Search results for "Reinhardt"
showing 10 items of 40 documents
Mutational analysis of eggplant latent viroid RNA processing in Chlamydomonas reinhardtii chloroplast.
2009
Viroids of the family Avsunviroidae, such as eggplant latent viroid (ELVd), contain hammerhead ribozymes and replicate in the chloroplasts of the host plant through an RNA-based symmetrical rolling-circle mechanism in which oligomeric RNAs of both polarity are processed to monomeric linear RNAs (by cleavage) and to monomeric circular RNAs (by ligation). Using an experimental system consisting of transplastomic lines of the alga Chlamydomonas reinhardtii, a mutational analysis of sequence and structural elements in the ELVd molecule that are involved in transcript processing in vivo in a chloroplastic context was carried out. A collection of six insertion and three deletion ELVd mutants was …
Genome-Based Examination of Chlorophyll and Carotenoid Biosynthesis in Chlamydomonas reinhardtii
2005
Abstract The unicellular green alga Chlamydomonas reinhardtii is a particularly important model organism for the study of photosynthesis since this alga can grow heterotrophically, and mutants in photosynthesis are therefore conditional rather than lethal. The recently developed tools for genomic analyses of this organism have allowed us to identify most of the genes required for chlorophyll and carotenoid biosynthesis and to examine their phylogenetic relationships with homologous genes from vascular plants, other algae, and cyanobacteria. Comparative genome analyses revealed some intriguing features associated with pigment biosynthesis in C. reinhardtii; in some cases, there are additiona…
A lycopene β-cyclase/lycopene ε-cyclase/light-harvesting complex-fusion protein from the green algaOstreococcus lucimarinuscan be modified to produce…
2015
Summary Biosynthesis of asymmetric carotenoids such as α-carotene and lutein in plants and green algae involves the two enzymes lycopene β-cyclase (LCYB) and lycopene e-cyclase (LCYE). The two cyclases are closely related and probably resulted from an ancient gene duplication. While in most plants investigated so far the two cyclases are encoded by separate genes, prasinophyte algae of the order Mamiellales contain a single gene encoding a fusion protein comprised of LCYB, LCYE and a C-terminal light-harvesting complex (LHC) domain. Here we show that the lycopene cyclase fusion protein from Ostreococcus lucimarinus catalyzed the simultaneous formation of α-carotene and β-carotene when heter…
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…
C172S Substitution in the Chloroplast-encoded Large Subunit Affects Stability and Stress-induced Turnover of Ribulose-1,5-bisphosphate Carboxylase/Ox…
1999
Previous work has indicated that the turnover of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1. 39) may be controlled by the redox state of certain cysteine residues. To test this hypothesis, directed mutagenesis and chloroplast transformation were employed to create a C172S substitution in the Rubisco large subunit of the green alga Chlamydomonas reinhardtii. The C172S mutant strain was not substantially different from the wild type with respect to growth rate, and the purified mutant enzyme had a normal circular dichroism spectrum. However, the mutant enzyme was inactivated faster than the wild-type enzyme at 40 and 50 degrees C. In contrast, C172S mutant …
Cysteines 449 and 459 modulate the reduction-oxidation conformational changes of ribulose 1.5-bisphosphate carboxylase/oxygenase and the translocatio…
2006
The role of cysteines 449 (Cys449) and 459 (Cys459) from the large subunit (LS) of ribulose 1-5-bisphosphate carboxylase/oxygenase (Rubisco) in the reduction-oxidation (redox) regulation of the enzyme was assessed by site-directed mutagenesis of these residues and chloroplast transformation of Chlamydomonas reinhardtii. In vitro studies indicated that mutations C449S, C459S or C449S/ C459S do not affect the activity and proteolytic susceptibility of the enzyme in the reduced state. However, when oxidized, the mutant enzymes differed from the wild type (WT), showing an increased resistance to inactivation and, in the case of the double mutant (DM), an altered structural conformation as refle…
Modification of the proteolytic fragmentation pattern upon oxidation of cysteines from ribulose 1,5-bisphosphate carboxylase/oxygenase.
2003
The proteolytic susceptibility of the native CO 2 -fixing photosynthetic enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39, Rubisco) has been shown to increase in vitro after oxidative treatments that affect cysteine thiols. A limited incubation of oxidized (pretreated with the disulfide cystamine) Rubisco from Chlamydomonas reinhardtii with subtilisin or proteinase K generated fragments of molecular mass about 53 kDa (band I in SDS-PAGE) and 47 kDa (band II) derived from the large subunit (55 kDa) of the enzyme. In contrast, proteolysis of the reduced Rubisco (pretreated with the free thiol cysteamine) produced only the 53 kDa band. The same fragmentation pattern was repr…
Quantum dots functionalised artificial peptides bioinspired to the D1 protein from the Photosystem II of Chlamydomonas reinhardtii for endocrine disr…
2021
Herein we describe the design and synthesis of novel artificial peptides mimicking the plastoquinone binding niche of the D1 protein from the green photosynthetic alga Chlamydomonas reinhardtii, also able to bind herbicides. In particular, molecular dynamics (MD) simulations were performed to model in silico the behaviour of three peptides, D1Pep70-H, D1Pep70-S264K and D1Pep70-S268C, as genetic variants with different affinity towards the photosynthetic herbicide atrazine. Then the photosynthetic peptides were functionalised with quantum dots for the development of a hybrid optosensor for the detection of atrazine, one of the most employed herbicides for weed control in agriculture as well …
Plant protein phosphorylation monitored by capillary liquid chromatography–element mass spectrometry
2007
Abstract Many essential cellular functions such as growth rate, motility, and metabolic activity are linked to reversible protein phosphorylation, since they are controlled by signaling cascades based mainly on phosphorylation/dephosphorylation events. Quantification of global or site-specific protein phosphorylation is not straightforward with standard proteomic techniques. The coupling of capillary liquid chromatography (μLC) with ICP-MS (inductively coupled plasma-mass spectrometry) is a method which allows a quantitative screening of protein extracts for their phosphorus and sulfur content, and thus provides access to the protein phosphorylation degree. In extension of a recent pilot st…
Compte rendu de : Johann Chapoutot, Libres d’obéir. Le management, du nazisme à aujourd’hui, Paris, Gallimard, 2020, 176 p.
2020
International audience