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Hojjatian A, Taylor DW, Daneshparvar N, Fagnant PM, Trybus KM, Taylor KA. Double-headed binding of myosin II to F-actin shows the effect of strain on head structure. J Struct Biol 2023; 215:107995. [PMID: 37414375 PMCID: PMC10544818 DOI: 10.1016/j.jsb.2023.107995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/25/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023]
Abstract
Force production in muscle is achieved through the interaction of myosin and actin. Strong binding states in active muscle are associated with Mg·ADP bound to the active site; release of Mg·ADP allows rebinding of ATP and dissociation from actin. Thus, Mg·ADP binding is positioned for adaptation as a force sensor. Mechanical loads on the lever arm can affect the ability of myosin to release Mg·ADP but exactly how this is done is poorly defined. Here we use F-actin decorated with double-headed smooth muscle myosin fragments in the presence of Mg·ADP to visualize the effect of internally supplied tension on the paired lever arms using cryoEM. The interaction of the paired heads with two adjacent actin subunits is predicted to place one lever arm under positive and the other under negative strain. The converter domain is believed to be the most flexible domain within myosin head. Our results, instead, point to the segment of heavy chain between the essential and regulatory light chains as the location of the largest structural change. Moreover, our results suggest no large changes in the myosin coiled coil tail as the locus of strain relief when both heads bind F-actin. The method would be adaptable to double-headed members of the myosin family. We anticipate that the study of actin-myosin interaction using double-headed fragments enables visualization of domains that are typically noisy in decoration with single-headed fragments.
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Affiliation(s)
- Alimohammad Hojjatian
- Inst. of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States
| | - Dianne W Taylor
- Inst. of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States
| | - Nadia Daneshparvar
- Inst. of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States
| | - Patricia M Fagnant
- Dept of Molecular Physiology & Biophysics, University of Vermont College of Medicine, Burlington, VT 05405, United States
| | - Kathleen M Trybus
- Dept of Molecular Physiology & Biophysics, University of Vermont College of Medicine, Burlington, VT 05405, United States
| | - Kenneth A Taylor
- Inst. of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, United States.
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2
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Do Actomyosin Single-Molecule Mechanics Data Predict Mechanics of Contracting Muscle? Int J Mol Sci 2018; 19:ijms19071863. [PMID: 29941816 PMCID: PMC6073448 DOI: 10.3390/ijms19071863] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 12/15/2022] Open
Abstract
In muscle, but not in single-molecule mechanics studies, actin, myosin and accessory proteins are incorporated into a highly ordered myofilament lattice. In view of this difference we compare results from single-molecule studies and muscle mechanics and analyze to what degree data from the two types of studies agree with each other. There is reasonable correspondence in estimates of the cross-bridge power-stroke distance (7–13 nm), cross-bridge stiffness (~2 pN/nm) and average isometric force per cross-bridge (6–9 pN). Furthermore, models defined on the basis of single-molecule mechanics and solution biochemistry give good fits to experimental data from muscle. This suggests that the ordered myofilament lattice, accessory proteins and emergent effects of the sarcomere organization have only minor modulatory roles. However, such factors may be of greater importance under e.g., disease conditions. We also identify areas where single-molecule and muscle data are conflicting: (1) whether force generation is an Eyring or Kramers process with just one major power-stroke or several sub-strokes; (2) whether the myofilaments and the cross-bridges have Hookean or non-linear elasticity; (3) if individual myosin heads slip between actin sites under certain conditions, e.g., in lengthening; or (4) if the two heads of myosin cooperate.
