oxygen evolution
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Aryloxyaminopropanoly (AOAP) inhibujú rýchlosť vývoja kyslíka v chloroplastoch špenátu. Inhibičná aktivita AOAP narastá predlžovaním alkylového reťazca v esterickej časti molekuly. 3-substituované deriváty vykazujú výraznejšiu inhibičnú aktivitu než deriváty substituované v polohe 2 a 4. Z uvedených výsledkov možno predpokladať, že AOAP majú dve aktívne centrá schopné interakcie s tylakoidnou membránou chloroplastov, pričom priestorové parametre efektora budú z hľadiska tejto interakcie najvýhodnejšie v prípade 3-substituovaných AOAP. Rozvetvenie alkylsubstitúcie v esterickej časti molekuly má za následok zníženie inhibičnej aktivity.
Aryloxyaminopropanols (AOAP) inhibit oxygen evolution rate in spinach chloroplasts. The inhibitory activity of AOAP increases with the increasing alkyl chain length in the esteric group of the AOAP molecule. 3-substituted derivatives show a pronouncedly higher inhibitory activity than the 2- and 4-substituted ones. Thus, it can be assumed that AOAP have two active parts which are able to interact with the thylakoid membranes of chloroplasts, whereby the most effective space parameters are reached with 3-alkoxy-substituted AOAP. The branching of the alkyl substituent in the esteric part of the molecule leads to a decrease in the inhibitory activity.
The light-driven splitting of water to oxygen (O2) is catalyzed by a protein-bound tetra-manganese penta-oxygen calcium (Mn4O5Ca) cluster in Photosystem II. In the current study, we used a large-scale integration (LSI)-based amperometric sensor array system, designated Bio-LSI, to perform two-dimensional imaging of light-induced O2 evolution from spinach leaves. The employed Bio-LSI chip consists of 400 sensor electrodes with a pitch of 250 μm for fast electrochemical imaging. Spinach leaves were illuminated to varying intensities of white light (400-700 nm) which induced oxygen evolution and subsequent electrochemical images were collected using the Bio-LSI chip. Bio-LSI images clearly showed the dose-dependent effects of the light-induced oxygen release from spinach leaves which was then significantly suppressed in the presence of urea-type herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Our results clearly suggest that light-induced oxygen evolution can be monitored using the chip and suggesting that the Bio-LSI is a promising tool for real-time imaging. To the best of our knowledge, this report is the first to describe electrochemical imaging of light-induced O2 evolution using LSI-based amperometric sensors in plants.
An emerging class of novel heme-based oxygen sensors containing a globin fold binds and senses environmental O2 via a heme iron complex. Structure-function relationships of oxygen sensors containing a heme-bound globin fold are different from those containing heme-bound PAS and GAF folds. It is thus worth reconsidering from an evolutionary perspective how heme-bound proteins with a globin fold similar to that of hemoglobin and myoglobin could act as O2 sensors. Here, we summarize the molecular mechanisms of heme-based oxygen sensors containing a globin fold in an effort to shed light on the O2-sensing properties and O2-stimulated catalytic enhancement observed for these proteins.
- MeSH
- Azotobacter vinelandii enzymologie MeSH
- Bordetella pertussis enzymologie MeSH
- chemotaxe MeSH
- Escherichia coli enzymologie MeSH
- globiny chemie MeSH
- hem chemie MeSH
- hemoglobiny chemie MeSH
- katalytická doména MeSH
- katalýza MeSH
- kyslík chemie MeSH
- lyasy štěpící vazby P-O chemie MeSH
- molekulární evoluce MeSH
- molekulární sekvence - údaje MeSH
- myoglobin chemie MeSH
- proteinkinasy chemie MeSH
- proteiny z Escherichia coli chemie MeSH
- regulace genové exprese enzymů * MeSH
- sekvence aminokyselin MeSH
- sekvenční homologie aminokyselin MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Lateral gene transfer (LGT) is an important mechanism of evolution for protists adapting to oxygen-poor environments. Specifically, modifications of energy metabolism in anaerobic forms of mitochondria (e.g., hydrogenosomes) are likely to have been associated with gene transfer from prokaryotes. An interesting question is whether the products of transferred genes were directly targeted into the ancestral organelle or initially operated in the cytosol and subsequently acquired organelle-targeting sequences. Here, we identified key enzymes of hydrogenosomal metabolism in the free-living anaerobic amoebozoan Mastigamoeba balamuthi and analyzed their cellular localizations, enzymatic activities, and evolutionary histories. Additionally, we characterized 1) several canonical mitochondrial components including respiratory complex II and the glycine cleavage system, 2) enzymes associated with anaerobic energy metabolism, including an unusual D-lactate dehydrogenase and acetyl CoA synthase, and 3) a sulfate activation pathway. Intriguingly, components of anaerobic energy metabolism are present in at least two gene copies. For each component, one copy possesses an mitochondrial targeting sequence (MTS), whereas the other lacks an MTS, yielding parallel cytosolic and hydrogenosomal extended glycolysis pathways. Experimentally, we confirmed that the organelle targeting of several proteins is fully dependent on the MTS. Phylogenetic analysis of all extended glycolysis components suggested that these components were acquired by LGT. We propose that the transformation from an ancestral organelle to a hydrogenosome in the M. balamuthi lineage involved the lateral acquisition of genes encoding extended glycolysis enzymes that initially operated in the cytosol and that established a parallel hydrogenosomal pathway after gene duplication and MTS acquisition.
