Mapping Local and Global Liquid Phase Behavior in Living Cells Using Photo-Oligomerizable Seeds

Cell. 2018 Nov 29;175(6):1467-1480.e13. doi: 10.1016/j.cell.2018.10.048.


Liquid-liquid phase separation plays a key role in the assembly of diverse intracellular structures. However, the biophysical principles by which phase separation can be precisely localized within subregions of the cell are still largely unclear, particularly for low-abundance proteins. Here, we introduce an oligomerizing biomimetic system, "Corelets," and utilize its rapid and quantitative light-controlled tunability to map full intracellular phase diagrams, which dictate the concentrations at which phase separation occurs and the transition mechanism, in a protein sequence dependent manner. Surprisingly, both experiments and simulations show that while intracellular concentrations may be insufficient for global phase separation, sequestering protein ligands to slowly diffusing nucleation centers can move the cell into a different region of the phase diagram, resulting in localized phase separation. This diffusive capture mechanism liberates the cell from the constraints of global protein abundance and is likely exploited to pattern condensates associated with diverse biological processes. VIDEO ABSTRACT.

Keywords: binodal; condensation; liquid-liquid phase separation; membraneless organelles; multivalent interactions; oligomerization; optogenetics; phase diagram; protein disorder; spinodal decomposition.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Video-Audio Media

MeSH terms

  • Animals
  • Biomimetic Materials* / pharmacokinetics
  • Biomimetic Materials* / pharmacology
  • Cytoplasm / metabolism*
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mice
  • Microscopy, Fluorescence / methods
  • NIH 3T3 Cells