1. Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments
- Author
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Rizal F. Hariadi, Shirley Sutton, Arjun S. Adhikari, James A. Spudich, Ruth F. Sommese, Rebecca E. Taylor, and Sivaraj Sivaramakrishnan
- Subjects
Force generation ,Materials science ,Movement ,Biomedical Engineering ,Motility ,Bioengineering ,Nanotechnology ,macromolecular substances ,Myosins ,Microfilament ,Models, Biological ,Sarcomere ,Myosin head ,Myosin ,Humans ,General Materials Science ,A-DNA ,Electrical and Electronic Engineering ,Actin ,Nanotubes ,DNA ,Condensed Matter Physics ,Actins ,Atomic and Molecular Physics, and Optics ,Biophysics - Abstract
The sarcomere of muscle is composed of tens of thousands of myosin motors that self-assemble into thick filaments and interact with surrounding actin-based thin filaments in a dense, near-crystalline hexagonal lattice. Together, these actin-myosin interactions enable large-scale movement and force generation, two primary attributes of muscle. Research on isolated fibres has provided considerable insight into the collective properties of muscle, but how actin-myosin interactions are coordinated in an ensemble remains poorly understood. Here, we show that artificial myosin filaments, engineered using a DNA nanotube scaffold, provide precise control over motor number, type and spacing. Using both dimeric myosin V- and myosin VI-labelled nanotubes, we find that neither myosin density nor spacing has a significant effect on the gliding speed of actin filaments. This observation supports a simple model of myosin ensembles as energy reservoirs that buffer individual stochastic events to bring about smooth, continuous motion. Furthermore, gliding speed increases with cross-bridge compliance, but is limited by Brownian effects. As a first step to reconstituting muscle motility, we demonstrate human β-cardiac myosin-driven gliding of actin filaments on DNA nanotubes.
- Published
- 2015
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