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Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis

The concept of critical concentration (CC) is central to understanding the behavior of microtubules (MTs) and other cytoskeletal polymers. Traditionally, these polymers are understood to have one CC, measured in multiple ways and assumed to be the subunit concentration necessary for polymer assembly...

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Autores principales: Jonasson, Erin M., Mauro, Ava J., Li, Chunlei, Labuz, Ellen C., Mahserejian, Shant M., Scripture, Jared P., Gregoretti, Ivan V., Alber, Mark, Goodson, Holly V.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The American Society for Cell Biology 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7202068/
https://www.ncbi.nlm.nih.gov/pubmed/31577530
http://dx.doi.org/10.1091/mbc.E19-02-0101
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author Jonasson, Erin M.
Mauro, Ava J.
Li, Chunlei
Labuz, Ellen C.
Mahserejian, Shant M.
Scripture, Jared P.
Gregoretti, Ivan V.
Alber, Mark
Goodson, Holly V.
author_facet Jonasson, Erin M.
Mauro, Ava J.
Li, Chunlei
Labuz, Ellen C.
Mahserejian, Shant M.
Scripture, Jared P.
Gregoretti, Ivan V.
Alber, Mark
Goodson, Holly V.
author_sort Jonasson, Erin M.
collection PubMed
description The concept of critical concentration (CC) is central to understanding the behavior of microtubules (MTs) and other cytoskeletal polymers. Traditionally, these polymers are understood to have one CC, measured in multiple ways and assumed to be the subunit concentration necessary for polymer assembly. However, this framework does not incorporate dynamic instability (DI), and there is work indicating that MTs have two CCs. We use our previously established simulations to confirm that MTs have (at least) two experimentally relevant CCs and to clarify the behavior of individuals and populations relative to the CCs. At free subunit concentrations above the lower CC (CC(Elongation)), growth phases of individual filaments can occur transiently; above the higher CC (CC(NetAssembly)), the population’s polymer mass will increase persistently. Our results demonstrate that most experimental CC measurements correspond to CC(NetAssembly), meaning that “typical” DI occurs below the concentration traditionally considered necessary for polymer assembly. We report that [free tubulin] at steady state does not equal CC(NetAssembly), but instead approaches CC(NetAssembly) asymptotically as [total tubulin] increases, and depends on the number of stable MT nucleation sites. We show that the degree of separation between CC(Elongation) and CC(NetAssembly) depends on the rate of nucleotide hydrolysis. This clarified framework helps explain and unify many experimental observations.
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spelling pubmed-72020682020-06-06 Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis Jonasson, Erin M. Mauro, Ava J. Li, Chunlei Labuz, Ellen C. Mahserejian, Shant M. Scripture, Jared P. Gregoretti, Ivan V. Alber, Mark Goodson, Holly V. Mol Biol Cell Articles The concept of critical concentration (CC) is central to understanding the behavior of microtubules (MTs) and other cytoskeletal polymers. Traditionally, these polymers are understood to have one CC, measured in multiple ways and assumed to be the subunit concentration necessary for polymer assembly. However, this framework does not incorporate dynamic instability (DI), and there is work indicating that MTs have two CCs. We use our previously established simulations to confirm that MTs have (at least) two experimentally relevant CCs and to clarify the behavior of individuals and populations relative to the CCs. At free subunit concentrations above the lower CC (CC(Elongation)), growth phases of individual filaments can occur transiently; above the higher CC (CC(NetAssembly)), the population’s polymer mass will increase persistently. Our results demonstrate that most experimental CC measurements correspond to CC(NetAssembly), meaning that “typical” DI occurs below the concentration traditionally considered necessary for polymer assembly. We report that [free tubulin] at steady state does not equal CC(NetAssembly), but instead approaches CC(NetAssembly) asymptotically as [total tubulin] increases, and depends on the number of stable MT nucleation sites. We show that the degree of separation between CC(Elongation) and CC(NetAssembly) depends on the rate of nucleotide hydrolysis. This clarified framework helps explain and unify many experimental observations. The American Society for Cell Biology 2020-03-19 /pmc/articles/PMC7202068/ /pubmed/31577530 http://dx.doi.org/10.1091/mbc.E19-02-0101 Text en © 2020 Jonasson, Mauro, 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
Jonasson, Erin M.
Mauro, Ava J.
Li, Chunlei
Labuz, Ellen C.
Mahserejian, Shant M.
Scripture, Jared P.
Gregoretti, Ivan V.
Alber, Mark
Goodson, Holly V.
Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
title Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
title_full Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
title_fullStr Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
title_full_unstemmed Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
title_short Behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
title_sort behaviors of individual microtubules and microtubule populations relative to critical concentrations: dynamic instability occurs when critical concentrations are driven apart by nucleotide hydrolysis
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7202068/
https://www.ncbi.nlm.nih.gov/pubmed/31577530
http://dx.doi.org/10.1091/mbc.E19-02-0101
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