Each of the heads of the motor protein myosin II is capable of supporting motion. A previous report showed that double-headed myosin generates twice the displacement of single-headed myosin (Tyska, M.J., D.E. Dupuis, W.H. Guilford, J.B. Patlak, G.S. Waller, K.M. Trybus, D.M. Warshaw, and S. Lowey. 1999. Proc. Natl. Acad. Sci. USA. 96:4402–4407). To determine the role of the second head, we expressed a smooth muscle heterodimeric heavy meromyosin (HMM) with one wild-type head, and the other locked in a weak actin-binding state by introducing a point mutation in switch II (E470A). Homodimeric E470A HMM did not support in vitro motility, and only slowly hydrolyzed MgATP. Optical trap measurements revealed that the heterodimer generated unitary displacements of 10.4 nm, strikingly similar to wild-type HMM (10.2 nm) and approximately twice that of single-headed subfragment-1 (4.4 nm). These data show that a double-headed molecule can achieve a working stroke of ∼10 nm with only one active head and an inactive weak-binding partner. We propose that the second head optimizes the orientation and/or stabilizes the structure of the motion-generating head, thereby resulting in maximum displacement.
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4 August 2003
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August 04 2003
A mutant heterodimeric myosin with one inactive head generates maximal displacement
Neil M. Kad,
Neil M. Kad
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Arthur S. Rovner,
Arthur S. Rovner
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Patricia M. Fagnant,
Patricia M. Fagnant
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Peteranne B. Joel,
Peteranne B. Joel
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Guy G. Kennedy,
Guy G. Kennedy
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Joseph B. Patlak,
Joseph B. Patlak
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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David M. Warshaw,
David M. Warshaw
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Kathleen M. Trybus
Kathleen M. Trybus
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
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Neil M. Kad
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Arthur S. Rovner
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Patricia M. Fagnant
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Peteranne B. Joel
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Guy G. Kennedy
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Joseph B. Patlak
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
David M. Warshaw
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Kathleen M. Trybus
Department of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405
Address correspondence to David M. Warshaw, Dept. of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405-0068. Tel.: (802) 656-2540. Fax: (802) 656-0747. email: [email protected]; or Kathleen M. Trybus, Dept. of Molecular Physiology and Biophysics, University of Vermont, Health Science Research Facility, Burlington, VT 05405-0068. Tel.: (802) 656-8750. Fax: (802) 656-0747. email: [email protected]
N.M. Kad and A.S. Rovner contributed equally to this paper.
Abbreviations used in this paper: FPLC, fast performance liquid chromatography; HMM, heavy meromyosin; Pyr-actin, pyrene-labeled actin; S1-neo, single-headed subfragment-1 with neonatal epitope tag; wt-HMM, wild-type heavy meromyosin.
Received:
April 04 2003
Accepted:
June 18 2003
Online ISSN: 1540-8140
Print ISSN: 0021-9525
The Rockefeller University Press
2003
J Cell Biol (2003) 162 (3): 481–488.
Article history
Received:
April 04 2003
Accepted:
June 18 2003
Citation
Neil M. Kad, Arthur S. Rovner, Patricia M. Fagnant, Peteranne B. Joel, Guy G. Kennedy, Joseph B. Patlak, David M. Warshaw, Kathleen M. Trybus; A mutant heterodimeric myosin with one inactive head generates maximal displacement . J Cell Biol 4 August 2003; 162 (3): 481–488. doi: https://doi.org/10.1083/jcb.200304023
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