A Spatial Interactome Reveals the Protein Organization of the Algal CO2-Concentrating Mechanism.

TitleA Spatial Interactome Reveals the Protein Organization of the Algal CO2-Concentrating Mechanism.
Publication TypeJournal Article
Year of Publication2017
AuthorsMackinder, LCM, Chen, C, Leib, RD, Patena, W, Blum, SR, Rodman, M, Ramundo, S, Adams, CM, Jonikas, MC
JournalCell
Volume171
Issue1
Pagination133-147.e14
Date Published2017 Sep 21
ISSN1097-4172
KeywordsAlgal Proteins, Carbon Cycle, Carbon Dioxide, Carbonic Anhydrases, Chlamydomonas reinhardtii, Chloroplasts, Luminescent Proteins, Microscopy, Confocal, Photosynthesis, Plant Proteins, Ribulose-Bisphosphate Carboxylase
Abstract

Approximately one-third of global CO2 fixation is performed by eukaryotic algae. Nearly all algae enhance their carbon assimilation by operating a CO2-concentrating mechanism (CCM) built around an organelle called the pyrenoid, whose protein composition is largely unknown. Here, we developed tools in the model alga Chlamydomonas reinhardtii to determine the localizations of 135 candidate CCM proteins and physical interactors of 38 of these proteins. Our data reveal the identity of 89 pyrenoid proteins, including Rubisco-interacting proteins, photosystem I assembly factor candidates, and inorganic carbon flux components. We identify three previously undescribed protein layers of the pyrenoid: a plate-like layer, a mesh layer, and a punctate layer. We find that the carbonic anhydrase CAH6 is in the flagella, not in the stroma that surrounds the pyrenoid as in current models. These results provide an overview of proteins operating in the eukaryotic algal CCM, a key process that drives global carbon fixation.

DOI10.1016/j.cell.2017.08.044
Alternate JournalCell
PubMed ID28938113
PubMed Central IDPMC5616186
Grant ListDP2 GM119137 / GM / NIGMS NIH HHS / United States
S10 RR027425 / RR / NCRR NIH HHS / United States