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1.
S. I. Allakhverdiev V. D. Kreslavski S. K. Zharmukhamedov R. A. Voloshin D. V. Korol’kova T. Tomo J.-R. Shen 《Biochemistry. Biokhimii?a》2016,81(3):201-212
The finding of unique Chl d- and Chl f-containing cyanobacteria in the last decade was a discovery in the area of biology of oxygenic photosynthetic organisms. Chl b, Chl c, and Chl f are considered to be accessory pigments found in antennae systems of photosynthetic organisms. They absorb energy and transfer it to the photosynthetic reaction center (RC), but do not participate in electron transport by the photosynthetic electron transport chain. However, Chl d as well as Chl a can operate not only in the light-harvesting complex, but also in the photosynthetic RC. The long-wavelength (Qy) Chl d and Chl f absorption band is shifted to longer wavelength (to 750 nm) compared to Chl a, which suggests the possibility for oxygenic photosynthesis in this spectral range. Such expansion of the photosynthetically active light range is important for the survival of cyanobacteria when the intensity of light not exceeding 700 nm is attenuated due to absorption by Chl a and other pigments. At the same time, energy storage efficiency in photosystem 2 for cyanobacteria containing Chl d and Chl f is not lower than that of cyanobacteria containing Chl a. Despite great interest in these unique chlorophylls, many questions related to functioning of such pigments in primary photosynthetic processes are still not elucidated. This review describes the latest advances in the field of Chl d and Chl f research and their role in primary photosynthetic processes of cyanobacteria. 相似文献
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L-Lactate cytochrome c oxidoreductase (flavocytochrome b 2, FC b 2) from the thermotolerant methylotrophic yeast Hansenula polymorpha (Pichia angusta) is, unlike the enzyme form baker’s yeast, a thermostable enzyme potentially important for bioanalytical technologies for highly selective assays of L-lactate in biological fluids and foods. This paper describes the construction of flavocytochrome b 2 producers with over-expression of the H. polymorpha CYB2 gene, encoding FC b 2. The HpCYB2 gene under the control of the strong H. polymorpha alcohol oxidase promoter in a plasmid for multicopy integration was transformed into the recipient strain H. polymorpha C-105 (grc1 catX), impaired in glucose repression and devoid of catalase activity. A method was developed for preliminary screening of the transformants with increased FC b 2 activity in permeabilized yeast cells. The optimal cultivation conditions providing for the maximal yield of the target enzyme were found. The constructed strain is a promising FC b 2 producer characterized by a sixfold increased (to 3 μmol min?1 mg?1 protein in cell-free extract) activity of the enzyme. 相似文献
3.
Lederer F 《European biophysics journal : EBJ》2011,40(12):1283-1299
Yeast flavocytochrome b 2 tranfers reducing equivalents from lactate to oxygen via cytochrome c and cytochrome c oxidase. The enzyme catalytic cycle includes FMN reduction by lactate and reoxidation by intramolecular electron transfer to heme b 2. Each subunit of the soluble tetrameric enzyme consists of an N terminal b 5-like heme-binding domain and a C terminal flavodehydrogenase. In the crystal structure, FMN and heme are face to face, and appear to be in a suitable orientation and at a suitable distance for exchanging electrons. But in one subunit out of two, the heme domain is disordered and invisible. This raises a central question: is this mobility required for interaction with the physiological acceptor cytochrome c, which only receives electrons from the heme and not from the FMN? The present review summarizes the results of the variety of methods used over the years that shed light on the interactions between the flavin and heme domains and between the enzyme and cytochrome c. The conclusion is that one should consider the interaction between the flavin and heme domains as a transient one, and that the cytochrome c and the flavin domain docking areas on the heme b 2 domain must overlap at least in part. The heme domain mobility is an essential component of the flavocytochrome b 2 functioning. In this respect, the enzyme bears similarity to a variety of redox enzyme systems, in particular those in which a cytochrome b 5-like domain is fused to proteins carrying other redox functions. 相似文献
4.
