Effect of Divalent Cations on the Structure and Mechanics of Vimentin Intermediate Filaments

Wu, Huayin; Shen, Yinan; Wang, Dianzhuo; Herrmann, Harald; Goldman, Robert D.; Weitz, David A.

doi:10.1016/j.bpj.2020.05.016

Cited by 23 publications

(45 citation statements)

References 48 publications

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“…Interestingly, we observe a difference between the two divalent ions, CaCl 2 and MgCl 2 , regarding the concentration needed for precipitation, supporting earlier reports. 18,20 This phenomenon can be explained by the Hofmeister effect that puts cations in an order according to their ability to precipitate proteins. [43][44][45][46] Looking at the Hofmeister series for the ions used here, we obtain K + 4 Na + 4 Mg 2+ 4 Ca 2+ , matching our findings.…”

Section: Discussionmentioning

confidence: 99%

“…This result is in agreement with previously published work. 20,40,41 Fluorescence microscopy provides an overview of the propensity of vimentin filaments to form bundles or networks in the presence of different types of ions. The method cannot, however, shed light on the structure of the filaments formed.…”

Section: Vimentin Filament Assembly Using Different Ion Typesmentioning

confidence: 99%

“…18 Vimentin filaments assembled in the presence of ZnCl 2 bundle at lower ion concentrations compared to the addition of CaCl 2 . 20 Although these studies provide evidence that ion concentration, valency and type strongly influence vimentin assembly, systematic data are largely missing. Here, we investigate the influence of cations on the assembly of vimentin in a systematic way by combining fluorescence microscopy and SAXS.…”

Section: Introductionmentioning

confidence: 99%

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Ion type and valency differentially drive vimentin tetramers into intermediate filaments or higher order assemblies

et al. 2021

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Section: Discussionmentioning

confidence: 99%

Section: Vimentin Filament Assembly Using Different Ion Typesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ion type and valency differentially drive vimentin tetramers into intermediate filaments or higher order assemblies

et al. 2021

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“…Removing the cystein from the rod domain of the protein enables smooth assembly even after labeling. As we did not add zinc ions in our experiments, 37 the missing cystein is not expected to influence the assembly and architecture of the filaments. Indeed, it has been shown that vimentin C328A assembles in the same way as wildtype vimentin.…”

Section: Methodsmentioning

confidence: 93%

Post-Translational Modifications Soften Vimentin Intermediate Filaments

Kraxner

Lorenz

Menzel

et al. 2020

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The mechanical properties of biological cells are determined by the cytoskeleton, a composite biopolymer network consisting of microtubules, actin filaments and intermediate filaments (IFs). By differential expression of the cytoskeletal proteins, modulation of the network architecture and the interactions between the filaments, cell mechanics may be adapted to varying requirements on the cell. Here, we focus on the intermediate filament protein vimentin and introduce post-translational modifications as an additional, much faster mechanism for mechanical modulation. We study the impact of phosphorylation on filament mechanics by recording precise force-strain curves using optical traps. Whereas full phosphorylation leads to disassembly of IFs, partial phosphorylation results in softening of the filaments. We show that binding of the protein 14-3-3 to phosphorylated vimentin IFs further enhances this effect and speculate that in the cell 14-3-3 may serve to preserve the softening and thereby the altered cell mechanics. By employing phosphomimetic mutants and complementary Monte Carlo simulations, we explain our observation through the additional charges introduced during.The cytoskeleton of eukaryotes consists of three filament systems -microtubules, actin filaments and intermediate filaments (IFs) -which form a complex biopolymer network. The exact composition of the cytoskeleton and the interplay between the three filament types are of great importance as they define the mechanical properties of different cell types. 1Microtubules and actin filaments are highly conserved throughout cell types and between organisms, whereas more than 70 human genes encode for IFs. 2 Although different IFs are expressed in a cell type specific manner, they all share the same hierarchical assembly pathway from monomers to filaments. The secondary structure of the monomers consists of an α-helical rod domain, flanked by intrinsically disordered head and tail domains. 3,4 During assembly, two monomers align and form parallel coiled-coil dimers, two dimers form antiparallel, half-staggered tetramers, and multiple tetramers constitute a unit-length filament (ULF) (see Fig. 1a). Subsequent longitudinal annealing yields elongated filaments with a diameter of about 10 nm. 5 This hierarchical structure of IFs, in contrast to polar microtubules or actin filaments that elongate by rapid growth at the plus-end, grants IFs their unique mechanical properties. [6][7][8] Here, we study the most abundant IF, vimentin, which is found in cells of mesenchymal origin. 5,9 Single vimentin filaments are highly extensible and can be elongated up to at least 4.5 fold. 7,10,11 During elongation, three regimes are observed in the force-strain curves: an initial linear (elastic) increase, a plateau region and a subsequent stiffening. 6,7,12,13 These

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“…Removing the cystein from the rod domain of the protein enables smooth assembly even after labeling. As we did not add zinc ions in our experiments 28 , the missing cystein is not expected to influence the assembly and architecture of the filaments. Indeed, it has been shown that vimentin C328A assembles in the same way as wildtype vimentin 29 .…”

Section: Vimentin Purificationmentioning

confidence: 92%