scholarly journals Transport Proteins Enabling Plant Photorespiratory Metabolism

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 880
Author(s):  
Franziska Kuhnert ◽  
Urte Schlüter ◽  
Nicole Linka ◽  
Marion Eisenhut
Keyword(s):  
Carbon Dioxide ◽  
Transport Proteins ◽  
Repair Pathway ◽  
Bisphosphate Carboxylase ◽  
Photosynthetic Organisms ◽  
Channel Proteins ◽  
Promising Target ◽  
Toxic Product ◽  
C4 Metabolism ◽  
Metabolite Channeling

Photorespiration (PR) is a metabolic repair pathway that acts in oxygenic photosynthetic organisms to degrade a toxic product of oxygen fixation generated by the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase. Within the metabolic pathway, energy is consumed and carbon dioxide released. Consequently, PR is seen as a wasteful process making it a promising target for engineering to enhance plant productivity. Transport and channel proteins connect the organelles accomplishing the PR pathway—chloroplast, peroxisome, and mitochondrion—and thus enable efficient flux of PR metabolites. Although the pathway and the enzymes catalyzing the biochemical reactions have been the focus of research for the last several decades, the knowledge about transport proteins involved in PR is still limited. This review presents a timely state of knowledge with regard to metabolite channeling in PR and the participating proteins. The significance of transporters for implementation of synthetic bypasses to PR is highlighted. As an excursion, the physiological contribution of transport proteins that are involved in C4 metabolism is discussed.

scholarly journals Macroalgae

Encyclopedia ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 177-188
Author(s):  
Leonel Pereira
Keyword(s):  
Carbon Dioxide ◽  
Chlorophyll A ◽  
Red Algae ◽  
Great Variability ◽  
Marine Macroalgae ◽  
Brown Macroalgae ◽  
Green Macroalgae ◽  
Red Macroalgae ◽  
Photosynthetic Organisms ◽  
Green Pigments

What are algae? Algae are organisms that perform photosynthesis; that is, they absorb carbon dioxide and release oxygen (therefore they have chlorophyll, a group of green pigments used by photosynthetic organisms that convert sunlight into energy via photosynthesis) and live in water or in humid places. Algae have great variability and are divided into microalgae, small in size and only visible through a microscope, and macroalgae, which are larger in size, up to more than 50 m (the maximum recorded was 65 m), and have a greater diversity in the oceans. Thus, the term “algae” is commonly used to refer to “marine macroalgae or seaweeds”. It is estimated that 1800 different brown macroalgae, 6200 red macroalgae, and 1800 green macroalgae are found in the marine environment. Although the red algae are more diverse, the brown ones are the largest.

scholarly journals The regulation of the air: a hypothesis

2011 ◽  
Vol 3 (2) ◽  
pp. 769-788 ◽  
Author(s):  
E. G. Nisbet ◽  
C. M. R. Fowler ◽  
R. E. R. Nisbet
Keyword(s):  
Carbon Dioxide ◽  
Natural Selection ◽  
Surface Temperature ◽  
Atmospheric Pressure ◽  
Nitrogen Fixing ◽  
Bisphosphate Carboxylase ◽  
Global Surface Temperature ◽  
Global Surface ◽  
Evolution Of Photosynthesis

Abstract. We propose the hypothesis that natural selection, acting on the specificity of rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) for carbon dioxide over oxygen, has controlled the CO2:O2 ratio of the atmosphere since the evolution of photosynthesis and has also sustained the Earth's greenhouse-set surface temperature. Rubisco works in partnership with the nitrogen-fixing enzyme nitrogenase to control atmospheric pressure. Together, these two enzymes control global surface temperature and indirectly the pH and oxygenation of the ocean. Thus, the co-evolution of these two enzymes may have produced clement conditions on the Earth's surface, allowing life to be sustained.

scholarly journals Role of Microalgae in Global CO2 Sequestration: Physiological Mechanism, Recent Development, Challenges, and Future Prospective

2021 ◽  
Vol 13 (23) ◽  
pp. 13061
Author(s):  
Ravindra Prasad ◽  
Sanjay Kumar Gupta ◽  
Nisha Shabnam ◽  
Carlos Yure B. Oliveira ◽  
Arvind Kumar Nema ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Sequestration ◽  
Carbon Concentration ◽  
Carbon Dioxide Emissions ◽  
Atmospheric Carbon Dioxide ◽  
Graphical Model ◽  
Renewable Energy Sources ◽  
Physiological Mechanism ◽  
High Concentration ◽  
Bisphosphate Carboxylase