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3
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Pfuhl M, Gautel M. Structure, interactions and function of the N-terminus of cardiac myosin binding protein C (MyBP-C): who does what, with what, and to whom? J Muscle Res Cell Motil 2012; 33:83-94. [PMID: 22527637 DOI: 10.1007/s10974-012-9291-z] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 03/24/2012] [Indexed: 02/04/2023]
Abstract
The thick filament protein myosin-binding protein-C shows a highly modular architecture, with the C-terminal region responsible for tethering to the myosin and titin backbone of the thick filament. The N-terminal region shows the most significant differences between cardiac and skeletal muscle isogenes: an entire Ig-domain (C0) is added, together with highly regulated phosphorylation sites between Ig domains C1 and C2. These structural and functional differences at the N-terminus reflect important functions in cardiac muscle regulation in health and disease. Alternative interactions of this part of MyBP-C with the head-tail (S1-S2) junction of myosin or to actin filaments have been proposed, but with conflicting experimental evidence. The regulation of myosin or actin interaction by phosphorylation of the cardiac MyBP-C N-terminus may play an additional role in length-dependent contraction regulation. We discuss here the evidence for these proposed interactions, considering the required properties of MyBP-C, the way in which they may be regulated in muscle contraction and the way they might be related to heart disease. We also attempt to shed some light on experimental pitfalls and future strategies.
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Affiliation(s)
- Mark Pfuhl
- Randall Division for Cell and Molecular Biophysics and Cardiovascular Division, King's College London BHF Centre of Research Excellence, London, UK.
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4
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Månsson A. Significant impact on muscle mechanics of small nonlinearities in myofilament elasticity. Biophys J 2010; 99:1869-75. [PMID: 20858432 PMCID: PMC2941020 DOI: 10.1016/j.bpj.2010.07.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Revised: 07/12/2010] [Accepted: 07/16/2010] [Indexed: 11/23/2022] Open
Abstract
Important mechanisms in muscle contraction have recently been reevaluated based on analyses that rely on the assumption of linear myofilament elasticity. However, the present theoretical study shows that nonlinearity of this elasticity, even when so minor that it may be difficult to detect in experimental data, could have great impact on the interpretation of muscle mechanical experiments. This is illustrated by using simulated stiffness and strain-versus-force data for muscle fibers shortening at different constant velocities. There is substantial quantitative agreement, for this condition, between models with distributed myofilament compliance and models where the compliance of the myofilaments and the actomyosin cross-bridges are lumped together into two separate elastic elements acting in series. The data thus support the usefulness of the latter, simpler, type of model in the analysis. However, most importantly, the data emphasize the importance of caution before reevaluating fundamental mechanisms of muscle contraction based on analyses relying on the assumption of linear myofilament elasticity.
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Affiliation(s)
- Alf Månsson
- School of Natural Sciences, Linnaeus University, Kalmar, Sweden.
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5
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Amrute‐Nayak M, Diensthuber R, Steffen W, Kathmann D, Hartmann F, Fedorov R, Urbanke C, Manstein D, Brenner B, Tsiavaliaris G. Targeted Optimization of a Protein Nanomachine for Operation in Biohybrid Devices. Angew Chem Int Ed Engl 2010; 49:312-6. [DOI: 10.1002/anie.200905200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mamta Amrute‐Nayak
- Institut für Molekular‐ und Zellphysiologie OE4350, Medizinische Hochschule Hannover (Germany)
| | - Ralph P. Diensthuber
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Walter Steffen
- Institut für Molekular‐ und Zellphysiologie OE4350, Medizinische Hochschule Hannover (Germany)
| | - Daniela Kathmann
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Falk K. Hartmann
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Roman Fedorov
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Claus Urbanke
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Dietmar J. Manstein
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Bernhard Brenner
- Institut für Molekular‐ und Zellphysiologie OE4350, Medizinische Hochschule Hannover (Germany)
| | - Georgios Tsiavaliaris
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
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6
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Amrute‐Nayak M, Diensthuber R, Steffen W, Kathmann D, Hartmann F, Fedorov R, Urbanke C, Manstein D, Brenner B, Tsiavaliaris G. Targeted Optimization of a Protein Nanomachine for Operation in Biohybrid Devices. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200905200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mamta Amrute‐Nayak
