scholarly journals Condensation of Rubisco into a proto-pyrenoid in higher plant chloroplasts

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicky Atkinson ◽  
Yuwei Mao ◽  
Kher Xing Chan ◽  
Alistair J. McCormick
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Recent Work ◽  
Single Phase ◽  
Inorganic Carbon ◽  
Higher Plants ◽  
Initial Step ◽  
Operating Efficiency ◽  
Higher Plant ◽  
Spontaneous Condensation ◽  
Concentrating Mechanism

AbstractPhotosynthetic CO2 fixation in plants is limited by the inefficiency of the CO2-assimilating enzyme Rubisco. In most eukaryotic algae, Rubisco aggregates within a microcompartment known as the pyrenoid, in association with a CO2-concentrating mechanism that improves photosynthetic operating efficiency under conditions of low inorganic carbon. Recent work has shown that the pyrenoid matrix is a phase-separated, liquid-like condensate. In the alga Chlamydomonas reinhardtii, condensation is mediated by two components: Rubisco and the linker protein EPYC1 (Essential Pyrenoid Component 1). Here, we show that expression of mature EPYC1 and a plant-algal hybrid Rubisco leads to spontaneous condensation of Rubisco into a single phase-separated compartment in Arabidopsis chloroplasts, with liquid-like properties similar to a pyrenoid matrix. This work represents a significant initial step towards enhancing photosynthesis in higher plants by introducing an algal CO2-concentrating mechanism, which is predicted to significantly increase the efficiency of photosynthetic CO2 uptake.

scholarly journals Condensation of Rubisco into a proto-pyrenoid in higher plant chloroplasts

2020 ◽  
Author(s):  
Nicky Atkinson ◽  
Yuwei Mao ◽  
Kher Xing Chan ◽  
Alistair J. McCormick
Keyword(s):  
Higher Plants ◽  
Initial Step ◽  
Small Subunit ◽  
Operating Efficiency ◽  
Higher Plant ◽  
Bisphosphate Carboxylase ◽  
Spontaneous Condensation ◽  
Concentrating Mechanism ◽  
Chloroplast Stroma ◽  
Almost All

SummaryPhotosynthetic CO2 fixation in plants is limited by the inefficiency of the CO2-assimilating enzyme Rubisco (D-ribulose-1,5-bisphosphate carboxylase/ oxygenase)1–3. In plants possessing the C3 pathway, which includes most major staple crops, Rubisco is typically evenly distributed throughout the chloroplast stroma. However, in almost all eukaryotic algae Rubisco aggregates within a microcompartment known as the pyrenoid, in association with a CO2-concentrating mechanism that improves photosynthetic operating efficiency under conditions of low inorganic carbon4. Recent work has shown that the pyrenoid matrix is a phase-separated, liquid-like condensate5. In the alga Chlamydomonas reinhardtii, condensation is mediated by two components: Rubisco and the linker protein EPYC1 (Essential Pyrenoid Component 1)6,7. Here we show that expression of mature EPYC1 and a plant-algal hybrid Rubisco leads to spontaneous condensation of Rubisco into a single phase-separated compartment in Arabidopsis chloroplasts, with liquid-like properties similar to a pyrenoid matrix. The condensate displaces the thylakoid membranes and is enriched in hybrid Rubisco containing the algal Rubisco small subunit required for phase separation. Promisingly, photosynthetic CO2 fixation and growth is not impaired in stable transformants compared to azygous segregants. These observations represent a significant initial step towards enhancing photosynthesis in higher plants by introducing an algal CO2-concentrating mechanism, which is predicted to significantly increase the efficiency of photosynthetic CO2 uptake8,9.

Adaptation of a Chlamydomonas mutant with reduced rate of photorespiration to different concentrations of CO2

2005 ◽  
Vol 83 (7) ◽  
pp. 834-841 ◽  
Author(s):  
Kensaku Suzuki ◽  
Hidenori Onodera
Keyword(s):  
Chlorophyll Fluorescence ◽  
Chlamydomonas Reinhardtii ◽  
Inorganic Carbon ◽  
Electron Flow ◽  
Effective Quantum Yield ◽  
Wild Type ◽  
Chlorophyll Fluorescence Parameters ◽  
Phosphoglycolate Phosphatase ◽  
Concentrating Mechanism ◽  
Type Strains

It has been widely accepted that Chlamydomonas reinhardtii cells utilize inorganic carbon very efficiently for photosynthesis by operating a CO2-concentrating mechanism (CCM) under conditions of limited CO2. To help define the mechanism, 7FR2N, one of the suppressor double mutants of phosphoglycolate phosphatase-deficient (pgp1) mutants that have a reduced photorespiration rate (RPR) was crossed with wild-type strains to generate the strain N21 as a single RPR mutant. The comparison of photosynthetic characteristics with wild-type strains after the cells adapted to different concentrations of CO2 revealed that photosynthetic affinity for inorganic carbon was higher than that in wild-type strains after adaptation to concentrations between 50 µL·L–1 CO2 and 5% CO2. Chlorophyll fluorescence parameters were also compared, and the biggest difference between N21 and the wild-type strains was observed in the photochemical quenching and effective quantum yield of photosystem II (ΔF/Fm′) at the CO2 compensation point. These values in N21 increased in a similar manner to the photosynthetic affinity for CO2, and increased significantly when the cells adapted to low-CO2 levels, whereas the values in the wild-type strains were apparently lower without any significant changes, regardless of the CO2 concentrations to which they were adapted. Although it was not clear if a nonphotochemical quenching parameter (NPQ) in N21 was higher than that in wild-type strains, NPQ increased coincidentally with the increase in photosynthetic affinity for inorganic carbon when the CO2 concentrations to which the strains were adapted decreased, in both the mutant and wild-type strain, suggesting that this form of NPQ reflects the operation of CCM in certain conditions. Possible candidates for the RPR mutation and the relationship between CCM and photosynthetic electron flow are discussed.Key words: Chlamydomonas reinhardtii, chlorophyll fluorescence, CO2-concentrating mechanism, low-CO2 responsive gene, phosphoglycolate phosphatase, photorespiration.

