A protein blueprint of the diatom CO2-fixing organelle

Onyou Nam, Sabina Musiał, Manon Demulder, Caroline McKenzie, Adam Dowle, Matthew Dowson, James Barrett, James N Blaza, Benjamin D Engel, Luke C M Mackinder

Research output: Contribution to journalArticlepeer-review

Abstract

Diatoms are central to the global carbon cycle. At the heart of diatom carbon fixation is an overlooked organelle called the pyrenoid, where concentrated CO2 is delivered to densely packed Rubisco. Diatom pyrenoids fix approximately one-fifth of global CO2, but the protein composition of this organelle is largely unknown. Using fluorescence protein tagging and affinity purification-mass spectrometry, we generate a high-confidence spatially defined protein-protein interaction network for the diatom pyrenoid. Within our pyrenoid interaction network are 10 proteins with previously unknown functions. We show that six of these form a shell that encapsulates the Rubisco matrix and is critical for pyrenoid structural integrity, shape, and function. Although not conserved at a sequence or structural level, the diatom pyrenoid shares some architectural similarities to prokaryotic carboxysomes. Collectively, our results support the convergent evolution of pyrenoids across the two main plastid lineages and uncover a major structural and functional component of global CO2 fixation.

Original languageEnglish
Pages (from-to)5935-5950.e18
Number of pages16
JournalCell
Volume187
Issue number21
Early online date4 Oct 2024
DOIs
Publication statusPublished - 17 Oct 2024

Bibliographical note

© 2024 The Author(s)

Keywords

  • Diatoms/metabolism
  • Carbon Dioxide/metabolism
  • Organelles/metabolism
  • Ribulose-Bisphosphate Carboxylase/metabolism
  • Carbon Cycle
  • Protein Interaction Maps
  • Photosynthesis

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