The Kok Effect and Its Relationship to Photorespiration in Tobacco

1981 ◽  
Vol 36 (5-6) ◽  
pp. 450-454
Author(s):  
Ryuichi Ishii ◽  
Georg H. Schmid
Keyword(s):  
Mass Spectrometry ◽  
Structural Change ◽  
Light Intensity ◽  
Dark Respiration ◽  
Hill Reaction ◽  
Wild Type ◽  
Intensity Curve ◽  
Low Light ◽  
In The Wild ◽  
The Hill

Abstract The Kok effect of photosynthesis was investigated in different tobacco mutants. It was found that the breaks in the light intensity curve were always at or around 1000 lux in all plants tested regardless of the unit sizes which differed by a factor of 10. It was concluded that the photo­ receptor responsible for the effect must be present in the wild type and the chlorophyll deficient mutants in the same amount and is probably not chlorophyll. Due to the fact that the light dependency of the Hill reaction in isolated tobacco chloroplasts also shows a break at or around the “Kok intensity” it was concluded that probably a structural change of the photochemical apparatus around 1000 lux contributes to the effect. Measurement of 180 2-uptake by mass spectrometry at low light intensity shows at low CO2-concentration an enhancement of 180 2-uptake again at/around 1000 lux indicating that photorespiration starts to function at the “Kok intensity”. Due to the fact that 180 2-uptake remains constant at high CO2-concentrations the break in the photosynthetic light intensity curve cannot be due to an inhibition of “dark respiration” at low light intensities.

scholarly journals Identification and molecular characterization of a Chlamydomonas reinhardtii mutant that shows a light intensity dependent progressive chlorophyll deficiency

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 142
Author(s):  
Phillip B Grovenstein ◽  
Darryel A Wilson ◽  
Kathryn D Lankford ◽  
Kelsey A Gaston ◽  
Surangi Perera ◽  
...  
Keyword(s):  
Light Intensity ◽  
Insertional Mutagenesis ◽  
Protoporphyrin Ix ◽  
Model Organism ◽  
Genomic Region ◽  
Oxygenic Photosynthesis ◽  
Autotrophic Growth ◽  
Wild Type ◽  
Light Intensities ◽  
In The Wild

The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms. These tetrapyrroles are synthesized via a common branched pathway that involves mainly nuclear encoded enzymes. One of the enzymes in the pathway is Mg chelatase (MgChel) which inserts Mg2+ into protoporphyrin IX (PPIX, proto) to form Magnesium-protoporphyrin IX (MgPPIX, Mgproto), the first biosynthetic intermediate in the Chl branch. The GUN4 (genomes uncoupled 4) protein is not essential for the MgChel activity but has been shown to significantly stimulate its activity. We have isolated a light sensitive mutant, 6F14, by random DNA insertional mutagenesis. 6F14 cannot tolerate light intensities higher than 90-100 μmol photons m-2 s-1. It shows a light intensity dependent progressive photo-bleaching. 6F14 is incapable of photo-autotrophic growth under light intensity higher than 100 μmol photons m-2 s-1. PCR based analyses show that in 6F14 the insertion of the plasmid outside the GUN4 locus has resulted in a genetic rearrangement of the GUN4 gene and possible deletions in the genomic region flanking the GUN4 gene. Our gun4 mutant has a Chl content very similar to that in the wild type in the dark and is very sensitive to fluctuations in the light intensity in the environment unlike the earlier identified Chlamydomonas gun4 mutant. Complementation with a functional copy of the GUN4 gene restored light tolerance, Chl biosynthesis and photo-autotrophic growth under high light intensities in 6F14. 6F14 is the second gun4 mutant to be identified in C. reinhardtii. Additionally, we show that our two gun4 complements over-express the GUN4 protein and show a higher Chl content per cell compared to that in the wild type strain.

scholarly journals Decreased-activity mutants of phosphoglucose isomerase in the cytosol and chloroplast of Clarkia xantiana. Impact on mass-action ratios and fluxes to sucrose and starch, and estimation of Flux Control Coefficients and Elasticity Coefficients

1989 ◽  
Vol 261 (2) ◽  
pp. 457-467 ◽  
Author(s):  
A L Kruckeberg ◽  
H E Neuhaus ◽  
R Feil ◽  
L D Gottlieb ◽  
M Stitt
Keyword(s):  
Light Intensity ◽  
Starch Synthesis ◽  
Phosphoglucose Isomerase ◽  
Wild Type ◽  
Low Light ◽  
Subcellular Compartment ◽  
Flux Control Coefficients ◽  
Substrate Ratio ◽  
Control Coefficients ◽  
Clarkia Xantiana