scholarly journals The small RNA locus map for Chlamydomonas reinhardtii

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242516
Author(s):  
Sebastian Y. Müller ◽  
Nicholas E. Matthews ◽  
Adrian A. Valli ◽  
David C. Baulcombe
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Genome Stability ◽  
Higher Plants ◽  
Multiple Correspondence Analysis ◽  
Regulation Of Gene Expression ◽  
Transcriptional Gene Silencing ◽  
Evolutionary Divergence ◽  
Learning Approaches ◽  
Higher Plant ◽  
Systematic Classification

Small (s)RNAs play crucial roles in the regulation of gene expression and genome stability across eukaryotes where they direct epigenetic modifications, post-transcriptional gene silencing, and defense against both endogenous and exogenous viruses. It is known that Chlamydomonas reinhardtii, a well-studied unicellular green algae species, possesses sRNA-based mechanisms that are distinct from those of land plants. However, definition of sRNA loci and further systematic classification is not yet available for this or any other algae. Here, using data-driven machine learning approaches including Multiple Correspondence Analysis (MCA) and clustering, we have generated a comprehensively annotated and classified sRNA locus map for C. reinhardtii. This map shows some common characteristics with higher plants and animals, but it also reveals distinct features. These results are consistent with the idea that there was diversification in sRNA mechanisms after the evolutionary divergence of algae from higher plant lineages.

scholarly journals Structure of a C2S2M2N2-type PSII–LHCII supercomplex from the green alga Chlamydomonas reinhardtii

2019 ◽  
Vol 116 (42) ◽  
pp. 21246-21255 ◽  
Author(s):  
Liangliang Shen ◽  
Zihui Huang ◽  
Shenghai Chang ◽  
Wenda Wang ◽  
Jingfen Wang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Higher Plants ◽  
Huge Number ◽  
Higher Plant ◽  
Low Light ◽  
Green Algal ◽  
Light Harvesting Antenna ◽  
Energy Transfer Pathway

Photosystem II (PSII) in the thylakoid membranes of plants, algae, and cyanobacteria catalyzes light-induced oxidation of water by which light energy is converted to chemical energy and molecular oxygen is produced. In higher plants and most eukaryotic algae, the PSII core is surrounded by variable numbers of light-harvesting antenna complex II (LHCII), forming a PSII–LHCII supercomplex. In order to harvest energy efficiently at low–light-intensity conditions under water, a complete PSII–LHCII supercomplex (C2S2M2N2) of the green alga Chlamydomonas reinhardtii (Cr) contains more antenna subunits and pigments than the dominant PSII–LHCII supercomplex (C2S2M2) of plants. The detailed structure and energy transfer pathway of the Cr-PSII–LHCII remain unknown. Here we report a cryoelectron microscopy structure of a complete, C2S2M2N2-type PSII–LHCII supercomplex from C. reinhardtii at 3.37-Å resolution. The results show that the Cr-C2S2M2N2 supercomplex is organized as a dimer, with 3 LHCII trimers, 1 CP26, and 1 CP29 peripheral antenna subunits surrounding each PSII core. The N-LHCII trimer partially occupies the position of CP24, which is present in the higher-plant PSII–LHCII but absent in the green alga. The M trimer is rotated relative to the corresponding M trimer in plant PSII–LHCII. In addition, some unique features were found in the green algal PSII core. The arrangement of a huge number of pigments allowed us to deduce possible energy transfer pathways from the peripheral antennae to the PSII core.

scholarly journals Mapping the Algal Secret Genome: The small RNA Locus Map for Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Sebastian Y. Müller ◽  
Nicholas E. Matthews ◽  
Adrian A. Valli ◽  
David C. Baulcombe
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Genome Stability ◽  
Higher Plants ◽  
Multiple Correspondence Analysis ◽  
Regulation Of Gene Expression ◽  
Transcriptional Gene Silencing ◽  
Evolutionary Divergence ◽  
Learning Approaches ◽  
Higher Plant ◽  
Systematic Classification

AbstractSmall (s)RNAs play crucial roles in the regulation of gene expression and genome stability across eukaryotes where they direct epigenetic modifications, post-transcriptional gene silencing, and defense against both endogenous and exogenous viruses. The green alga Chlamydomonas reinhardtii is a well-studied unicellular alga species with sRNA-based mechanisms that are distinct from those of land plants. It is, therefore, a good model to study sRNA evolution but a systematic classification of sRNA mechanisms is lacking in this and any other algae. Here, using data-driven machine learning approaches including Multiple Correspondence Analysis (MCA) and clustering, we have generated a comprehensively annotated and classified sRNA locus map for C. reinhardtii. This map shows some common characteristics with higher plants and animals, but it also reveals distinct features. These results are consistent with the idea that there was diversification in sRNA mechanisms after the evolutionary divergence of algae from higher plant lineages.

Sign in / Sign up

Export Citation Format

Share Document