scholarly journals The chloroplast 2-cysteine peroxiredoxin functions as thioredoxin oxidase in redox regulation of chloroplast metabolism

2018 ◽  
Author(s):  
Mohamad-Javad Vaseghi ◽  
Kamel Chibani ◽  
Wilena Telman ◽  
Michael Liebthal ◽  
Melanie Gerken ◽  
...  
Keyword(s):  
Redox Regulation ◽  
Plant Cells ◽  
Decisive Role ◽  
Oxidative Inactivation ◽  
Fluctuating Light ◽  
Fructose 1,6 Bisphosphatase ◽  
Chloroplast Metabolism ◽  
Electron Sink ◽  
Kinetics Of

AbstractThiol-dependent redox regulation controls central processes in plant cells including photosynthesis. Thioredoxins reductively activate e.g. Calvin-Benson cycle enzymes. However the mechanism of oxidative inactivation is unknown despite its importance for efficient regulation. Here, the abundant 2-cysteine peroxiredoxin (2-CysPrx), but not its site-directed variants, mediates rapid inactivation of reductively activated fructose-1,6-bisphosphatase and NADPH-dependent malate dehydrogenase (MDH) in the presence of the proper thioredoxins. Deactivation of phosphoribulokinase and MDH was compromised in 2cysprxAB mutants plants upon light/dark transition compared to wildtype. The decisive role of 2cysprxAB in regulating photosynthesis was evident from reoxidation kinetics of ferredoxin upon darkening of intact leaves since its half time decreased 3.5-times in 2cysprxAB. The disadvantage of inefficient deactivation turned into an advantage in fluctuating light. The results show that the 2-CysPrx serves as electron sink in the thiol network important to oxidize reductively activated proteins and represents the missing link in the reversal of thioredoxin-dependent regulation.

scholarly journals The chloroplast 2-cysteine peroxiredoxin functions as thioredoxin oxidase in redox regulation of chloroplast metabolism

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Mohamad-Javad Vaseghi ◽  
Kamel Chibani ◽  
Wilena Telman ◽  
Michael Florian Liebthal ◽  
Melanie Gerken ◽  
...  
Keyword(s):  
Redox Regulation ◽  
Plant Cells ◽  
Decisive Role ◽  
Oxidative Inactivation ◽  
Fluctuating Light ◽  
Fructose 1,6 Bisphosphatase ◽  
Chloroplast Metabolism ◽  
Electron Sink ◽  
Kinetics Of

Thiol-dependent redox regulation controls central processes in plant cells including photosynthesis. Thioredoxins reductively activate, for example, Calvin-Benson cycle enzymes. However, the mechanism of oxidative inactivation is unknown despite its importance for efficient regulation. Here, the abundant 2-cysteine peroxiredoxin (2-CysPrx), but not its site-directed variants, mediates rapid inactivation of reductively activated fructose-1,6-bisphosphatase and NADPH-dependent malate dehydrogenase (MDH) in the presence of the proper thioredoxins. Deactivation of phosphoribulokinase (PRK) and MDH was compromised in 2cysprxAB mutant plants upon light/dark transition compared to wildtype. The decisive role of 2-CysPrx in regulating photosynthesis was evident from reoxidation kinetics of ferredoxin upon darkening of intact leaves since its half time decreased 3.5-times in 2cysprxAB. The disadvantage of inefficient deactivation turned into an advantage in fluctuating light. Physiological parameters like MDH and PRK inactivation, photosynthetic kinetics and response to fluctuating light fully recovered in 2cysprxAB mutants complemented with 2-CysPrxA underlining the significance of 2-CysPrx. The results show that the 2-CysPrx serves as electron sink in the thiol network important to oxidize reductively activated proteins and represents the missing link in the reversal of thioredoxin-dependent regulation.

Thioredoxin-like2/2-Cys peroxiredoxin redox cascade acts as oxidative activator of glucose-6-phosphate dehydrogenase in chloroplasts

2019 ◽  
Vol 476 (12) ◽  
pp. 1781-1790 ◽  
Author(s):  
Keisuke Yoshida ◽  
Eriko Uchikoshi ◽  
Satoshi Hara ◽  
Toru Hisabori
Keyword(s):  
Redox Regulation ◽  
Pentose Phosphate ◽  
Activation Mechanism ◽  
Protein Activation ◽  
Fluctuating Light ◽  
State Determination ◽  
Chloroplast Metabolism ◽  
Oxidative Activation ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Novel Protein

