Mechanistic dissection of increased enzymatic rate in a phase-separated compartment

William Peeples, Michael K. Rosen

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


Biomolecular condensates concentrate macromolecules into discrete cellular foci without an encapsulating membrane. Condensates are often presumed to increase enzymatic reaction rates through increased concentrations of enzymes and substrates (mass action), although this idea has not been widely tested and other mechanisms of modulation are possible. Here we describe a synthetic system where the SUMOylation enzyme cascade is recruited into engineered condensates generated by liquid–liquid phase separation of multidomain scaffolding proteins. SUMOylation rates can be increased up to 36-fold in these droplets compared to the surrounding bulk, depending on substrate KM. This dependency produces substantial specificity among different substrates. Analyses of reactions above and below the phase-separation threshold lead to a quantitative model in which reactions in condensates are accelerated by mass action and changes in substrate KM, probaby due to scaffold-induced molecular organization. Thus, condensates can modulate reaction rates both by concentrating molecules and physically organizing them. [Figure not available: see fulltext.].

Original languageEnglish (US)
Pages (from-to)693-702
Number of pages10
JournalNature chemical biology
Issue number6
StatePublished - Jun 2021

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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