Role Of Electron Transport Chain Research Articles

Dual Mode of Mitochondrial ROS Action during Reprogramming to Pluripotency.

Essential changes in cell metabolism and redox signaling occur during the reprogramming of somatic cells into induced pluripotent stem cells (iPSCs). In this paper, using genetic and pharmacological approaches, we have investigated the role of electron transport chain (ETC) complex-I (CI) of mitochondria in the process of cell reprogramming to pluripotency. Knockdown of NADH-ubiquinone oxidoreductase core subunits S1 (Ndufs1) or subunit B10 (Ndufb10) of the CI or inhibition of this complex with rotenone during mouse embryonic fibroblast (MEF) reprogramming resulted in a significantly decreased number of induced pluripotent stem cells (iPSCs). We have found that mitochondria and ROS levels due course of the reprogramming tightly correlate with each other, both reaching peak by day 3 and significantly declining by day 10 of the process. The transient augmentation of mitochondrial reactive oxygen species (ROS) could be attenuated by antioxidant treatment, which ameliorated overall reprogramming. However, ROS scavenging after day 3 or during the entire course of reprogramming was suppressive for iPSC formation. The ROS scavenging within the CI-deficient iPSC-precursors did not improve, but further suppressed the reprogramming. Our data therefore point to distinct modes of mitochondrial ROS action during the early versus mid and late stages of reprogramming. The data further substantiate the paradigm that balanced levels of oxidative phosphorylation have to be maintained on the route to pluripotency.

Process, Outcomes and Possible Elimination of Aggregation with Special Reference to Heme Proteins; Likely Remediations of Proteinopathies.

Protein folding is a natural phenomenon through which a linear polypeptide possessing necessary information attains three-dimension functionally active conformation. This is a complex and multistep process and therefore, the presence of several intermediary structures could be speculated as a result of protein folding. In in vivo, this folding process is governed by the assistance of other proteins called molecular chaperones and heat shock proteins. Due to the mechanism of protein folding, these intermediary structures remain major challenge for modern biology. Mutation in gene encoding amino acid can cause adverse environmental conditions which may result in misfolding of the linear polypeptide followed by the formation of aggregates and amyloidosis. Aggregation contributes to the pathophysiology of several maladies including diabetes mellitus, Huntington's and Alzheimer's disease. The propensity of native structure to form aggregated and fibrillar assemblies is a hallmark of amyloidosis. During aggregation of a protein, transition from α helix to β sheet is observed, and mainly β sheeted structure is visualised in a mature fibril. Heme proteins are very crucial for major life activities like transport of oxygen and carbon dioxide, synthesis of ATP, role in electron transport chain, and detoxification of free radicals formed during biochemical reactions. Any structural variation in the heme proteins may lead to a fatal response. Hence characterization of the folding intermediates becomes crucial. The characterization has been deciphered with the help of strong denaturants like acetonitrile and TFE. Moreover, possible role of elimination of these aggregates and prevention of protein denaturation is also discussed. Current review deals with the basic process and mechanism of the protein folding in general and the ultimate outcomes of the protein misfolding. Since Native conformation of heme proteins is essential for some vital activities as listed above, we have discussed possible prevention of denaturation and aggregation of heme proteins such as Hb, cyt c, catalase & peroxidase.

Inhibition of the electron transport chain in propofol induced neurotoxicity in zebrafish embryos

Fetal and neonatal exposure to propofol can lead to neuronal death and long-term neurobehavioral deficiencies in both rodents and nonhuman primates. Zebrafish embryo, which is fertilized ex-utero, has provided us a new model species to study the effects of general anesthetics on developing brain. Inhibited electron transport chain leads to mitochondrial dysfunction and insufficient energy production. The aim of this study was to dissect the role of electron transport chain in propofol-induced neurotoxicity. 6 h post fertilization (hpf) zebrafish embryos were exposed to control or 1, 2 or 4 μg/ml propofol until 48hpf. Acridine orange staining was used to assess cell apoptosis in the brain of zebrafish embryos. The activity of mitochondrial electron transport chain complex was assessed using colorimetric method. Expression of key subunit of cytochrome c oxidase was assessed by western blot and transcription level of cox4i1 was assessed by quantitative real time-PCR. The mitochondrial membrane potential and ATP content were assessed. Exposure to 1, 2 and 4 μg/ml propofol induced significant increases in cell apoptosis in the brain of zebrafish embryos in a dose-dependent manner and led to significant decreases in electron transport chain complex IV activity from (0.161 ± 0.023)μmol/mg/min in blank control-treated group to (0.096 ± 0.015)μmol/mg/min, (0.083 ± 0.013)μmol/mg/min and (0.045 ± 0.014)μmol/mg/min respectively, accompanied by decreased expression of key regulatory subunit of cytochrome c oxidase-subunit IV and decreased transcription level of cox4i1. Propofol exposure also decreased the mitochondrial membrane potential and ATP content. Our findings demonstrate that inhibition of the electron transport chain is involved in the mechanisms by which propofol induces neurotoxicity in the developing brain.