- Institut für Molekular‐ und Zellphysiologie OE4350, Medizinische Hochschule Hannover (Germany)
| | - Ralph P. Diensthuber
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Walter Steffen
- Institut für Molekular‐ und Zellphysiologie OE4350, Medizinische Hochschule Hannover (Germany)
| | - Daniela Kathmann
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Falk K. Hartmann
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Roman Fedorov
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Claus Urbanke
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Dietmar J. Manstein
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
| | - Bernhard Brenner
- Institut für Molekular‐ und Zellphysiologie OE4350, Medizinische Hochschule Hannover (Germany)
| | - Georgios Tsiavaliaris
- Institut für Biophysikalische Chemie OE4350, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, 30623 Hannover (Germany), Fax: (+49) 511‐532‐5966 http://www.mh‐hannover.de/bpc_uncmyo.html
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7
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Adamovic I, Mijailovich SM, Karplus M. The elastic properties of the structurally characterized myosin II S2 subdomain: a molecular dynamics and normal mode analysis. Biophys J 2008; 94:3779-89. [PMID: 18234833 PMCID: PMC2367198 DOI: 10.1529/biophysj.107.122028] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Accepted: 12/14/2007] [Indexed: 11/18/2022] Open
Abstract
The elastic properties (stretching and bending moduli) of myosin are expected to play an important role in its function. Of particular interest is the extended alpha-helical coiled-coil portion of the molecule. Since there is no high resolution structure for the entire coiled-coil, a study is made of the scallop myosin II S2 subdomain for which an x-ray structure is available (Protein Data Bank 1nkn). We estimate the stretching and bending moduli of the S2 subdomain with an atomic level model by use of molecular simulations. Results were obtained from nonequilibrium molecular dynamics simulations in the presence of an external force, from the fluctuations in equilibrium molecular dynamics simulations and from normal modes. In addition, a poly-Ala (78 amino acid residues) alpha-helix model was examined to test the methodology and because of its interest as part of the lever arm. As expected, both the alpha-helix and coiled-coil S2 subdomain are very stiff for stretching along the main axis, with the stretching stiffness constant in the range 60-80 pN/nm (scaled to the 60 nm long S2). Both molecules are much more flexible for bending with a lateral stiffness of approximately 0.010 pN/nm for the S2 and 0.0055 pN/nm for the alpha-helix (scaled to 60 nm). These results are expected to be useful in estimating cross-bridge elasticity, which is required for understanding the strain-dependent transitions in the actomyosin cycle and for the development of three-dimensional models of muscle contraction.
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Affiliation(s)
- Ivana Adamovic
- Harvard School of Public Health, Boston, Massachusetts 02115, USA
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8
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Brown JH, Yang Y, Reshetnikova L, Gourinath S, Süveges D, Kardos J, Hóbor F, Reutzel R, Nyitray L, Cohen C. An unstable head-rod junction may promote folding into the compact off-state conformation of regulated myosins. J Mol Biol 2008; 375:1434-43. [PMID: 18155233 PMCID: PMC2665131 DOI: 10.1016/j.jmb.2007.11.071] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 11/19/2007] [Accepted: 11/20/2007] [Indexed: 11/24/2022]
Abstract
The N-terminal region of myosin's rod-like subfragment 2 (S2) joins the two heads of this dimeric molecule and is key to its function. Previously, a crystal structure of this predominantly coiled-coil region was determined for a short fragment (51 residues plus a leucine zipper) of the scallop striated muscle myosin isoform. In that study, the N-terminal 10-14 residues were found to be disordered. We have now determined the structure of the same scallop peptide in three additional crystal environments. In each of two of these structures, improved order has allowed visualization of the entire N-terminus in one chain of the dimeric peptide. We have also compared the melting temperatures of this scallop S2 peptide with those of analogous peptides from three other isoforms. Taken together, these experiments, along with examination of sequences, point to a diminished stability of the N-terminal region of S2 in regulated myosins, compared with those myosins whose regulation is thin filament linked. It seems plain that this isoform-specific instability promotes the off-state conformation of the heads in regulated myosins. We also discuss how myosin isoforms with varied thermal stabilities share the basic capacity to transmit force efficiently in order to produce contraction in their on states.
