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Mechanism of Actin Bundle Assembly, Mechanics and Structure by Ion Interaction

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Date Issued:
2017
Abstract/Description:
The assembly of actin filaments into bundles plays an essential role in mechanical strength and dynamic reorganization of cytoskeleton. Divalent counterions at high concentrations promote bundle formation through electrostatic attraction between charged filaments. Although it has been hypothesized that specific cation interactions may contribute to salt-induced bundling, molecular mechanisms of how salt modulates bundle assembly and mechanics are not well established. Here we determine the mechanical and dynamic properties of actin bundles with physiologically relevant cations. Using total internal reflection fluorescence (TIRF) microscopy, we measure the bending stiffness of actin bundles determined by persistence length analysis. We characterize real-time formation of bundles by dynamic light scattering intensity and direct visualization using TIRF microscopy. Our results show that divalent cations modulate bundle stiffness as well as time-dependent average bundle size. Furthermore, molecular dynamic simulations propose specificity for cation binding on actin filaments to form bundles. The work suggests that cation interactions serve a regulatory function in bundle assembly dynamics, mechanics, and structure.
Title: Mechanism of Actin Bundle Assembly, Mechanics and Structure by Ion Interaction.
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Name(s): Castaneda, Nicholas, Author
Kang, Hyeran, Committee Chair
Huo, Qun, Committee Member
Gesquiere, Andre, Committee Member
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2017
Publisher: University of Central Florida
Language(s): English
Abstract/Description: The assembly of actin filaments into bundles plays an essential role in mechanical strength and dynamic reorganization of cytoskeleton. Divalent counterions at high concentrations promote bundle formation through electrostatic attraction between charged filaments. Although it has been hypothesized that specific cation interactions may contribute to salt-induced bundling, molecular mechanisms of how salt modulates bundle assembly and mechanics are not well established. Here we determine the mechanical and dynamic properties of actin bundles with physiologically relevant cations. Using total internal reflection fluorescence (TIRF) microscopy, we measure the bending stiffness of actin bundles determined by persistence length analysis. We characterize real-time formation of bundles by dynamic light scattering intensity and direct visualization using TIRF microscopy. Our results show that divalent cations modulate bundle stiffness as well as time-dependent average bundle size. Furthermore, molecular dynamic simulations propose specificity for cation binding on actin filaments to form bundles. The work suggests that cation interactions serve a regulatory function in bundle assembly dynamics, mechanics, and structure.
Identifier: CFE0006572 (IID), ucf:51307 (fedora)
Note(s): 2017-05-01
M.S.
Graduate Studies, Nanoscience Technology Center
Masters
This record was generated from author submitted information.
Subject(s): actin -- polyelectrolyte -- persistence length -- bundle-specific cation binding
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0006572
Restrictions on Access: campus 2018-05-15
Host Institution: UCF

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