Interplay of self-organization of microtubule asters and crosslinking protein condensates

Sumon Sahu, Prashali Chauhan, Ellie Lumen, Kelsey Moody, Karthik Peddireddy, Nandini Mani, Radhika Subramanian, Rae Robertson-Anderson, Aaron J. Wolfe, Jennifer L. Ross

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The cytoskeleton is a major focus of physical studies to understand organization inside cells given its primary role in cell motility, cell division, and cell mechanics. Recently, protein condensation has been shown to be another major intracellular organizational strategy. Here, we report that the microtubule crosslinking proteins, MAP65-1 and PRC1, can form phase separated condensates at physiological salt and temperature without additional crowding agents in vitro. The size of the droplets depends on the concentration of protein. MAP65 condensates are liquid at first and can gelate over time. We show that these condensates can nucleate and grow microtubule bundles that form asters, regardless of the viscoelasticity of the condensate. The droplet size directly controls the number of projections in the microtubule asters, demonstrating that the MAP65 concentration can control the organization of microtubules. When gel-like droplets nucleate and grow asters from a shell of tubulin at the surface, the microtubules are able to refluidize the MAP65 condensate, returning the MAP65 molecules to solution. This work implies that there is an interplay between condensate formation from microtubule-associated proteins, microtubule organization, and condensate dissolution that could be important for the dynamics of intracellular organization.

Original languageEnglish (US)
Article numberpgad231
JournalPNAS Nexus
Volume2
Issue number7
DOIs
StatePublished - Jul 1 2023

Keywords

  • MAP65-1
  • aging
  • liquid-liquid phase separation
  • microtubule asters
  • self-organization

ASJC Scopus subject areas

  • General

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