Zinc Differentially Modulates the Assembly of Soluble and Polymerized Vimentin

Abstract

The intermediate filament protein vimentin constitutes a critical sensor for electrophilic and oxidative stress. We previously showed that vimentin interacts with zinc, which affects its assembly and redox sensing. Here, we used vimentin wt and C328S, an oxidation-resistant mutant showing improved NaCl-induced polymerization, to assess the impact of zinc on soluble and polymerized vimentin by light scattering and electron microscopy. Zinc acts as a switch, reversibly inducing the formation of vimentin oligomeric species. High zinc concentrations elicit optically-detectable vimentin structures with a characteristic morphology depending on the support. These effects also occur in vimentin C328S, but are not mimicked by magnesium. Treatment of vimentin with micromolar ZnCl2 induces fibril-like particles that do not assemble into filaments, but form aggregates upon subsequent addition of NaCl. In contrast, when added to NaCl-polymerized vimentin, zinc increases the diameter or induces lateral association of vimentin wt filaments. Remarkably, these effects are absent or attenuated in vimentin C328S filaments. Therefore, the zinc-vimentin interaction depends on the chemical environment and on the assembly state of the protein, leading to atypical polymerization of soluble vimentin, likely through electrostatic interactions, or to broadening and lateral association of preformed filaments through mechanisms requiring the cysteine residue. Thus, the impact of zinc on vimentin assembly and redox regulation is envisaged.

Vimentin as a Multifaceted Player and Potential Therapeutic Target in Viral Infections

“…In principle, agents known to alter vimentin structure, such as simvastatin or cyclopentenone prostaglandins, could potentially affect extracellular vimentin. In addition, availability of divalent cations, including Ca 2+ , Mg 2+ and Zn 2+ [6,202,203], can affect the state of vimentin oligomerization and its mechanical properties. However, whether they affect extracellular vimentin has not been studied.…”

Polyelectrolyte Gels Formed by Filamentous Biopolymers: Dependence of Crosslinking Efficiency on the Chemical Softness of Divalent Cations

“…There are however some exceptions. For example, zinc and copper are significantly more efficient in bundling VIFs than Pf1 virus, and this might reflect the reports that Zn 2+ can interact with the sulfhydryl group of vimentin [ 17 , 18 ], an amino acid that Pf1 virus lacks and that can also bind Cu 2+ . Indeed copper and zinc have been used to form crosslinked networks of VIFs that increase their elastic modulus well above the levels possible with other divalent cations [ 19 ].…”

Molecular Insight into the Regulation of Vimentin by Cysteine Modifications and Zinc Binding

“…This feature promotes its interaction with divalent cations, such as calcium and magnesium, which, at millimolar levels, influence vimentin in vitro assembly and have been reported to behave as crosslinkers for certain regions of the protein [42,43], affecting the properties of the network [44]. In recent works, we observed that zinc availability influenced the organization of the vimentin network and its resistance to oxidants in cells [9,10] and that micromolar zinc concentrations modulated vimentin in vitro assembly [45]. Thus, we proposed that zinc could interact with vimentin at several sites, of which the region surrounding Cys328 could be especially relevant [46].…”

“…Thus, these results support the interaction of zinc with vimentin in the proximity of the cysteine residue. Nevertheless, the possibility that zinc could induce vimentin aggregation and/or conformational changes, reducing the accessibility of Cys328 to modification, should also be considered [45]. In contrast, we have previously reported that NaCl-induced polymerization does not preclude vimentin oxidation or lipoxidation, which indicates that the protection is not merely due to lower cysteine accessibility in oligomeric structures and suggests a distinct role for zinc [10].…”