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Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin

Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Previously, we found that Ena takes approximately...

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Autores principales: Harker, Alyssa J., Katkar, Harshwardhan H., Bidone, Tamara C., Aydin, Fikret, Voth, Gregory A., Applewhite, Derek A., Kovar, David R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589784/
https://www.ncbi.nlm.nih.gov/pubmed/30601697
http://dx.doi.org/10.1091/mbc.E18-08-0500
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author Harker, Alyssa J.
Katkar, Harshwardhan H.
Bidone, Tamara C.
Aydin, Fikret
Voth, Gregory A.
Applewhite, Derek A.
Kovar, David R.
author_facet Harker, Alyssa J.
Katkar, Harshwardhan H.
Bidone, Tamara C.
Aydin, Fikret
Voth, Gregory A.
Applewhite, Derek A.
Kovar, David R.
author_sort Harker, Alyssa J.
collection PubMed
description Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Previously, we found that Ena takes approximately threefold longer processive runs on trailing barbed ends of fascin-bundled F-actin. Here, we used single-molecule TIRFM (total internal reflection fluorescence microscopy) and developed a kinetic model to further dissect Ena/VASP’s processive mechanism on bundled filaments. We discovered that Ena’s enhanced processivity on trailing barbed ends is specific to fascin bundles, with no enhancement on fimbrin or α-actinin bundles. Notably, Ena/VASP’s processive run length increases with the number of both fascin-bundled filaments and Ena “arms,” revealing avidity facilitates enhanced processivity. Consistently, Ena tetramers form more filopodia than mutant dimer and trimers in Drosophila culture cells. Moreover, enhanced processivity on trailing barbed ends of fascin-bundled filaments is an evolutionarily conserved property of Ena/VASP homologues, including human VASP and Caenorhabditis elegans UNC-34. These results demonstrate that Ena tetramers are tailored for enhanced processivity on fascin bundles and that avidity of multiple arms associating with multiple filaments is critical for this process. Furthermore, we discovered a novel regulatory process whereby bundle size and bundling protein specificity control activities of a processive assembly factor.
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spelling pubmed-65897842019-07-02 Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin Harker, Alyssa J. Katkar, Harshwardhan H. Bidone, Tamara C. Aydin, Fikret Voth, Gregory A. Applewhite, Derek A. Kovar, David R. Mol Biol Cell Articles Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Previously, we found that Ena takes approximately threefold longer processive runs on trailing barbed ends of fascin-bundled F-actin. Here, we used single-molecule TIRFM (total internal reflection fluorescence microscopy) and developed a kinetic model to further dissect Ena/VASP’s processive mechanism on bundled filaments. We discovered that Ena’s enhanced processivity on trailing barbed ends is specific to fascin bundles, with no enhancement on fimbrin or α-actinin bundles. Notably, Ena/VASP’s processive run length increases with the number of both fascin-bundled filaments and Ena “arms,” revealing avidity facilitates enhanced processivity. Consistently, Ena tetramers form more filopodia than mutant dimer and trimers in Drosophila culture cells. Moreover, enhanced processivity on trailing barbed ends of fascin-bundled filaments is an evolutionarily conserved property of Ena/VASP homologues, including human VASP and Caenorhabditis elegans UNC-34. These results demonstrate that Ena tetramers are tailored for enhanced processivity on fascin bundles and that avidity of multiple arms associating with multiple filaments is critical for this process. Furthermore, we discovered a novel regulatory process whereby bundle size and bundling protein specificity control activities of a processive assembly factor. The American Society for Cell Biology 2019-03-21 /pmc/articles/PMC6589784/ /pubmed/30601697 http://dx.doi.org/10.1091/mbc.E18-08-0500 Text en © 2019 Harker 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
Harker, Alyssa J.
Katkar, Harshwardhan H.
Bidone, Tamara C.
Aydin, Fikret
Voth, Gregory A.
Applewhite, Derek A.
Kovar, David R.
Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
title Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
title_full Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
title_fullStr Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
title_full_unstemmed Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
title_short Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
title_sort ena/vasp processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589784/
https://www.ncbi.nlm.nih.gov/pubmed/30601697
http://dx.doi.org/10.1091/mbc.E18-08-0500
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