The rising concentration of global atmospheric carbon dioxide (CO2) has severely affected our planet’s homeostasis. Efforts are being made worldwide to curb carbon dioxide emissions, but there is still no strategy or technology available to date that is widely accepted. Two basic strategies are employed for reducing CO2 emissions, viz. (i) a decrease in fossil fuel use, and increased use of renewable energy sources; and (ii) carbon sequestration by various biological, chemical, or physical methods. This review has explored microalgae’s role in carbon sequestration, the physiological apparatus, with special emphasis on the carbon concentration mechanism (CCM). A CCM is a specialized mechanism of microalgae. In this process, a sub-cellular organelle known as pyrenoid, containing a high concentration of Ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco), helps in the fixation of CO2. One type of carbon concentration mechanism in Chlamydomonas reinhardtii and the association of pyrenoid tubules with thylakoids membrane is represented through a typical graphical model. Various environmental factors influencing carbon sequestration in microalgae and associated techno-economic challenges are analyzed critically.

scholarly journals Probing Light-Dependent Regulation of the Calvin Cycle Using a Multi-Omics Approach

2021 ◽  
Vol 12 ◽  
Author(s):  
Nathaphon Yu King Hing ◽  
Uma K. Aryal ◽  
John A. Morgan
Keyword(s):  
Light Intensity ◽  
Atmospheric Carbon Dioxide ◽  
Metabolic Flux ◽  
Calvin Cycle ◽  
Model Organism ◽  
Flux Analysis ◽  
Photosynthetic Organisms ◽  
Light Intensities ◽  
External Conditions ◽  
Metabolite Channeling

Photoautotrophic microorganisms are increasingly explored for the conversion of atmospheric carbon dioxide into biomass and valuable products. The Calvin-Benson-Bassham (CBB) cycle is the primary metabolic pathway for net CO2 fixation within oxygenic photosynthetic organisms. The cyanobacteria, Synechocystis sp. PCC 6803, is a model organism for the study of photosynthesis and a platform for many metabolic engineering efforts. The CBB cycle is regulated by complex mechanisms including enzymatic abundance, intracellular metabolite concentrations, energetic cofactors and post-translational enzymatic modifications that depend on the external conditions such as the intensity and quality of light. However, the extent to which each of these mechanisms play a role under different light intensities remains unclear. In this work, we conducted non-targeted proteomics in tandem with isotopically non-stationary metabolic flux analysis (INST-MFA) at four different light intensities to determine the extent to which fluxes within the CBB cycle are controlled by enzymatic abundance. The correlation between specific enzyme abundances and their corresponding reaction fluxes is examined, revealing several enzymes with uncorrelated enzyme abundance and their corresponding flux, suggesting flux regulation by mechanisms other than enzyme abundance. Additionally, the kinetics of 13C labeling of CBB cycle intermediates and estimated inactive pool sizes varied significantly as a function of light intensity suggesting the presence of metabolite channeling, an additional method of flux regulation. These results highlight the importance of the diverse methods of regulation of CBB enzyme activity as a function of light intensity, and highlights the importance of considering these effects in future kinetic models.

scholarly journals Multi-layer Regulation of Rubisco in Response to Altered Carbon Status in Synechococcus elongatus PCC 7942

2021 ◽  
Author(s):  
Amit K Singh ◽  
María Santos-Merino ◽  
Jonathan K Sakkos ◽  
Berkley J Walker ◽  
Daniel C. Ducat
Keyword(s):  
Synechococcus Elongatus ◽  
Photosynthetic Parameters ◽  
Rubisco Activity ◽  
Bisphosphate Carboxylase ◽  
Regulatory Pathways ◽  
Photosynthetic Organisms ◽  
Regulatory Processes ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942 ◽  
Storage Pools

Photosynthetic organisms possess a variety of mechanisms to achieve balance between absorbed light (source) and the capacity to metabolically utilize or dissipate this energy (sink). While regulatory processes that detect changes in metabolic status/balance are relatively well-studied in plants, analogous pathways remain poorly characterized in photosynthetic microbes. Herein, we explore systemic changes that result from alterations in carbon availability in the model cyanobacterium Synechococcus elongatus PCC 7942 by taking advantage of an engineered strain where influx/efflux of a central carbon metabolite, sucrose, can be regulated experimentally. We observe that induction of a high-flux sucrose export pathway leads to depletion of internal carbon storage pools (glycogen), and concurrent increases in photosynthetic parameters. Further, a proteome-wide analysis and fluorescence reporter-based analysis revealed that upregulated factors following the activation of the metabolic sink are strongly concentrated on ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) and axillary modules involved in Rubisco maturation. Carboxysome number and Rubisco activity also increase following engagement of sucrose secretion. Conversely, reversing the flux of sucrose by feeding exogenous sucrose heterologously results in increased glycogen pools, decreased Rubisco abundance, decreased photosystem II quantum efficiency, and carboxysome reorganization. Our data suggest that Rubisco activity and organization are key outputs connected to regulatory pathways involved in metabolic balancing in cyanobacteria.