Abstract Thiol-based redox regulation is crucial for adjusting chloroplast functions under fluctuating light environments. We recently discovered that the thioredoxin-like2 (TrxL2)/2-Cys peroxiredoxin (2CP) redox cascade supports oxidative thiol modulation by using hydrogen peroxide (H2O2) as an oxidizing force. This system plays a key role in switching chloroplast metabolism (e.g. Calvin–Benson cycle) during light to dark transitions; however, information on its function is still limited. In this study, we report a novel protein-activation mechanism based on the TrxL2/2CP redox cascade. Glucose-6-phosphate dehydrogenase (G6PDH) catalyzes the first step of the oxidative pentose phosphate pathway (OPPP). Biochemical studies, including redox state determination and measurement of enzyme activity, suggested that the TrxL2/2CP pathway is involved in the oxidative activation of G6PDH. It is thus likely that the TrxL2/2CP redox cascade shifts chloroplast metabolism to night mode by playing a dual role, namely, down-regulation of the Calvin–Benson cycle and up-regulation of OPPP. G6PDH was also directly oxidized and activated by H2O2, particularly when H2O2 concentration was elevated. Therefore, G6PDH is thought to be finely tuned by H2O2 levels in both direct and indirect manners.

Nuclear Radiation Detection Scintillators based on ZnSe(Te) crystals.

2011 ◽  
Vol 1341 ◽  
Author(s):  
Volodymyr D. Ryzhikov
Keyword(s):  
Solid Phase ◽  
Radiation Detection ◽  
Decisive Role ◽  
Nuclear Radiation ◽  
Energy Devices ◽  
Preparation Conditions ◽  
Radiation Spectra ◽  
Scintillation Crystals ◽  
Kinetics Of

ABSTRACTWe describe development of semiconductor scintillators (SCS) on the basis of AIIBVI compounds has bridged the gap in a series of “scintillator-photodiode” detectors used in modern multi-channel low-energy devices for visualization of hidden images (tomographs, introscopes). In accordance with the requirements of eventual applications, such SCS materials as ZnSe(Te) show the best matching of intrinsic radiation spectra to photosensitivity spectra of silicon photodiodes (PD) among the materials of similar kind. They are characterized by high radiation and thermal stability of their output parameters, as well as by high conversion efficiency. In this work, a thermodynamic model is described for interaction of isovalent dopants (IVD) with intrinsic point defects of AIIBVI semiconductor structures at different ratios of their charges, a decisive role of IVD is shown in formation of the luminescence centers, kinetics of solid-phase reactions and the role of a gas medium are considered under real preparation conditions of ZnSe(Te) scintillation crystals, and luminescence mechanisms in IVD-doped SCS are discussed.

scholarly journals Autophagy Is Involved in the Viability of Overexpressing Thioredoxin o1 Tobacco BY-2 Cells under Oxidative Conditions

Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1884
Author(s):  
Sabrina De Brasi-Velasco ◽  
Omar López-Vidal ◽  
María Carmen Martí ◽  
Ana Ortiz-Espín ◽  
Francisca Sevilla ◽  
...  
Keyword(s):  
Gene Expression ◽  
Redox Regulation ◽  
Plant Cells ◽  
Dot Blot ◽  
Functional Interaction ◽  
H2o2 Treatment ◽  
Useful Components ◽  
In Vitro Interaction

Autophagy is an essential process for the degradation of non-useful components, although the mechanism involved in its regulation is less known in plants than in animal systems. Redox regulation of autophagy components is emerging as a possible key mechanism with thioredoxins (TRXs) proposed as involved candidates. In this work, using overexpressing PsTRXo1 tobacco cells (OEX), which present higher viability than non-overexpressing cells after H2O2 treatment, we examine the functional interaction of autophagy and PsTRXo1 in a collaborative response. OEX cells present higher gene expression of the ATG (Autophagy related) marker ATG4 and higher protein content of ATG4, ATG8, and lipidated ATG8 as well as higher ATG4 activity than control cells, supporting the involvement of autophagy in their response to H2O2. In this oxidative situation, autophagy occurs in OEX cells as is evident from an accumulation of autolysosomes and ATG8 immunolocalization when the E-64d autophagy inhibitor is used. Interestingly, cell viability decreases in the presence of the inhibitor, pointing to autophagy as being involved in cell survival. The in vitro interaction of ATG4 and PsTRXo1 proteins is confirmed by dot-blot and co-immunoprecipitation assays as well as the redox regulation of ATG4 activity by PsTRXo1. These findings extend the role of TRXs in mediating the redox regulation of the autophagy process in plant cells.

