Elucidating vimentin interaction with zinc ions and its interplay with oxidative modifications through crosslinking assays and molecular dynamics simulations

The intermediate filament protein vimentin is involved in essential cellular processes, including cell division and stress responses. Vimentin oxidative modifications impact network reorganization and its single cysteine residue, Cys328, acts as a redox sensor. Vimentin binds zinc, which influences its assembly by undefined mechanisms. Here, results from combined biochemical and molecular dynamics studies support that zinc ions interact with Cys328 in its thiolate form, whereas Glu329 and Asp331 stabilize zinc coordination. Vimentin oxidation can induce disulfide crosslinking, implying a close proximity of cysteine residues in certain vimentin associations, validated by our computational models. Notably, micromolar zinc concentrations selectively prevent Cys328 alkylation and crosslinking. These effects are not mimicked by magnesium, consistent with the fewer magnesium ions hosted at the cysteine region. Altogether, our results pinpoint the region surrounding Cys328, highly conserved in type III intermediate filaments, as a hot spot for zinc binding, which modulates Cys328 reactivity and vimentin assembly.