Modelling the pyrenoid-based CO-concentrating mechanism provides insights into its operating principles and a roadmap for its engineering into crops.

TitleModelling the pyrenoid-based CO-concentrating mechanism provides insights into its operating principles and a roadmap for its engineering into crops.
Publication TypeJournal Article
Year of Publication2022
AuthorsFei, C, Wilson, AT, Mangan, NM, Wingreen, NS, Jonikas, MC
JournalNat Plants
Volume8
Issue5
Pagination583-595
Date Published2022 05
ISSN2055-0278
KeywordsCarbon Dioxide, Chlamydomonas reinhardtii, Chloroplasts, Crops, Agricultural, Photosynthesis, Plastids, Ribulose-Bisphosphate Carboxylase
Abstract

<p>Many eukaryotic photosynthetic organisms enhance their carbon uptake by supplying concentrated CO to the CO-fixing enzyme Rubisco in an organelle called the pyrenoid. Ongoing efforts seek to engineer this pyrenoid-based CO-concentrating mechanism (PCCM) into crops to increase yields. Here we develop a computational model for a PCCM on the basis of the postulated mechanism in the green alga Chlamydomonas reinhardtii. Our model recapitulates all Chlamydomonas PCCM-deficient mutant phenotypes and yields general biophysical principles underlying the PCCM. We show that an effective and energetically efficient PCCM requires a physical barrier to reduce pyrenoid CO leakage, as well as proper enzyme localization to reduce futile cycling between CO and HCO. Importantly, our model demonstrates the feasibility of a purely passive CO uptake strategy at air-level CO, while active HCO uptake proves advantageous at lower CO levels. We propose a four-step engineering path to increase the rate of CO fixation in the plant chloroplast up to threefold at a theoretical cost of only 1.3 ATP per CO fixed, thereby offering a framework to guide the engineering of a PCCM into land plants.</p>

DOI10.1038/s41477-022-01153-7
Alternate JournalNat Plants
PubMed ID35596080
PubMed Central IDPMC9122830
Grant ListR01 GM140032 / GM / NIGMS NIH HHS / United States
55108535 / HHMI / Howard Hughes Medical Institute / United States