Redox signals as a language of interorganellar communication in plant cells

2013 ◽  
Vol 8 (12) ◽  
pp. 1153-1163 ◽  
Author(s):  
Tomasz Kopczewski ◽  
Elżbieta Kuźniak
Keyword(s):  
Redox Regulation ◽  
Biological Effects ◽  
Physiological Responses ◽  
Plant Cells ◽  
Enzymatic Antioxidants ◽  
Oxygen Species ◽  
Redox Systems ◽  
Disulfide Exchange ◽  
Redox Active

AbstractPlants are redox systems and redox-active compounds control and regulate all aspects of their life. Recent studies have shown that changes in reactive oxygen species (ROS) concentration mediated by enzymatic and non-enzymatic antioxidants are transferred into redox signals used by plants to activate various physiological responses. An overview of the main antioxidants and redox signaling in plant cells is presented. In this review, the biological effects of ROS and related redox signals are discussed in the context of acclimation to changing environmental conditions. Special attention is paid to the role of thiol/disulfide exchange via thioredoxins (Trxs), glutaredoxins (Grxs) and peroxiredoxins (Prxs) in the redox regulatory network. In plants, chloroplasts and mitochondria occupying a chloroplasts and mitochondria play key roles in cellular metabolism as well as in redox regulation and signaling. The integrated redox functions of these organelles are discussed with emphasis on the importance of the chloroplast and mitochondrion to the nucleus retrograde signaling in acclimatory and stress response.

Activation of cytochrome c to a peroxidase compound I-type intermediate by H2O2: relevance to redox signalling in apoptosis

2004 ◽  
Vol 71 ◽  
pp. 97-106 ◽  
Author(s):  
Mark Burkitt ◽  
Clare Jones ◽  
Andrew Lawrence ◽  
Peter Wardman
Keyword(s):  
Cytochrome C ◽  
Hydroxyl Radical ◽  
Redox Regulation ◽  
Chemotherapeutic Agents ◽  
Tyrosyl Radical ◽  
Compound I ◽  
Definitive Evidence ◽  
Enhanced Production ◽  
Physico Chemical

The release of cytochrome c from mitochondria during apoptosis results in the enhanced production of superoxide radicals, which are converted to H2O2 by Mn-superoxide dismutase. We have been concerned with the role of cytochrome c/H2O2 in the induction of oxidative stress during apoptosis. Our initial studies showed that cytochrome c is a potent catalyst of 2′,7′-dichlorofluorescin oxidation, thereby explaining the increased rate of production of the fluorophore 2′,7′-dichlorofluorescein in apoptotic cells. Although it has been speculated that the oxidizing species may be a ferryl-haem intermediate, no definitive evidence for the formation of such a species has been reported. Alternatively, it is possible that the hydroxyl radical may be generated, as seen in the reaction of certain iron chelates with H2O2. By examining the effects of radical scavengers on 2′,7′-dichlorofluorescin oxidation by cytochrome c/H2O2, together with complementary EPR studies, we have demonstrated that the hydroxyl radical is not generated. Our findings point, instead, to the formation of a peroxidase compound I species, with one oxidizing equivalent present as an oxo-ferryl haem intermediate and the other as the tyrosyl radical identified by Barr and colleagues [Barr, Gunther, Deterding, Tomer and Mason (1996) J. Biol. Chem. 271, 15498-15503]. Studies with spin traps indicated that the oxo-ferryl haem is the active oxidant. These findings provide a physico-chemical basis for the redox changes that occur during apoptosis. Excessive changes (possibly catalysed by cytochrome c) may have implications for the redox regulation of cell death, including the sensitivity of tumour cells to chemotherapeutic agents.

The main directions of educational policy of Finland

2020 ◽  
Vol 11 (2) ◽  
pp. 6-13
Author(s):  
K. E. Stupak ◽  
Keyword(s):  
Higher Education ◽  
Education Policy ◽  
Education System ◽  
Decisive Role ◽  
The State ◽  
Vocational Education And Training ◽  
State Education Policy ◽  
Role Of The State ◽  
State Education

The article deals with analyzing the main streams of the education policy in Finland, which reflect the relationship between a person and society in modern socio–economic conditions. Such policy directs the system of education to change the person and his mind himself. Finland using its education system, has long before been concerned about preparing people for the future by reforming approaches to teaching in schools and higher education institutions. As a result, it has achieved world–wide recognition and top positions in various ratings have resulted. Therefore, today there is a great interest of scientists in certain issues of education functioning in Finland. Thus, G. Androshchuk, V. Butova. I. Zhernokleeva, T. Pushkareva and others study in their works the purpose and decisive role of Finland's education policy in the development of the education system. S. Grinyuk and V. Zagvozdkin pay attention to the practical the steps of reforming the Finnish system of education. T. Drobyshevsk investigates the system of providing educational services in Finland as a sector of knowledge production. L. Volynets, P. Kukharchuk consider the principles of the state education policy of Finland. L. Smolskaya examines the role of the state policy in implementing the "Finnish phenomenon"; P. Basyliuk and Yu. Kulykova, focus attention on the study of the evolution of the system of higher education in Finland; O. Scherbak reveals peculiarities of vocational education and training.

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