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Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution
Tropomyosins regulate the dynamics and functions of the actin cytoskeleton by forming long chains along the two strands of actin filaments that act as gatekeepers for the binding of other actin-binding proteins. The fundamental molecular interactions underlying the binding of tropomyosin to actin ar...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The American Society for Cell Biology
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7851853/ https://www.ncbi.nlm.nih.gov/pubmed/32845787 http://dx.doi.org/10.1091/mbc.E19-10-0586 |
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author | Bareja, Ilina Wioland, Hugo Janco, Miro Nicovich, Philip R. Jégou, Antoine Romet-Lemonne, Guillaume Walsh, James Böcking, Till |
author_facet | Bareja, Ilina Wioland, Hugo Janco, Miro Nicovich, Philip R. Jégou, Antoine Romet-Lemonne, Guillaume Walsh, James Böcking, Till |
author_sort | Bareja, Ilina |
collection | PubMed |
description | Tropomyosins regulate the dynamics and functions of the actin cytoskeleton by forming long chains along the two strands of actin filaments that act as gatekeepers for the binding of other actin-binding proteins. The fundamental molecular interactions underlying the binding of tropomyosin to actin are still poorly understood. Using microfluidics and fluorescence microscopy, we observed the binding of the fluorescently labeled tropomyosin isoform Tpm1.8 to unlabeled actin filaments in real time. This approach, in conjunction with mathematical modeling, enabled us to quantify the nucleation, assembly, and disassembly kinetics of Tpm1.8 on single filaments and at the single-molecule level. Our analysis suggests that Tpm1.8 decorates the two strands of the actin filament independently. Nucleation of a growing tropomyosin domain proceeds with high probability as soon as the first Tpm1.8 molecule is stabilized by the addition of a second molecule, ultimately leading to full decoration of the actin filament. In addition, Tpm1.8 domains are asymmetrical, with enhanced dynamics at the edge oriented toward the barbed end of the actin filament. The complete description of Tpm1.8 kinetics on actin filaments presented here provides molecular insight into actin–tropomyosin filament formation and the role of tropomyosins in regulating actin filament dynamics. |
format | Online Article Text |
id | pubmed-7851853 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | The American Society for Cell Biology |
record_format | MEDLINE/PubMed |
spelling | pubmed-78518532021-02-10 Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution Bareja, Ilina Wioland, Hugo Janco, Miro Nicovich, Philip R. Jégou, Antoine Romet-Lemonne, Guillaume Walsh, James Böcking, Till Mol Biol Cell Articles Tropomyosins regulate the dynamics and functions of the actin cytoskeleton by forming long chains along the two strands of actin filaments that act as gatekeepers for the binding of other actin-binding proteins. The fundamental molecular interactions underlying the binding of tropomyosin to actin are still poorly understood. Using microfluidics and fluorescence microscopy, we observed the binding of the fluorescently labeled tropomyosin isoform Tpm1.8 to unlabeled actin filaments in real time. This approach, in conjunction with mathematical modeling, enabled us to quantify the nucleation, assembly, and disassembly kinetics of Tpm1.8 on single filaments and at the single-molecule level. Our analysis suggests that Tpm1.8 decorates the two strands of the actin filament independently. Nucleation of a growing tropomyosin domain proceeds with high probability as soon as the first Tpm1.8 molecule is stabilized by the addition of a second molecule, ultimately leading to full decoration of the actin filament. In addition, Tpm1.8 domains are asymmetrical, with enhanced dynamics at the edge oriented toward the barbed end of the actin filament. The complete description of Tpm1.8 kinetics on actin filaments presented here provides molecular insight into actin–tropomyosin filament formation and the role of tropomyosins in regulating actin filament dynamics. The American Society for Cell Biology 2020-10-15 /pmc/articles/PMC7851853/ /pubmed/32845787 http://dx.doi.org/10.1091/mbc.E19-10-0586 Text en © 2020 Bareja et al. “ASCB®,” “The American Society for Cell Biology®,” and “Molecular Biology of the Cell®” are registered trademarks of The American Society for Cell Biology. http://creativecommons.org/licenses/by-nc-sa/3.0 This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License. |
spellingShingle | Articles Bareja, Ilina Wioland, Hugo Janco, Miro Nicovich, Philip R. Jégou, Antoine Romet-Lemonne, Guillaume Walsh, James Böcking, Till Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution |
title | Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution |
title_full | Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution |
title_fullStr | Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution |
title_full_unstemmed | Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution |
title_short | Dynamics of Tpm1.8 domains on actin filaments with single-molecule resolution |
title_sort | dynamics of tpm1.8 domains on actin filaments with single-molecule resolution |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7851853/ https://www.ncbi.nlm.nih.gov/pubmed/32845787 http://dx.doi.org/10.1091/mbc.E19-10-0586 |
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