Search results for "RuBisCO"

C4-like photosynthesis and the effects of leaf senescence on C4-like physiology in Sesuvium sesuvioides (Aizoaceae).

2019

Sesuvium sesuvioides represents a young C4 lineage with C4-like metabolism: CO2 compensation points range between C4 and C3–C4 intermediate values, and Rubisco was detected in bundle sheath and mesophyll.

The Water to Water Cycles in Microalgae.

2016

In oxygenic photosynthesis, light produces ATP plus NADPH via linear electron transfer, i.e. the in-series activity of the two photosystems: PSI and PSII. This process, however, is thought not to be sufficient to provide enough ATP per NADPH for carbon assimilation in the Calvin-Benson-Bassham cycle. Thus, it is assumed that additional ATP can be generated by alternative electron pathways. These circuits produce an electrochemical proton gradient without NADPH synthesis, and, although they often represent a small proportion of the linear electron flow, they could have a huge importance in optimizing CO2 assimilation. In Viridiplantae, there is a consensus that alternative electron flow comp…

Changes in lipid and carotenoid metabolism in Chlamydomonas reinhardtii during induction of CO2-concentrating mechanism: Cellular response to low CO2…

2020

Photosynthetic organisms strictly depend on CO2 availability and the CO2:O2 ratio, as both CO2/O2 compete for catalytic site of Rubisco. Green alga Chlamydomonas reinhardtii, can overcome CO2 shortage by inducing CO2-concentrating mechanism (CCM). Cells transferred to low-CO2 are subjected to light-driven oxidative stress due to decrease in the electron sink. Response to environmental perturbations is mediated to some extent by changes in the lipid and carotenoid metabolism. We thus hypothesize that when cells are challenged with changes in CO2 availability, changes in the lipidome and carotenoids profile occur. These changes expected to be transient, when CCM is activated, CO2 limitation w…

Carbon isotope composition of plant photosynthetic tissues reflects a Crassulacean Acid Metabolism (CAM) continuum in the majority of CAM lineages

2021

Abstract The stable carbon isotope composition of plant tissues, commonly expressed as δ13C, holds a wealth of information about photosynthetic pathway, water relations and stress physiology. Crassulacean acid metabolism (CAM) is a derived form of photosynthesis that allows plants to fix carbon at a higher water-use efficiency compared to the ancestral C3 photosynthesis. While the central carbon-fixing enzyme of C3 plants, Rubisco, strongly discriminates against the heavy 13C isotope, CAM is characterized by a dual use of Rubisco and the much less discriminating PEP carboxylase as carbon-fixing enzymes, causing the δ13C values of CAM plant tissues to be generally less negative than those fo…

Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

2017

Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb) and average intergenic spacer length (20 bp) of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybri…

2012

Abstract. Global change forces ecosystems to adapt to elevated atmospheric concentrations of carbon dioxide (CO2). We understand that carbonyl sulfide (COS), a trace gas which is involved in building up the stratospheric sulfate aerosol layer, is taken up by vegetation with the same triad of the enzymes which are metabolizing CO2, i.e. ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEP-Co) and carbonic anhydrase (CA). Therefore, we discuss a physiological/biochemical acclimation of these enzymes affecting the sink strength of vegetation for COS. We investigated the acclimation of two European tree species, Fagus sylvatica and Quercus ilex, grown …

The combined effects of CO2, ozone and drought on rubisco and nitrogen metabolism of young oak trees (Quercus petraea) A phytotron study

1998

Abstract In this phytotron experiment we investigated the influence of increased CO 2 , O 3 and drought on the content of soluble proteins and some enzymes of carbon and nitrogen metabolism. We found that the amounts of soluble proteins and the large subunit of the rubisco per fresh weight in young oak leaves declined under conditions of increasing levels of CO 2 and after temporary water stress. The activities of nitrite reductase and glutamine synthetase were reduced when O 3 and CO 2 levels were raised.

Evidence for the Existence of a Pseudogene for the Large Subunit of Rubisco within the Chloroplast DNA of Norway Spruce (Picea Abies)

1998

Many hundreds of genes are involved in the synthesis, maintenance and degradation of chloroplasts. Although quite a number of these genes are located in the chloroplast genome, by far the greater proportion is present in the nuclear genome. The sizes of chloroplast DNAs (cpDNA) were estimated from restriction enzyme mapping studies and the complete sequences of different cpDNAs from diverse plant lineages have been determined to date (Marchantia polymorpha [1], Nicotiana tabacum [2], Oryza saliva [3], Epifagus virginiana [4], Euglena gracilis [5], Pinus thunbergii [6], Porphyra purpurea [7], Odontella sinensis [8], Zea mays [9], Chlorella vulgaris [10]).

The effect of light intensities on the transcript level of proteins involved in photosynthesis in mustard plants

1996

Summary The influence of light quantity on the steady-state levels of plastid encoded transcripts was examined during the development of primary leaves from mustard ( Sinapis alba ) plants. RbcL mRNA, petA mRNA, and psbA mRNA, which encode the large subunit (LSU) of Rubisco, Cyt f of the Cyt b6/f complex, and D1 protein of PS II were investigated in leaves grown under high-light (HL) or low-light (LL) conditions. Additionally, the nuclear encoded 25 S rRNA was quantified. As a proportion of total RNA, the levels of 25 S rRNA, rbcL mRNA, petA mRNA, and psbA mRNA did not differ substantially in the HL versus LL plants. During leaf ontogenesis, though, the proportion of psbA mRNA in total RNA …

Structural and functional consequences of the replacement of proximal residues Cys172 and Cys192 in the large subunit of ribulose-1,5-bisphosphate ca…

2008

Proximal Cys(172) and Cys(192) in the large subunit of the photosynthetic enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase; EC 4.1.1.39) are evolutionarily conserved among cyanobacteria, algae and higher plants. Mutation of Cys(172) has been shown to affect the redox properties of Rubisco in vitro and to delay the degradation of the enzyme in vivo under stress conditions. Here, we report the effect of the replacement of Cys(172) and Cys(192) by serine on the catalytic properties, thermostability and three-dimensional structure of Chlamydomonas reinhardtii Rubisco. The most striking effect of the C172S substitution was an 11% increase in the specificity factor when compared wi…