PT  - JOURNAL ARTICLE
AU  - Thomas J. Böddeker
AU  - Kathryn A. Rosowski
AU  - Doris Berchtold
AU  - Leonidas Emmanouilidis
AU  - Yaning Han
AU  - Frédéric H. T. Allain
AU  - Robert W. Style
AU  - Lucas Pelkmans
AU  - Eric R. Dufresne
TI  - Non-specific adhesive forces between filaments and membraneless organelles
AID  - 10.1101/2021.07.22.453380
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.07.22.453380
4099  - http://biorxiv.org/content/early/2021/07/23/2021.07.22.453380.short
4100  - http://biorxiv.org/content/early/2021/07/23/2021.07.22.453380.full
AB  - Membraneless organelles are liquid-like domains that form inside living cells by phase-separation. While standard physical models of their formation assume their surroundings to be a simple liquid, the cytoplasm is an active viscoelastic environment. To investigate potential coupling of phase separation with the cytoskeleton, we quantify structural correlations of stress granules and microtubules in a human-derived epithelial cell line. We find that microtubule networks are significantly perturbed in the vicinity of stress granules, and that large stress granules conform to the local pore-structure of the microtubule network. When microtubules are depolymerized by nocodazole, tubulin enrichment is localized near the surface of stress granules. We interpret these data using a thermodynamic model of partitioning of particles to the surface and bulk of droplets. This analysis shows that proteins generically have a non-specific affinity for droplet interfaces, which becomes most apparent when they weakly partition to the bulk of droplets and have a large molecular weight. In this framework, our data is consistent with a weak (≲ kbT) affinity of tubulin sub-units for stress granule interfaces. As microtubules polymerize their affinity for interfaces increases, providing sufficient adhesion to deform droplets and/or the network. We validate this basic physical phenomena in vitro through the interaction of a simple protein-RNA condensate with tubulin and microtubules.Competing Interest StatementThe authors have declared no competing interest.