1. Subcellular-compartment-specific decreased-activity mutants of phosphoglucose isomerase in Clarkia xantiana were used to analyse the control of sucrose and starch synthesis during photosynthesis. Mutants were available in which the plastid phosphoglucose isomerase complement is decreased to 75% or 50% of the wild-type level, and the cytosol complement to 64%, 36% or 18% of the wild-type level. 2. The effects on the [product]/[substrate] ratio and on fluxes to sucrose or starch and the rate of photosynthesis were studied with the use of saturating or limiting light intensity to impose a high or low flux through these pathways. 3. Removal of a small fraction of either phosphoglucose isomerase leads to a significant shift of the [product]/[substrate] ratio away, from equilibrium. We conclude that there is no ‘excess’ of enzyme over that needed to maintain its reactants reasonably close to equilibrium. 4. Decreased phosphoglucose isomerase activity can also alter the fluxes to starch or sucrose. However, the effect on flux does not correlate with the extent of disequilibrium, and also varies depending on the subcellular compartment and on the conditions. 5. The results were used to estimate Flux Control Coefficients for the chloroplast and cytosolic phosphoglucose isomerases. The chloroplast isoenzyme exerts control on the rate of starch synthesis and on photosynthesis in saturating light intensity and CO2, but not at low light intensity. The cytosolic enzyme only exerts significant control when its complement is decreased 3-5-fold, and differs from the plastid isoenzyme in exerting more control in low light intensity. It has a positive Control Coefficient for sucrose synthesis, and a negative Control Coefficient for starch synthesis. 6. The Elasticity Coefficients in vivo of the cytosolic phosphoglucose isomerase were estimated to lie between 5 and 8 in the wild-type. They decrease in mutants with a lowered complement of cytosolic phosphoglucose isomerase. 7. The implications of these results for regulation and for evolution are discussed.

scholarly journals Complexome profiling on the lpa2 mutant reveals insights into PSII biogenesis and new PSII associated proteins

2021 ◽  
Author(s):  
Benjamin Spaniol ◽  
Julia Lang ◽  
Benedikt Venn ◽  
Lara Schake ◽  
Frederik K Sommer ◽  
...  
Keyword(s):  
Complex Dynamics ◽  
Oxygen Evolving Complex ◽  
Cytochrome B6f Complex ◽  
Wild Type ◽  
Low Light ◽  
Chlorophyll Breakdown ◽  
Associated Proteins ◽  
In The Wild ◽  
Oxygen Evolving ◽  
B6f Complex

We have identified the homolog of LOW PSII ACCUMULATION 2 (LPA2) in Chlamydomonas. A Chlamydomonas lpa2 mutant grew slower in low light and was hypersensitive to high light. PSII maximum quantum efficiency was reduced by 38%. Synthesis and stability of newly made PSII core subunits D1, D2, CP43, and CP47 were not impaired. Complexome profiling revealed that in the mutant CP43 was reduced to ~23%, D1, D2, and CP47 to ~30% of wild-type levels, while small PSII core subunits and components of the oxygen evolving complex were reduced at most by factor two. PSII supercomplexes, dimers, and monomers were reduced to 7%, 26%, and 60% of wild-type levels, while RC47 was increased ~6-fold. Our data indicate that LPA2 acts at a step during PSII assembly without which PSII monomers and especially further assemblies become intrinsically unstable and prone to degradation. Levels of ATP synthase and LHCII were 29% and 27% higher in the mutant than in the wild type, whereas levels of the cytochrome b6f complex were unaltered. While the abundance of PSI core subunits and antennae hardly changed, LHCI antennae were more disconnected in the lpa2 mutant, presumably as an adaptive response to reduce excitation of PSI. The disconnection of LHCA2,9 together with PSAH and PSAG was the prime response, but independent and additional disconnection of LHCA1,3-8 along with PSAK occurred as well. Finally, based on co-migration profiles, we identified three novel putative PSII associated proteins with potential roles in regulating PSII complex dynamics, assembly, and chlorophyll breakdown.