scholarly journals Obtaining Urea from Effluents of Gold Cyanidation Process

2019 ◽  
Vol 16 (1) ◽  
pp. 43-47
Author(s):  
CARLOS DARIO LOPEZ RAMIREZ ◽  
DAIRO E. CHAVERRA ◽  
OSCAR JAIME RESTREPO BAENA
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Precious Metal ◽  
Extraction Process ◽  
Point Of View ◽  
Metal Extraction ◽  
Solution Temperature ◽  
Ammonia Gas ◽  
Toxic Product ◽  
Cyanide Solutions

Cyanide is one of the most used reagents in the precious metal extraction process; as well as the most efficient from the point of view of the dissolution process, but it is also a toxic product that requires a lot of care in handling. Likewise, the residual solutions of the process must be followed because they can be a risk of contamination of water, animals and human health. In the artisanal processes of obtaining gold and silver, neutralization of the residual solutions is used to passivate the present cyanide. During this process ammonium cyanate is formed which decomposes rapidly in the presence of air and sunlight in carbon dioxide and ammonia gas, contributing to the greenhouse effect. In this work, the use of the ammonium cyanate obtained in the process of neutralization of the cyanide solutions as a reagent to obtain urea is proposed. Urea was obtained indirectly through the use of the reagent kit UREA/BUN-COLOR. The process is effective at pH ≤ 4.5 with a rapid increase in solution temperature and the addition of hydrogen peroxide. The urea crystals begin to form at 50°C. The cyanide/urea ratio obtained was 1/7.5.

scholarly journals Autotrophic Carbon Dioxide Fixation via the Calvin-Benson-Bassham Cycle by the Denitrifying Methanotroph “Candidatus Methylomirabilis oxyfera”

2014 ◽  
Vol 80 (8) ◽  
pp. 2451-2460 ◽  
Author(s):  
Olivia Rasigraf ◽  
Dorien M. Kool ◽  
Mike S. M. Jetten ◽  
Jaap S. Sinninghe Damsté ◽  
Katharina F. Ettwig
Keyword(s):  
Carbon Dioxide ◽  
Enrichment Culture ◽  
Carbon Assimilation ◽  
Carbon Dioxide Fixation ◽  
Oxidation Activity ◽  
Bisphosphate Carboxylase ◽  
Content Type ◽  
Whole Cells ◽  
Cell Extracts ◽  
Key Enzyme

ABSTRACTMethane is an important greenhouse gas and the most abundant hydrocarbon in the Earth's atmosphere. Methanotrophic microorganisms can use methane as their sole energy source and play a crucial role in the mitigation of methane emissions in the environment. “CandidatusMethylomirabilis oxyfera” is a recently described intra-aerobic methanotroph that is assumed to use nitric oxide to generate internal oxygen to oxidize methane via the conventional aerobic pathway, including the monooxygenase reaction. Previous genome analysis has suggested that, like the verrucomicrobial methanotrophs, “Ca.Methylomirabilis oxyfera” encodes and transcribes genes for the Calvin-Benson-Bassham (CBB) cycle for carbon assimilation. Here we provide multiple independent lines of evidence for autotrophic carbon dioxide fixation by “Ca.Methylomirabilis oxyfera” via the CBB cycle. The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), a key enzyme of the CBB cycle, in cell extracts from an “Ca.Methylomirabilis oxyfera” enrichment culture was shown to account for up to 10% of the total methane oxidation activity. Labeling studies with whole cells in batch incubations supplied with either13CH4or [13C]bicarbonate revealed that “Ca.Methylomirabilis oxyfera” biomass and lipids became significantly more enriched in13C after incubation with13C-labeled bicarbonate (and unlabeled methane) than after incubation with13C-labeled methane (and unlabeled bicarbonate), providing evidence for autotrophic carbon dioxide fixation. Besides this experimental approach, detailed genomic and transcriptomic analysis demonstrated an operational CBB cycle in “Ca.Methylomirabilis oxyfera.” Altogether, these results show that the CBB cycle is active and plays a major role in carbon assimilation by “Ca.Methylomirabilis oxyfera” bacteria. Our results suggest that autotrophy might be more widespread among methanotrophs than was previously assumed and implies that a methanotrophic community in the environment is not necessarily revealed by13C-depleted lipids.

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