Assembly of the algal CO-fixing organelle, the pyrenoid, is guided by a Rubisco-binding motif.

TitleAssembly of the algal CO-fixing organelle, the pyrenoid, is guided by a Rubisco-binding motif.
Publication TypeJournal Article
Year of Publication2020
AuthorsMeyer, MT, Itakura, AK, Patena, W, Wang, L, He, S, Emrich-Mills, T, Lau, CS, Yates, G, Mackinder, LCM, Jonikas, MC
JournalSci Adv
Volume6
Issue46
Date Published2020 Nov
ISSN2375-2548
Abstract

<p>Approximately one-third of the Earth's photosynthetic CO assimilation occurs in a pyrenoid, an organelle containing the CO-fixing enzyme Rubisco. How constituent proteins are recruited to the pyrenoid and how the organelle's subcompartments-membrane tubules, a surrounding phase-separated Rubisco matrix, and a peripheral starch sheath-are held together is unknown. Using the model alga , we found that pyrenoid proteins share a sequence motif. We show that the motif is necessary and sufficient to target proteins to the pyrenoid and that the motif binds to Rubisco, suggesting a mechanism for targeting. The presence of the Rubisco-binding motif on proteins that localize to the tubules and on proteins that localize to the matrix-starch sheath interface suggests that the motif holds the pyrenoid's three subcompartments together. Our findings advance our understanding of pyrenoid biogenesis and illustrate how a single protein motif can underlie the architecture of a complex multilayered phase-separated organelle.</p>

DOI10.1126/sciadv.abd2408
Alternate JournalSci Adv
Full Text

Approximately one-third of the Earth's photosynthetic CO2 assimilation occurs in a pyrenoid, an organelle containing the CO2-fixing enzyme Rubisco. How constituent proteins are recruited to the pyrenoid and how the organelle's subcompartments-membrane tubules, a surrounding phase-separated Rubisco matrix, and a peripheral starch sheath-are held together is unknown. Using the model alga Chlamydomonas reinhardtii, we found that pyrenoid proteins share a sequence motif. We show that the motif is necessary and sufficient to target proteins to the pyrenoid and that the motif binds to Rubisco, suggesting a mechanism for targeting. The presence of the Rubisco-binding motif on proteins that localize to the tubules and on proteins that localize to the matrix-starch sheath interface suggests that the motif holds the pyrenoid's three subcompartments together. Our findings advance our understanding of pyrenoid biogenesis and illustrate how a single protein motif can underlie the architecture of a complex multilayered phase-separated organelle.

PubMed ID33177094
PubMed Central IDPMC7673724
Grant ListDP2 GM119137 / GM / NIGMS NIH HHS / United States