EMD-51424
Tomogram of pyrenoid of T. pseudonana Shell4 knock-out
EMD-51424
Tomography
Map released: 09/10/2024
Last modified: 30/10/2024
Sample Organism:
T. pseudonana
Sample: T. pseudonana shell4 KO
Deposition Authors: Demulder M, Engel B
Sample: T. pseudonana shell4 KO
Deposition Authors: Demulder M, Engel B
A protein blueprint of the diatom CO 2 -fixing organelle.
Nam O,
Musial S,
Demulder M,
McKenzie C,
Dowle A,
Dowson M,
Barrett J,
Blaza JN,
Engel BD
,
Mackinder LCM
(2024) Cell , 187 , 5935 - 5950.e18
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(2024) Cell , 187 , 5935 - 5950.e18
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.
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.