气候变化领域集成服务门户(CCPortal): Rubisco proton production can drive the elevation of CO2 within condensates and carboxysomes

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DOI	10.1073/pnas.2014406118
	Rubisco proton production can drive the elevation of CO2 within condensates and carboxysomes
	Long B.M.; Förster B.; Pulsford S.B.; Price G.D.; Badger M.R.
发表日期	2021
ISSN	0027-8424
卷号	118 期号:18
英文摘要	Membraneless organelles containing the enzyme ribulose-1,5bisphosphate carboxylase/oxygenase (Rubisco) are a common feature of organisms utilizing CO2 concentrating mechanisms to enhance photosynthetic carbon acquisition. In cyanobacteria and proteobacteria, the Rubisco condensate is encapsulated in a proteinaceous shell, collectively termed a carboxysome, while some algae and hornworts have evolved Rubisco condensates known as pyrenoids. In both cases, CO2 fixation is enhanced compared with the free enzyme. Previous mathematical models have attributed the improved function of carboxysomes to the generation of elevated CO2 within the organelle via a colocalized carbonic anhydrase (CA) and inwardly diffusing HCO3−, which have accumulated in the cytoplasm via dedicated transporters. Here, we present a concept in which we consider the net of two protons produced in every Rubisco carboxylase reaction. We evaluate this in a reaction-diffusion compartment model to investigate functional advantages these protons may provide Rubisco condensates and carboxysomes, prior to the evolution of HCO3− accumulation. Our model highlights that diffusional resistance to reaction species within a condensate allows Rubisco-derived protons to drive the conversion of HCO3− to CO2 via colocalized CA, enhancing both condensate [CO2] and Rubisco rate. Protonation of Rubisco substrate (RuBP) and product (phosphoglycerate) plays an important role in modulating internal pH and CO2 generation. Application of the model to putative evolutionary ancestors, prior to contemporary cellular HCO3− accumulation, revealed photosynthetic enhancements along a logical sequence of advancements, via Rubisco condensation, to fully formed carboxysomes. Our model suggests that evolution of Rubisco condensation could be favored under low CO2 and low light environments. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Carboxysomes; Protein condensates; Protons; Pyrenoids; Rubisco
语种	英语
scopus关键词	bicarbonate; carbon dioxide; carbonate dehydratase; proton; ribulosebisphosphate carboxylase; Article; carboxylation; carboxysome; cell inclusion; cell pH; compartment model; controlled study; diffusion; enzyme mechanism; enzyme substrate; photosynthesis; polymerization; priority journal; protonation; pyrenoid; reaction diffusion model
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/238586
作者单位	Realizing Increased Photosynthetic Efficiency, Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia; Australian Research Council Centre of Excellence for Translational Photosynthesis, Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
推荐引用方式 GB/T 7714	Long B.M.,Förster B.,Pulsford S.B.,et al. Rubisco proton production can drive the elevation of CO2 within condensates and carboxysomes[J],2021,118(18).
APA	Long B.M.,Förster B.,Pulsford S.B.,Price G.D.,&Badger M.R..(2021).Rubisco proton production can drive the elevation of CO2 within condensates and carboxysomes.Proceedings of the National Academy of Sciences of the United States of America,118(18).
MLA	Long B.M.,et al."Rubisco proton production can drive the elevation of CO2 within condensates and carboxysomes".Proceedings of the National Academy of Sciences of the United States of America 118.18(2021).