Light Saturation of Growth and Photosynthesis of the Shade Plant Marchantia Polymorpha

1973 ◽  
Vol 12 (2) ◽  
pp. 391-401
Author(s):  
R. MACHE ◽  
S. LOISEAUX
Keyword(s):  
Growth Rate ◽  
Photosystem Ii ◽  
Light Intensity ◽  
Marchantia Polymorpha ◽  
Hill Reaction ◽  
Light Saturation ◽  
Shade Plant ◽  
Low Illumination ◽  
The Hill ◽  
Isolated Chloroplasts

The growth rate of the shade plant Marchantia was at its maximum for a low illumination, 2-3 x 103 lx, and was inhibited by an excess of light. Photosynthesis by intact thalli and by isolated chloroplasts of Marchantia was saturated by a light intensity of 2-3 x 103 lx. These isolated chloroplasts were able to carry on satisfactory rates of photosynthesis, up to 35 µM CO2/h/mg chlorophyll. The Hill reaction and photosystem II were also saturated by the same light intensities, demonstrating that the factor limiting the light saturation of photosynthesis is located in the chloroplast. The structure of chloroplasts was strongly modified by an excess of light, small grana and fret membranes being replaced by continuous grana.

Response of chlorina barley mutants to heat stress under low and high light

2003 ◽  
Vol 30 (5) ◽  
pp. 515 ◽  
Author(s):  
Katya Georgieva ◽  
Ivanka Fedina ◽  
Liliana Maslenkova ◽  
Violeta Peeva
Keyword(s):  
Heat Stress ◽  
Light Intensity ◽  
Photosynthetic Activity ◽  
High Light Intensity ◽  
High Light ◽  
O2 Evolution ◽  
Wild Type ◽  
Hordeum Vulgare L ◽  
Low Light ◽  
Low Light Intensity

Barley plants (Hordeum vulgare L.) of wild type and two chlorina mutants, chlorina 126 and chlorina f2, were subjected to 42°C for 5 h at light intensities of 100 and 1000 μmol photons m–2 s–1. The exposure of plants to heat stress at a light intensity of 100 μmol m–2 s–1 induced enormous proline accumulation, indicating that the effect of heat stress was stronger when it was combined with low light intensity. The functional activity of PSII, O2�evolution and flash-induced thermoluminescence B-band amplitude were strongly reduced when plants were exposed to heat at low light intensity. The results clearly showed that high light intensity had a protective effect on photosynthetic activity when barley plants were treated with high temperature. Comparison of the thermosensitivity of wild type plants and chlorina mutants revealed that O2 evolution in chlorina 126 and, especially, in chlorina f2 was more sensitive to heat than in wild type.

scholarly journals Physiological response of two different Chlamydomonas reinhardtii strains to light–dark rhythms

Botany ◽  
2016 ◽  
Vol 94 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Michael Sandmann ◽  
Andreas Garz ◽  
Ralf Menzel
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Cell Volume ◽  
Dark Respiration ◽  
Starch Content ◽  
Saturation Index ◽  
Cell Physiology ◽  
Wild Type ◽  
Cell Productivity ◽  
In The Wild ◽  
Entire Cell

Cells of a cell-wall deficient line (cw15-type) of Chlamydomonas reinhardtii and of the corresponding wild type were grown during repetitive light–dark cycles. In a direct comparison, both lines showed approximately the same relative biomass increase during light phase but the cw-line produced significantly more, and smaller, daughter cells. Throughout the light period the average cellular starch content, the cellular chlorophyll content, the cellular rate of dark respiration, and the cellular rate of photosynthesis of the cw-line was lower. Despite this, several non-cell volume related parameters like the development of starch content per cell volume were clearly different over time between the strains. Additionally, the chlorophyll-based photosynthesis rates were 2-fold higher in the mutant than in the wild-type cells, and the ratio of chlorophyll a to chlorophyll b as well as the light-saturation index were also consistently higher in the mutant cells. Differences in the starch content were also confirmed by single cell analyses using a sensitive SHG-based microscopy approach. In summary, the cw15-type mutant deviates from its genetic background in the entire cell physiology. Both lines should be used in further studies in comparative systems biology with focus on the detailed relation between cell volume increase, photosynthesis, starch metabolism, and daughter cell productivity.

scholarly journals Potential Plasticity of the Mannoprotein Repertoire Associated to Mycobacterium tuberculosis Virulence Unveiled by Mass Spectrometry-Based Glycoproteomics

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2348
Author(s):  
Laure Tonini ◽  
Bashir Sadet ◽  
Alexandre Stella ◽  
David Bouyssié ◽  
Jérôme Nigou ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mycobacterium Tuberculosis ◽  
Large Scale ◽  
Therapeutic Targets ◽  
Multidrug Resistant ◽  
Host Cells ◽  
Bacterial Protein ◽  
Wild Type ◽  
In The Wild ◽  
Resistant Strains