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Affiliation(s)
- Jerry H. Brown
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110 USA
| | - Yuting Yang
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110 USA
| | - Ludmilla Reshetnikova
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110 USA
| | - S. Gourinath
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110 USA
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Dániel Süveges
- Department of Biochemistry, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/C, Hungary
| | - József Kardos
- Department of Biochemistry, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/C, Hungary
| | - Fruzsina Hóbor
- Department of Biochemistry, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/C, Hungary
| | - Robbie Reutzel
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110 USA
| | - László Nyitray
- Department of Biochemistry, Eötvös Loránd University, H-1117 Budapest, Pázmány P. s. 1/C, Hungary
| | - Carolyn Cohen
- Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110 USA
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9
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Blankenfeldt W, Thomä NH, Wray JS, Gautel M, Schlichting I. Crystal structures of human cardiac beta-myosin II S2-Delta provide insight into the functional role of the S2 subfragment. Proc Natl Acad Sci U S A 2006; 103:17713-7. [PMID: 17095604 PMCID: PMC1693812 DOI: 10.1073/pnas.0606741103] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myosin II is the major component of the muscle thick filament. It consists of two N-terminal S1 subfragments ("heads") connected to a long dimeric coiled-coil rod. The rod is in itself twofold symmetric, but in the filament, the two heads point away from the filament surface and are therefore not equivalent. This breaking of symmetry requires the initial section of the rod, subfragment 2 (S2), to be relatively flexible. S2 is an important functional element, involved in various mechanisms by which the activity of smooth and striated muscle is regulated. We have determined crystal structures of the 126 N-terminal residues of S2 from human cardiac beta-myosin II (S2-Delta), of both WT and the disease-associated E924K mutant. S2-Delta is a straight parallel dimeric coiled coil, but the N terminus of one chain is disordered in WT-S2-Delta due to crystal contacts, indicative of unstable local structure. Bulky noncanonical side chains pack into a/d positions of S2-Delta's N terminus, leading to defined local asymmetry and axial stagger, which could induce nonequivalence of the S1 subfragments. Additionally, S2 possesses a conserved charge distribution with three prominent rings of negative potential within S2-Delta, the first of which may provide a binding interface for the "blocked head" of smooth muscle myosin in the OFF state. The observation that many disease-associated mutations affect the second negatively charged ring further suggests that charge interactions play an important role in regulation of cardiac muscle activity through myosin-binding protein C.
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Affiliation(s)
- Wulf Blankenfeldt
- *Max Planck Institute of Molecular Physiology, Department of Physical Biochemistry, 44227 Dortmund, Germany
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, 69120 Heidelberg, Germany; and
- To whom correspondence may be addressed. E-mail:
or
| | - Nicolas H. Thomä
- *Max Planck Institute of Molecular Physiology, Department of Physical Biochemistry, 44227 Dortmund, Germany
| | - John S. Wray
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, 69120 Heidelberg, Germany; and
| | - Mathias Gautel
- *Max Planck Institute of Molecular Physiology, Department of Physical Biochemistry, 44227 Dortmund, Germany
- King's College London, Department of Muscle Cell Biology, The Randall Centre, New Hunt's House, SE 1 UL London, United Kingdom
| | - Ilme Schlichting
- *Max Planck Institute of Molecular Physiology, Department of Physical Biochemistry, 44227 Dortmund, Germany
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, 69120 Heidelberg, Germany; and
- To whom correspondence may be addressed. E-mail:
or
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10
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Oku T, Itoh S, Ishii R, Suzuki K, Nauseef W, Toyoshima S, Tsuji T. Homotypic dimerization of the actin-binding protein p57/coronin-1 mediated by a leucine zipper motif in the C-terminal region. Biochem J 2005; 387:325-31. [PMID: 15601263 PMCID: PMC1134960 DOI: 10.1042/bj20041020] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The actin-binding protein p57/coronin-1, a member of the coronin protein family, is selectively expressed in immune cells, and has been implicated in leucocyte migration and phagocytosis by virtue of its interaction with F-actin (filamentous actin). We previously identified two sites in the N-terminal region of p57/coronin-1 by which it binds actin, and in the present study we examine the role of the leucine zipper motif located in the C-terminal coiled-coil domain in mediating the homotypic association of p57/coronin-1. Recombinant p57/coronin-1 protein in solution formed a homodimer, as analysed by Superose 12 column chromatography and by sucrose density gradient centrifugation. In vivo, a truncated form consisting of the C-terminal coiled-coil domain co-precipitated with full-length p57/coronin-1 when both were co-expressed in COS-1 cells. A chimaeric construct composed of the C-terminal domain of p57/coronin-1 (which lacks the actin-binding sites) fused with green fluorescent protein co-localized with cortical F-actin-rich regions in COS-1 cells only when full-length p57/coronin-1 was expressed simultaneously in the cells, suggesting that the C-terminal region is required for the homotypic association of p57/coronin-1. Furthermore, p57LZ, a polypeptide consisting of the C-terminal 90 amino acid residues of p57/coronin-1, was sufficient for dimerization. When two leucine residues out of the four that constitute the leucine zipper structure in p57LZ or full-length p57 were replaced with alanine residues, the mutants failed to form homodimers. Taken together, these results demonstrate that p57/coronin-1 forms homodimers, that the association is mediated by the leucine zipper structure in the C-terminal region, and that it plays a role in the cross-linking of F-actin in the cell.