Kinetics of the reduction of the hemes in cytochrome c oxidase in the presence of high concentration of ruthenium(III)hexaammine chloride was examined using a stopped-flow spectrophotometer. Upon mixing of the oxidized enzyme with dithionite and Ru(NH3) 6 3+ , three well-resolved phases were observed: heme a reduction reaching completion within a few milliseconds is followed by two slow phases of heme a 3 reduction. The difference spectrum of heme a 3 reduction in the visible region is characterized by a maximum at ~612 nm, rather than at 603 nm as was believed earlier. It is shown that in the case of bovine heart cytochrome c oxidase containing a special cation-binding site in which reversible binding of calcium ion occurs, heme a 3 reduction is slowed down by low concentrations of Ca2+. The effect is absent in the case of the bacterial cytochrome oxidase in which the cation-binding site contains a tightly bound Ca2+ ion. The data corroborate the inhibition of the cytochrome oxidase enzymatic activity by Ca2+ ions discovered earlier and indicate that the cation affects intramolecular electron transfer. 相似文献
5.
Phaseolus vulgaris cv. Korona plants were inoculated with the bacteria Pseudomonas syringae pv. phaseolicola (Psp), necrotrophic fungus Botrytis cinerea (Bc) or with both pathogens sequentially. The aim of the experiment was to determine how plants cope with multiple infection with pathogens having different attack strategy. Possible suppression of the non-specific infection with the necrotrophic fungus Bc by earlier Psp inoculation was examined. Concentration of reactive oxygen species (ROS), such as superoxide anion (O2 ?) and H2O2 and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were determined 6, 12, 24 and 48 h after inoculation. The measurements were done for ROS cytosolic fraction and enzymatic cytosolic or apoplastic fraction. Infection with Psp caused significant increase in ROS levels since the beginning of experiment. Activity of the apoplastic enzymes also increased remarkably at the beginning of experiment in contrast to the cytosolic ones. Cytosolic SOD and guaiacol peroxidase (GPOD) activities achieved the maximum values 48 h after treatment. Additional forms of the examined enzymes after specific Psp infection were identified; however, they were not present after single Bc inoculation. Subsequent Bc infection resulted only in changes of H2O2 and SOD that occurred to be especially important during plant–pathogen interaction. Cultivar Korona of common bean is considered to be resistant to Psp and mobilises its system upon infection with these bacteria. We put forward a hypothesis that the extent of defence reaction was so great that subsequent infection did not trigger significant additional response. 相似文献
6.
The effect of supplementation of reduced glutathione (GSH) to cryoprotectant solution on the generation of reactive oxygen species (ROS) (e.g., H2O2, OH·, and O 2 ·? ) and antioxidants (e.g., SOD, POD, CAT, AsA, and GSH), as well as membrane lipid peroxidation (i.e., MDA content) mitigation in cryopreserving of embryogenic calli (EC) of Agapanthus praecox subsp. orientalis was investigated. The vitrification-based cryopreservation method was used in this study. The addition of GSH at a final concentration of 0.08 mM to the cryoprotectant solution has significantly improved cryotolerance of A. praecox EC. The EC post-thaw survival rate increased by 68.34 % using the cryoprotectant solution containing 0.08 mM GSH as compared to the control (GSH-free). EC treated with GSH displayed the reduction in OH· generation activity and the contents of H2O2 and MDA, as well as enhancement in the inhibition of O 2 ·? generation and the antioxidant activity. Treatment with exogenous GSH also increased endogenous AsA and GSH contents after dehydration step. Expression of stress-responsive genes, e.g., peroxidase (POD), peroxiredoxin, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and glutathione peroxidase (GPX), was also increased during cryopreservation processes. The expression of DAD1 (Defender against apoptotic cell death) was elevated, while cell death-related protease SBT was suppressed. These results demonstrated that the addition of GSH to cryoprotectant solution affects the ROS level and could effectively improve survival of A. praecox EC through enhancing antioxidant enzyme activities and decreasing cell death. 相似文献
7.
