A gel phase promotes condensation of liquid P granules in Caenorhabditis elegans embryos

Andrea Putnam, Madeline Cassani, Jarrett Smith, Geraldine Seydoux

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


RNA granules are subcellular compartments that are proposed to form by liquid–liquid phase separation (LLPS), a thermodynamic process that partitions molecules between dilute liquid phases and condensed liquid phases. The mechanisms that localize liquid phases in cells, however, are not fully understood. P granules are RNA granules that form in the posterior of Caenorhabditis elegans embryos. Theoretical studies have suggested that spontaneous LLPS of the RNA-binding protein PGL-3 with RNA drives the assembly of P granules. We find that the PGL-3 phase is intrinsically labile and requires a second phase for stabilization in embryos. The second phase is formed by gel-like assemblies of the disordered protein MEG-3 that associate with liquid PGL-3 droplets in the embryo posterior. Co-assembly of gel phases and liquid phases confers local stability and long-range dynamics, both of which contribute to localized assembly of P granules. Our findings suggest that condensation of RNA granules can be regulated spatially by gel-like polymers that stimulate LLPS locally in the cytoplasm.

Original languageEnglish (US)
Pages (from-to)220-226
Number of pages7
JournalNature Structural and Molecular Biology
Issue number3
StatePublished - Mar 1 2019

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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