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Affiliation(s)
- Teruaki Oku
- *Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Saotomo Itoh
- *Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Rie Ishii
- *Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Kensuke Suzuki
- †Pharmaceutical Frontier Research Laboratories, Japan Tobacco Inc., 1-13-2 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan
| | - William M. Nauseef
- ‡The Inflammation Program and Department of Medicine, University of Iowa and Veterans Affairs Medical Center, Iowa City, IA 52242, U.S.A
| | - Satoshi Toyoshima
- §Pharmaceutical and Medical Device Evaluation Center, National Institute of Health Science, 3-8-21 Toranomon, Minato-ku, Tokyo 105-8409, Japan
| | - Tsutomu Tsuji
- *Department of Microbiology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
- To whom correspondence should be addressed (email )
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11
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Quinlan ME, Forkey JN, Goldman YE. Orientation of the myosin light chain region by single molecule total internal reflection fluorescence polarization microscopy. Biophys J 2005; 89:1132-42. [PMID: 15894631 PMCID: PMC1366598 DOI: 10.1529/biophysj.104.053496] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Accepted: 04/27/2005] [Indexed: 11/18/2022] Open
Abstract
To study the orientation and dynamics of myosin, we measured fluorescence polarization of single molecules and ensembles of myosin decorating actin filaments. Engineered chicken gizzard regulatory light chain (RLC), labeled with bisiodoacetamidorhodamine at cysteine residues 100 and 108 or 104 and 115, was exchanged for endogenous RLC in rabbit skeletal muscle HMM or S1. AEDANS-labeled actin, fully decorated with labeled myosin fragment or a ratio of approximately 1:1000 labeled:unlabeled myosin fragment, was adhered to a quartz slide. Eight polarized fluorescence intensities were combined with the actin orientation from the AEDANS fluorescence to determine the axial angle (relative to actin), the azimuthal angle (around actin), and RLC mobility on the <<10 ms timescale. Order parameters of the orientation distributions from heavily labeled filaments agree well with comparable measurements in muscle fibers, verifying the technique. Experiments with HMM provide sufficient angular resolution to detect two orientations corresponding to the two heads in rigor. Experiments with S1 show a single orientation intermediate to the two seen for HMM. The angles measured for HMM are consistent with heads bound on adjacent actin monomers of a filament, under strain, similar to predictions based on ensemble measurements made on muscle fibers with electron microscopy and spectroscopic experiments.