I. B. Kovalenko A. M. Abaturova P. A. Gromov D. M. Ustinin G. Yu. Riznichenko E. A. Grachev A. B. Rubin 《Biophysics》2008,53(2):140-146
Plastocyanin diffusion in the thylakoid lumen and its binding to cytochrome f (a subunit of the membrane b 6 f complex) were studied with a direct multiparticle simulation model that could also take account of their electrostatic interaction. Experimental data were used to estimate the model parameters for plastocyanin-cytochrome f complexing in solution. The model was then employed to assess the dependence of the association rate constant on the dimensions of the lumen. Highest rates were obtained at a lumen span of 8–10 nm; narrowing of the lumen below 7 nm resulted in drastic deceleration of complexing. This corresponded to the experimentally observed effect of hyperosmotic stress on the interaction between plastocyanin and cytochrome f in thylakoids. 相似文献
8.
Xue-Li Wan Jie Yang Xiao-Bai Li Qiao Zhou Cong Guo Man-Zhu Bao Jun-Wei Zhang 《Plant Molecular Biology Reporter》2016,34(5):899-908
Small heat shock proteins (sHSPs) have been shown to be involved in stress tolerance. However, their functions in Prunus mume under heat treatment are poorly characterized. To improve our understanding of sHSPs, we cloned a sHSP gene, PmHSP17.9, from P. mume. Sequence alignment and phylogenetic analysis indicated that PmHSP17.9 was a member of plant cytosolic class III sHSPs. Besides heat stress, PmHSP17.9 was also upregulated by salt, dehydration, oxidative stresses and ABA treatment. Leaves of transgenic Arabidopsis thaliana that ectopically express PmHSP17.9 accumulated less O2 ? and H2O2 compared with wild type (WT) after 42 °C treatment for 6 h. Over-expression of PmHSP17.9 in transgenic Arabidopsis enhanced seedling thermotolerance by decreased relative electrolyte leakage and MDA content under heat stress treatment when compared to WT plants. In addition, the induced expression of HSP101, HSFA2, and delta 1-pyrroline-5-carboxylate synthase (P5CS) under heat stress was more pronounced in transgenic plants than in WT plants. These results support the positive role of PmHSP17.9 in response to heat stress treatment. 相似文献
9.
Beibei Huang Xiaojun Liu Xinglong Wang Yan Pi Juan Lin Jiong Fei Xiaofen Sun Kexuan Tang 《Molecular Biology》2005,39(5):684-695
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Young-Saeng Kim Il-Sup Kim Joseph S. Boyd Arnaud Taton James W. Golden Ho-Sung Yoon 《Biotechnology letters》2017,39(10):1499-1507
Objectives
To improve the oxidative stress tolerance, biomass yield, and ascorbate/dehydroascorbate (AsA/DHA) ratio of Synechococcus elongatus PCC 7942 in the presence of H2O2, by heterologous expression of the dehydroascorbate reductase (DHAR) gene from Brassica juncea (BrDHAR).Results
Under H2O2 stress, overexpression of BrDHAR in the transgenic strain (BrD) of S. elongatus greatly increased the AsA/DHA ratio. As part of the AsA recycling system, the oxidative stress response induced by reactive oxygen species was enhanced, and intracellular H2O2 level decreased. In addition, under H2O2 stress conditions, the BrD strain displayed increased growth rate and biomass, as well as higher chlorophyll content and deeper pigmentation than did wild-type and control strains.Conclusion
By maintaining the AsA pool and redox homeostasis, the heterologous expression of BrDHAR increased S. elongatus tolerance to H2O2 stress, improving the biomass yield under these conditions. The results suggest that the BrD strain of S. elongatus, with its ability to attenuate the deleterious effects of ROS caused by environmental stressors, could be a promising platform for the generation of biofuels and other valuable bioproducts.14.
