrostatic and Lennard-Jones attractive interactions. However, these gains are accompanied by even larger losses of actin-water and myosin-water electrostatic and LJ attractive interactions. Although roughly half of the energy increase due to the losses is cancelled out by the energy decrease arising from structural reorganization of the water released upon binding, the remaining energy increase is still larger than the energy decrease brought by the gains mentioned above. Hence, the net change in system energy is positive, which opposes binding. Importantly, the binding is driven by a large gain of configurational entropy of water, which surpasses the positive change in system energy and the conformational entropy loss occurring for actin and myosin. The principal physical origin of the large water-entropy gain is as follows: the actin-myosin interface is closely packed with the achievement of high shape complementarity on the atomic level, leading to a large increase in the total volume available to the translational displacement of water molecules in the system and a resultant reduction of water crowding (i.e., entropic correlations among water molecules).
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Affiliation(s)
- Hiraku Oshima
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan
| | - Tomohiko Hayashi
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan
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Sato T, Ohnuki J, Takano M. Dielectric Allostery of Protein: Response of Myosin to ATP Binding. J Phys Chem B 2016; 120:13047-13055. [PMID: 28030954 DOI: 10.1021/acs.jpcb.6b10003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein uses allostery to execute biological function. The physical mechanism underlying the allostery has long been studied, with the focus on the mechanical response by ligand binding. Here, we highlight the electrostatic response, presenting an idea of "dielectric allostery". We conducted molecular dynamics simulations of myosin, a motor protein with allostery, and analyzed the response to ATP binding which is a crucial step in force-generating function, forcing myosin to unbind from the actin filament. We found that the net negative charge of ATP causes a large-scale, anisotropic dielectric response in myosin, altering the electrostatic potential in the distant actin-binding region and accordingly retracting a positively charged actin-binding loop. A large-scale rearrangement of electrostatic bond network was found to occur upon ATP binding. Since proteins are dielectric and ligands are charged/polar in general, the dielectric allostery might underlie a wide spectrum of functions by proteins.
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Affiliation(s)
- Takato Sato
- Department of Pure and Applied Physics, Waseda University , Okubo 3-4-1, Shinjuku-Ku, Tokyo 169-8555, Japan
| | - Jun Ohnuki
- Department of Pure and Applied Physics, Waseda University , Okubo 3-4-1, Shinjuku-Ku, Tokyo 169-8555, Japan
| | - Mitsunori Takano
- Department of Pure and Applied Physics, Waseda University , Okubo 3-4-1, Shinjuku-Ku, Tokyo 169-8555, Japan
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Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution. Nature 2016; 534:724-8. [PMID: 27324845 DOI: 10.1038/nature18295] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/29/2016] [Indexed: 12/12/2022]
Abstract
The interaction of myosin with actin filaments is the central feature of muscle contraction and cargo movement along actin filaments of the cytoskeleton. The energy for these movements is generated during a complex mechanochemical reaction cycle. Crystal structures of myosin in different states have provided important structural insights into the myosin motor cycle when myosin is detached from F-actin. The difficulty of obtaining diffracting crystals, however, has prevented structure determination by crystallography of actomyosin complexes. Thus, although structural models exist of F-actin in complex with various myosins, a high-resolution structure of the F-actin–myosin complex is missing. Here, using electron cryomicroscopy, we present the structure of a human rigor actomyosin complex at an average resolution of 3.9 Å. The structure reveals details of the actomyosin interface, which is mainly stabilized by hydrophobic interactions. The negatively charged amino (N) terminus of actin interacts with a conserved basic motif in loop 2 of myosin, promoting cleft closure in myosin. Surprisingly, the overall structure of myosin is similar to rigor-like myosin structures in the absence of F-actin, indicating that F-actin binding induces only minimal conformational changes in myosin. A comparison with pre-powerstroke and intermediate (Pi-release) states of myosin allows us to discuss the general mechanism of myosin binding to F-actin. Our results serve as a strong foundation for the molecular understanding of cytoskeletal diseases, such as autosomal dominant hearing loss and diseases affecting skeletal and cardiac muscles, in particular nemaline myopathy and hypertrophic cardiomyopathy.
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Matsuo T, Arata T, Oda T, Nakajima K, Ohira-Kawamura S, Kikuchi T, Fujiwara S. Internal dynamics of F-actin and myosin subfragment-1 studied by quasielastic neutron scattering. Biochem Biophys Res Commun 2015; 459:493-7. [PMID: 25747714 DOI: 10.1016/j.bbrc.2015.02.134] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 02/24/2015] [Indexed: 11/15/2022]
Abstract
Various biological functions related to cell motility are driven by the interaction between the partner proteins, actin and myosin. To obtain insights into how this interaction occurs, the internal dynamics of F-actin and myosin subfragment-1 (S1) were characterized by the quasielastic neutron scattering measurements on the solution samples of F-actin and S1. Contributions of the internal motions of the proteins to the scattering spectra were separated from those of the global macromolecular diffusion. Analysis of the spectra arising from the internal dynamics showed that the correlation times of the atomic motions were about two times shorter for F-actin than for S1, suggesting that F-actin fluctuates more rapidly than S1. It was also shown that the fraction of the immobile atoms is larger for S1 than for F-actin. These results suggest that F-actin actively facilitates the binding of myosin by utilizing the more frequent conformational fluctuations than those of S1.
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Affiliation(s)
- Tatsuhito Matsuo
- Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Toshiaki Arata
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Toshiro Oda
- Graduate School of Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Kenji Nakajima
- Neutron Science Section, J-PARC Center, Tokai, Ibaraki 319-1195, Japan
| | | | - Tatsuya Kikuchi
- Neutron Science Section, J-PARC Center, Tokai, Ibaraki 319-1195, Japan
| | - Satoru Fujiwara
- Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
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