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Affiliation(s)
- Margot E Quinlan
- Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, 19104-6083, USA
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12
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Liu J, Reedy MC, Goldman YE, Franzini-Armstrong C, Sasaki H, Tregear RT, Lucaveche C, Winkler H, Baumann BAJ, Squire JM, Irving TC, Reedy MK, Taylor KA. Electron tomography of fast frozen, stretched rigor fibers reveals elastic distortions in the myosin crossbridges. J Struct Biol 2005; 147:268-82. [PMID: 15450296 DOI: 10.1016/j.jsb.2004.03.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 03/19/2004] [Indexed: 11/16/2022]
Abstract
As a first step toward freeze-trapping and 3-D modeling of the very rapid load-induced structural responses of active myosin heads, we explored the conformational range of longer lasting force-dependent changes in rigor crossbridges of insect flight muscle (IFM). Rigor IFM fibers were slam-frozen after ramp stretch (1000 ms) of 1-2% and freeze-substituted. Tomograms were calculated from tilt series of 30 nm longitudinal sections of Araldite-embedded fibers. Modified procedures of alignment and correspondence analysis grouped self-similar crossbridge forms into 16 class averages with 4.5 nm resolution, revealing actin protomers and myosin S2 segments of some crossbridges for the first time in muscle thin sections. Acto-S1 atomic models manually fitted to crossbridge density required a range of lever arm adjustments to match variably distorted rigor crossbridges. Some lever arms were unchanged compared with low tension rigor, while others were bent and displaced M-ward by up to 4.5 nm. The average displacement was 1.6 +/- 1.0 nm. "Map back" images that replaced each unaveraged 39 nm crossbridge motif by its class average showed an ordered mix of distorted and unaltered crossbridges distributed along the 116 nm repeat that reflects differences in rigor myosin head loading even before stretch.
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Affiliation(s)
- Jun Liu
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
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Gundapaneni D, Xu J, Root DD. High flexibility of the actomyosin crossbridge resides in skeletal muscle myosin subfragment-2 as demonstrated by a new single molecule assay. J Struct Biol 2005; 149:117-26. [PMID: 15681228 DOI: 10.1016/j.jsb.2004.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 10/20/2004] [Indexed: 10/26/2022]
Abstract
Popular views of force generation in muscle indicate that a lever arm in the myosin head initiates displacement of the thin filament. However, this lever arm is attached to the thick filament backbone by a flexible combination of coiled coils and hinges in the myosin subfragment-2 (S2); therefore, efficient force generation depends on tension development in this linking structure. Herein, a single molecule assay is developed to examine the flexibility of the intact S2 relative to that of the myosin head. Fluorescently labeled myosin rod is polymerized onto a single myosin molecule that is bound to actin, and the resulting Brownian motion of the rod is analyzed at video rates by digital image processing. Complete rotations of the rod suggest significant amounts of random coil in the linking structure. The close similarity of twist rates for double-headed and single-headed myosin indicates that most of the flexibility originates at or beyond the first pitch of coiled coil in S2 and most likely at the hinge connecting S2 and the light meromyosin. The myosin head has a smaller but still detectable impact on this flexibility, since the addition of ADP to the rigor crossbridge produces differential effects on the torsional characteristics of double-headed versus single-headed myosin.
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Affiliation(s)
- Deepika Gundapaneni
- Division of Biochemistry and Molecular Biology, Department of Biological Sciences, University of North Texas, PO Box 305220, Denton, TX 76203-5220, USA
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Tama F, Feig M, Liu J, Brooks CL, Taylor KA. The requirement for mechanical coupling between head and S2 domains in smooth muscle myosin ATPase regulation and its implications for dimeric motor function. J Mol Biol 2005; 345:837-54. [PMID: 15588830 DOI: 10.1016/j.jmb.2004.10.084] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 10/28/2004] [Accepted: 10/28/2004] [Indexed: 10/26/2022]
Abstract
A combination of experimental structural data, homology modelling and elastic network normal mode analysis is used to explore how coupled motions between the two myosin heads and the dimerization domain (S2) in smooth muscle myosin II determine the domain movements required to achieve the inhibited state of this ATP-dependent molecular motor. These physical models rationalize the empirical requirement for at least two heptads of non-coiled alpha-helix at the junction between the myosin heads and S2, and the dependence of regulation on S2 length. The results correlate well with biochemical data regarding altered conformational-dependent solubility and stability. Structural models of the conformational transition between putative active states and the inhibited state show that torsional flexibility of the S2 alpha-helices is a key mechanical requirement for myosin II regulation. These torsional motions of the myosin heads about their coiled coil alpha-helices affect the S2 domain structure, which reciprocally affects the motions of the myosin heads. This inter-relationship may explain a large body of data on function of molecular motors that form dimers through a coiled-coil domain.
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Affiliation(s)
- Florence Tama
- Department of Molecular Biology, TPC6, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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