To date, Mycobacterium tuberculosis (Mtb) remains the world’s greatest infectious killer. The rise of multidrug-resistant strains stresses the need to identify new therapeutic targets to fight the epidemic. We previously demonstrated that bacterial protein-O-mannosylation is crucial for Mtb infectiousness, renewing the interest of the bacterial-secreted mannoproteins as potential drug-targetable virulence factors. The difficulty of inventorying the mannoprotein repertoire expressed by Mtb led us to design a stringent multi-step workflow for the reliable identification of glycosylated peptides by large-scale mass spectrometry-based proteomics. Applied to the differential analyses of glycoproteins secreted by the wild-type Mtb strain—and by its derived mutant invalidated for the protein-O-mannosylating enzyme PMTub—this approach led to the identification of not only most already known mannoproteins, but also of yet-unknown mannosylated proteins. In addition, analysis of the glycoproteome expressed by the isogenic recombinant Mtb strain overexpressing the PMTub gene revealed an unexpected mannosylation of proteins, with predicted or demonstrated functions in Mtb growth and interaction with the host cell. Since in parallel, a transient increased expression of the PMTub gene has been observed in the wild-type bacilli when infecting macrophages, our results strongly suggest that the Mtb mannoproteome may undergo adaptive regulation during infection of the host cells. Overall, our results provide deeper insights into the complexity of the repertoire of mannosylated proteins expressed by Mtb, and open the way to novel opportunities to search for still-unexploited potential therapeutic targets.

scholarly journals OCTAHEDRAL CRYSTALS IN PHYCOMYCES. II

1973 ◽  
Vol 57 (2) ◽  
pp. 278-288 ◽  
Author(s):  
T. Ootaki ◽  
J. J. Wolken
Keyword(s):  
Light Intensity ◽  
Gradient Centrifugation ◽  
Stage Iv ◽  
High Light Intensity ◽  
High Light ◽  
Wild Type ◽  
Buffer Solution ◽  
Phycomyces Blakesleeanus ◽  
Sucrose Density Gradient Centrifugation ◽  
In The Wild

"Phycomyces blakesleeanus" sporangiophores contain octahedral crystals throughout their cytoplasm and vacuole. More octahedral crystals were found in the wild-type strain G5 (+) than in the ß-carotene-deficient mutant C5 (-), and much more than in the mutant C141 (-), which is sensitive to only high light intensity. In the wild type, the number of crystals per sporangiophore increased until the sporangiophore reached stage IV, and then decreased. Stage I contained the most crystals per unit volume. Cultures grown in darkness had the maximum number of crystals. Under high light intensity, there was an overall reduction of crystals. The crystals are regular octahedrons. The crystals were isolated from the sporangiophores by a method of sucrose density-gradient centrifugation. They contain nearly 95% protein, are stable in organic solvents, but can be solubilized in buffer solution above pH 9.5 and below 2.5. The crystals weakly fluoresce with an emission peak at 540 nm, which is affected by irradiation with white light. Absorption spectra of freshly prepared crystals show absorption maxima around 265–285 nm, 350–380 nm, and 450–470 nm. These absorption peaks for the crystals are close to those of the phototropic and light-growth action spectra. These data suggest that the crystals may contain a flavoprotein which may be the photoreceptor pigment of "Phycomyces".

scholarly journals Involvement of the SppA1 Peptidase in Acclimation to Saturating Light Intensities in Synechocystis sp. Strain PCC 6803

2004 ◽  
Vol 186 (12) ◽  
pp. 3991-3999 ◽  
Author(s):  
E. Pojidaeva ◽  
V. Zinchenko ◽  
S. V. Shestakov ◽  
A. Sokolenko
Keyword(s):  
Light Intensity ◽  
Wild Type Strain ◽  
Wild Type ◽  
Additional Mechanism ◽  
Gene Encoding ◽  
Light Intensities ◽  
In The Wild ◽  
Pcc 6803

ABSTRACT The sll1703 gene, encoding an Arabidopsis homologue of the thylakoid membrane-associated SppA peptidase, was inactivated by interposon mutagenesis in Synechocystis sp. strain PCC 6803. Upon acclimation from a light intensity of 50 to 150 μE m−2 s−1, the mutant preserved most of its phycobilisome content, whereas the wild-type strain developed a bleaching phenotype due to the loss of about 40% of its phycobiliproteins. Using in vivo and in vitro experiments, we demonstrate that the ΔsppA1 strain does not undergo the cleavage of the LR 33 and LCM 99 linker proteins that develops in the wild type exposed to increasing light intensities. We conclude that a major contribution to light acclimation under a moderate light regime in cyanobacteria originates from an SppA1-mediated cleavage of phycobilisome linker proteins. Together with changes in gene expression of the major phycobiliproteins, it contributes an additional mechanism aimed at reducing the content in phycobilisome antennae upon acclimation to a higher light intensity.

Sign in / Sign up

Export Citation Format

Share Document