The goal of the study was to investigate the effects of exogenous selenium (Se) on the tolerance of faba bean plants to lead (Pb) stress under P-deficient conditions. The bean plants were grown for 2 weeks on Hoagland solution supplied with Pb (0, 50 μM) and Se (0, 1.5, or 6 μM), separately or simultaneously. It was shown that Pb did not affect shoot growth but caused major damage in the leaves, which was accompanied by Pb accumulation in these tissues. The exposure of the shoots to Pb led to significant changes in the biochemical parameters: the MDA content, glutathione peroxidase (GSH-Px), guaiacol peroxidase (GPOX), and catalase (CAT) activity increased. Furthermore, Pb intensified O 2 ?? and H2O2 production. Both the Se concentrations used increased the chlorophyll b, chlorophyll a+b, and carotenoid content in the faba bean plants. Selenite also generally enhanced CAT, GPOX, and GSH-Px activities and the T-SH level. Our results imply that the degree of disturbances caused by Pb could be partially ameliorated by Se supplementation. Selenite at a lower dose alleviated Pb toxicity by decreased H2O2 and O 2 ?? production and decreased the GSH-Px, GPOX, and CAT activities. The beneficial effect of the higher selenite concentration could be related to reduction of lipid peroxidation in the shoots of the Pb-treated plants. However, the effect of Se on the Pb-stressed plants greatly depended on the selenite dose in the nutrient solution. 相似文献
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Herman J. van Eck Peter G. Vos Jari P. T. Valkonen Jan G. A. M. L. Uitdewilligen Hellen Lensing Nick de Vetten Richard G. F. Visser 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(3):515-528
Key message
The method of graphical genotyping is applied to a panel of tetraploid potato cultivars to visualize haplotype sharing. The method allowed to map genes involved in virus and nematode resistance. The physical coordinates of the amount of linkage drag surrounding these genes are easily interpretable.Abstract
Graphical genotyping is a visually attractive and easily interpretable method to represent genetic marker data. In this paper, the method is extended from diploids to a panel of tetraploid potato cultivars. Application of filters to select a subset of SNPs allows one to visualize haplotype sharing between individuals that also share a specific locus. The method is illustrated with cultivars resistant to Potato virus Y (PVY), while simultaneously selecting for the absence of the SNPs in susceptible clones. SNP data will then merge into an image which displays the coordinates of a distal genomic region on the northern arm of chromosome 11 where a specific haplotype is introgressed from the wild potato species S. stoloniferum (CPC 2093) carrying a gene (Ny (o,n)sto ) conferring resistance to two PVY strains, PVYO and PVYNTN. Graphical genotyping was also successful in showing the haplotypes on chromosome 12 carrying Ry-f sto , another resistance gene derived from S. stoloniferum conferring broad-spectrum resistance to PVY, as well as chromosome 5 haplotypes from S. vernei, with the Gpa5 locus involved in resistance against Globodera pallida cyst nematodes. The image also shows shortening of linkage drag by meiotic recombination of the introgression segment in more recent breeding material. Identity-by-descent was found to be a requirement for using graphical genotyping, which is proposed as a non-statistical alternative method for gene discovery, as compared with genome-wide association studies. The potential and limitations of the method are discussed.17.
Arumugam Karthikeyan 《Symbiosis (Philadelphia, Pa.)》2017,72(2):89-94
Impact of different levels of elevated CO 2 on the activity of Frankia (Nitrogen-fixing actinomycete) in Casuarina equisetifolia rooted stem cuttings has been studied to understand the relationship between C. equisetifolia, Frankia and CO2. The stem cuttings of C. equietifolia were collected and treated with 2000 ppm of Indole Butyric Acid (IBA) for rooting. Thus vegetative propagated rooted stem cuttings of C. equisetifolia were inoculated with Frankia and placed in the Open top chambers (OTC) with elevated CO2 facilities. These planting stocks were maintained in the OTC for 12 months under different levels of elevated CO2 (ambient control, 600 ppm, 900 ppm). After 12 months, the nodule numbers, bio mass, growth, and photosynthesis of C. equisetifolia rooted stem cuttings inoculated with Frankia were improved under 600 ppm of CO2. The rooted stem cuttings of C. equisetifolia inoculated with Frankia showed a higher number of nodules under 900 ppm of CO2 and cuttings without Frankia inoculation exhibited poor growth. Tissue Nitrogen (N) content was also higher under 900 ppm of CO2 than ambient control and 600 ppm levels. The photosynthetic rate was higher (17.8 μ mol CO2 m?2 s?1) in 900 ppm of CO2 than in 600 ppm (13.2 μ mol CO2 m?2 s?1) and ambient control (8.3 μ mol CO2 m?2 s?1). This study showed that Frankia can improve growth, N fixation and photosynthesis of C. equietifolia rooted stem cuttings under extreme elevated CO2 level conditions (900 ppm). 相似文献
18.
