Vimentin filaments integrate low-complexity domains in a complex helical structure
Matthias Eibauer, Miriam S. Weber, Rafael Kronenberg‐Tenga, Charlie T. Beales, Rajaa Boujemaa‐Paterski, Yagmur Turgay, Suganya Sivagurunathan, Julia Kraxner, Sarah Köster, Robert D. Goldman, Ohad Medalia
Abstract
Intermediate filaments (IFs) are integral components of the cytoskeleton. They provide cells with tissue-specific mechanical properties and are involved in numerous cellular processes. Due to their intricate architecture, a 3D structure of IFs has remained elusive. Here we use cryo-focused ion-beam milling, cryo-electron microscopy and tomography to obtain a 3D structure of vimentin IFs (VIFs). VIFs assemble into a modular, intertwined and flexible helical structure of 40 α-helices in cross-section, organized into five protofibrils. Surprisingly, the intrinsically disordered head domains form a fiber in the lumen of VIFs, while the intrinsically disordered tails form lateral connections between the protofibrils. Our findings demonstrate how protein domains of low sequence complexity can complement well-folded protein domains to construct a biopolymer with striking mechanical strength and stretchability.