- MeSH
- anaerobióza genetika MeSH
- Archamoebae enzymologie genetika metabolismus MeSH
- duplikace genu * MeSH
- energetický metabolismus genetika MeSH
- enzymy genetika izolace a purifikace MeSH
- molekulární evoluce * MeSH
- organely enzymologie genetika metabolismus MeSH
- přenos genů horizontální * MeSH
- struktury buněčné membrány genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Magnesium-protoporphyrin IX monomethylester cyclase is one of the key enzymes of the bacteriochlorophyll biosynthesis pathway. There exist two fundamentally different forms of this enzyme. The oxygen-dependent form, encoded by the gene acsF, catalyzes the formation of the bacteriochlorophyll fifth ring using oxygen, whereas the oxygen-independent form encoded by the gene bchE utilizes an oxygen atom extracted from water. The presence of acsF and bchE genes was surveyed in various phototrophic Proteobacteria using the available genomic data and newly designed degenerated primers. It was found that while the majority of purple nonsulfur bacteria contained both forms of the cyclase, the purple sulfur bacteria contained only the oxygen-independent form. All tested species of aerobic anoxygenic phototrophs contained acsF genes, but some of them also retained the bchE gene. In contrast to bchE phylogeny, the acsF phylogeny was in good agreement with 16S inferred phylogeny. Moreover, the survey of the genome data documented that the acsF gene occupies a conserved position inside the photosynthesis gene cluster, whereas the bchE location in the genome varied largely between the species. This suggests that the oxygen-dependent cyclase was recruited by purple phototrophic bacteria very early during their evolution. The primary sequence and immunochemical similarity with its cyanobacterial counterparts suggests that acsF may have been acquired by Proteobacteria via horizontal gene transfer from cyanobacteria. The acquisition of the gene allowed purple nonsulfur phototrophic bacteria to proliferate in the mildly oxygenated conditions of the Proterozoic era.
- MeSH
- bakteriální proteiny analýza chemie genetika MeSH
- fotosyntéza genetika MeSH
- fylogeneze MeSH
- genom bakteriální MeSH
- kyslík metabolismus MeSH
- oxygenasy analýza chemie genetika MeSH
- protein - isoformy analýza chemie genetika MeSH
- Proteobacteria enzymologie genetika metabolismus MeSH
- sinice enzymologie genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Many animals use carotenoid pigments to produce yellow, orange, and red coloration. In birds, at least 10 carotenoid compounds have been documented in red feathers; most of these are produced through metabolic modification of dietary precursor compounds. However, it is poorly understood how lineages have evolved the biochemical mechanisms for producing red coloration. We used high-performance liquid chromatography to identify the carotenoid compounds present in feathers from 15 species across two clades of blackbirds (the meadowlarks and allies, and the caciques and oropendolas; Icteridae), and mapped their presence or absence on a phylogeny. We found that the red plumage found in meadowlarks includes different carotenoid compounds than the red plumage found in caciques, indicating that these gains of red color are convergent. In contrast, we found that red coloration in two closely related lineages of caciques evolved twice by what appear to be similar biochemical mechanisms. The C4-oxygenation of dietary carotenoids was responsible for each observed transition from yellow to red plumage coloration, and has been commonly reported by other researchers. This suggests that the C4-oxygenation pathway may be a readily evolvable means to gain red coloration using carotenoids.
- MeSH
- fylogeneze MeSH
- karotenoidy genetika metabolismus MeSH
- molekulární evoluce * MeSH
- oxidace-redukce MeSH
- peří anatomie a histologie MeSH
- pigmentace genetika MeSH
- zpěvní ptáci anatomie a histologie klasifikace genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