L. R. Fayura D. V. Fedorovych T. M. Prokopiv Yu. R. Boretsky A. A. Sibirny 《Microbiology》2007,76(1):55-59
The yeast Pichia guilliermondii is capable of riboflavin overproduction under iron deficiency. The rib80, hit1, and red6 mutants of this species, which exhibit impaired riboflavin regulation, are also distinguished by increased iron concentrations in the cells and mitochondria, morphological changes in the mitochondria, as well as decreased growth rates (except for red6) and respiratory activity. With sufficient iron supply, the rib80 and red6 mutations cause a 1.5–1.8-fold decrease in the activity of such Fe-S cluster proteins as aconitase and flavocytochrome b 2, whereas the hit1 mutation causes a six-fold decrease. Under iron deficiency, the activity of these enzymes was equally low in all of the studied strains. 相似文献
19.
Liuqiang Wang Zhen Li Chao Wang Deyin Wang Yucheng Wang Mengzhu Lu 《Journal of Plant Biology》2017,60(6):548-557
Peroxiredoxins (Prxs) are ubiquitous thiol-specific antioxidant enzymes that are critically involved in cell defense and protect cells from oxidative damage. In this study, a putative Type II Prx (ThPrx1) was identified and characterized from Tamarix hispida. The expression of ThPrx1 is highly induced in response to hydrogen peroxide (H2O2) and methyl viologen (MV) stresses. When expressed ectopically, ThPrx1 showed enhanced tolerance against oxidative stress in yeast and Arabidopsis. In addition, transgenic Arabidopsis plants overexpressing ThPrx1 displayed improved seedling survival rates and increased root growth and fresh weight gain under H2O2 and MV treatments. Moreover, transgenic Arabidopsis plants showed decreased accumulation of H2O2, superoxide (O2??) and malondialdehyde (MDA), increased superoxide dismutase (SOD) activity compared to wild-type (WT) plants under oxidative stress. Moreover, transgenic plants maintained higher photosynthesis efficiency and lower electrolyte leakage rates than that of WT plants under stress conditions. These results clearly indicated that ThPrx1 plays an important role in cellular redox homeostasis under stress conditions, leading to the maintenance of membrane integrity and increased tolerance to oxidative stress. 相似文献
20.
Eukaryotic cells possess a special mechanism for the degradation of mRNAs containing premature termination codons (PTCs), referred to as NMD (nonsense-mediated mRNA decay). The strength of this pathway depends on the recognition of the PTCs by translational machinery and the interaction of translation termination factors eRF1 and eRF3 with Upf1, Upf2 and Upf3 proteins in Sachromyces cerevisiae yeast. Previously, we have shown that the decrease of eRF1 protein amounts in sup45 nonsense mutants leads to the impairment of NMD. Here we show that the deletion of UPF1 or UPF2 genes leads to an increase in the viability of sup45 mutants, while the effect of UPF3 gene deletion is allele-specific. Two-hybrid data have shown that amino acid residues 1–555 of Upf1 protein interact with eRF1. Any UPF gene deletion leads to allosupression of the adel1-14 mutation without a change in eRF1 content. The Upf1 depletion does not influence the synthetic lethality of sup45 mutations and the [PSI +] prion. It is possible that the absence of Upf1 (or its activator Upf2) leads to a more effective formation of the translation termination complex and consequently to the increased viability of the cells containing mutant termination factors. 相似文献