Molecular basis of the mechanical hierarchy in myomesin dimers for sarcomere integrity
Myomesin is one of the most important structural molecules constructing the M-band in the force-generating unit of striated muscle, and a critical structural maintainer of the sarcomere. Using molecular dynamics simulations, we here dissect the mechanical properties of the structurally known buildin...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
19 August 2014
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| In: |
Biophysical journal
Year: 2014, Volume: 107, Issue: 4, Pages: 965-973 |
| ISSN: | 1542-0086 |
| DOI: | 10.1016/j.bpj.2014.06.043 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1016/j.bpj.2014.06.043 Verlag, lizenzpflichtig, Volltext: http://www.sciencedirect.com/science/article/pii/S0006349514006894 
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| Author Notes: | Senbo Xiao and Frauke Gräter |
| Summary: | Myomesin is one of the most important structural molecules constructing the M-band in the force-generating unit of striated muscle, and a critical structural maintainer of the sarcomere. Using molecular dynamics simulations, we here dissect the mechanical properties of the structurally known building blocks of myomesin, namely α-helices, immunglobulin (Ig) domains, and the dimer interface at myomesin’s 13th Ig domain, covering the mechanically important C-terminal part of the molecule. We find the interdomain α-helices to be stabilized by the hydrophobic interface formed between the N-terminal half of these helices and adjacent Ig domains, and, interestingly, to show a rapid unfolding and refolding equilibrium especially under low axial forces up to ∼15 pN. These results support and yield atomic details for the notion of recent atomic-force microscopy experiments, namely, that the unique helices inserted between Ig domains in myomesin function as elastomers and force buffers. Our results also explain how the C-terminal dimer of two myomesin molecules is mechanically outperforming the helices and Ig domains in myomesin and elsewhere, explaining former experimental findings. This study provides a fresh view onto how myomesin integrates elastic helices, rigid immunoglobulin domains, and an extraordinarily resistant dimer into a molecular structure, to feature a mechanical hierarchy that represents a firm and yet extensible molecular anchor to guard the stability of the sarcomere. |
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| Item Description: | Gesehen am 29.07.2020 |
| Physical Description: | Online Resource |
| ISSN: | 1542-0086 |
| DOI: | 10.1016/j.bpj.2014.06.043 |