The Eukaryotic CO2-Concentrating Organelle Is Liquid-like and Exhibits Dynamic Reorganization

Elizabeth S Freeman Rosenzweig, B. Xu, Luis Kuhn Cuellar, Antonio Martinez-Sanchez, Miroslava Schaffer, Mike Strauss, Heather N Cartwright, Pierre Ronceray, Jürgen M Plitzko, Friedrich Förster, Ned S Wingreen, Benjamin D Engel*, Luke C M Mackinder, Martin C Jonikas*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Approximately 30%-40% of global CO2 fixation occurs inside a non-membrane-bound organelle called the pyrenoid, which is found within the chloroplasts of most eukaryotic algae. The pyrenoid matrix is densely packed with the CO2-fixing enzyme Rubisco and is thought to be a crystalline or amorphous solid. Here, we show that the pyrenoid matrix of the unicellular alga Chlamydomonas reinhardtii is not crystalline but behaves as a liquid that dissolves and condenses during cell division. Furthermore, we show that new pyrenoids are formed both by fission and de novo assembly. Our modeling predicts the existence of a "magic number" effect associated with special, highly stable heterocomplexes that influences phase separation in liquid-like organelles. This view of the pyrenoid matrix as a phase-separated compartment provides a paradigm for understanding its structure, biogenesis, and regulation. More broadly, our findings expand our understanding of the principles that govern the architecture and inheritance of liquid-like organelles.

Original languageEnglish
Pages (from-to)148-162.e19
JournalCell
Volume171
Issue number1
DOIs
Publication statusPublished - 21 Sept 2017

Keywords

  • Algal Proteins
  • Carbon Dioxide
  • Chlamydomonas reinhardtii
  • Chloroplasts
  • Cryoelectron Microscopy
  • Organelle Biogenesis
  • Ribulose-Bisphosphate Carboxylase

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