Biochar remediates denitrification process and N2O emission in pesticide chlorothalonil-polluted soil: Role of electron transport chain

Agricultural production causes large amounts of pesticide residues into soil, disturbing soil denitrification and N2O emission. Recently, biochar amendment has been regarded as the effective way to stimulate soil denitrification and reduce N2O emission. However, the underlying mechanism has not been well understood. Here, the effects of biochar on denitrification and N2O emission in the chlorothalonil (CHT)-polluted soil were explored. Biochar (50 g kg−1) was added to soil at the beginning of the experiment, and CHT (5 and 25 mg kg−1) was repeatedly applied to soil at the 30-day interval for 105 days. The obtained results showed that CHT remarkably declined soil respiration rates (52–77%) and denitrification rates (50–56%), but increased N2O emissions by 820–1030%. After biochar application, however, soil denitrification rates were increased by 13–26%, and N2O emissions were declined by 442–809% compared with non-biochar spiked soils. A further mechanism study indicated that biochar remarkably promoted the activities of microbial electron transfer chain, electron transporters (complex I, II, III and cytochrome c), and four denitrifying reductases (NAR, NIR, NOR, NOS) in CHT-polluted soils, suggesting that electron transport and consumption capacities during denitrification were stimulated by biochar. Soil denitrification was thus improved and N2O emission was subsequently reduced. Furthermore, biochar significantly upregulated soil denitrifying gene abundances and increased denitrifiers abundances (i.e., Enterobacter and Pseudarthrobacter). Overall, this work will promote the current understandings of molecular mechanisms through which N2O emission in pesticide contaminated soils responds to biochar remediation.

Molecular Modeling and Docking Analysis Of Callosobruchus maculates Cytochrome B Proteins with Bio Active Compound Phytolfrom Glinus lotoides and Synthetic Pesticide Pirimiphos-Methyl

Cytochrome b is a component of respiratory chain complex III, also known as bc1 complex or ubiquinol-cytochrome c reductase. These complexes are involved in electron transport and generation of ATP and thus play a vital role in electron transport chain. Phytol is a phytochemical derived from ethyl acetate extract of Glinus lotoides. Cytochrome b modeled and the structure was used for In-silico binding efficiency and comparative analysis of cytochrome b with Phytol and synthetic pesticide were showed good docking score and binding affinity when compared to control. This study will be used in broad screening of the protein in the respiratory process and can be further implemented in designing pest control.

Role of electron transport chain of chloroplasts in oxidative burst of interaction between Erwinia amylovora and host cells.

Erwinia amylovora is a necrogenic bacterium, causing the fire blight disease on many rosaceous plants. Triggering oxidative burst by E. amylovora is a key response by which host plants try to restrain pathogen spread. Electron transport chain (ETC) of chloroplasts is known as an inducible source of reactive oxygen species generation in various stresses. This research was performed to assess the role of this ETC in E. amylovora-host interaction using several inhibitors of this chain in susceptible and resistant apple and pear genotypes. All ETC inhibitors delayed appearance of disease necrosis, but the effects of methyl viologen, glutaraldehyde, and DCMU were more significant. In the absence of inhibitors, resistant genotypes showed an earlier and severe H2O2 generation and early suppression of redox dependent, psbA gene. The effects of inhibitors were corresponding to the redox potential of ETC inhibitory sites. In addition, delayed necrosis appearance was associated with the decreased disease severity and delayed H2O2 generation. These results provide evidences for the involvement of this ETC in host oxidative burst and suggest that chloroplast ETC has significant role in E. amylovora-host interaction.

Enhanced photo-electrochemical performances of graphene-based composite functionalized by Zn2+ tetraphenylporphyrin

Inspired by the role of electron transport chain in chlorophyll, graphene (G) complexation with zinc 5, 10, 15, 20-tetraphenylporphyrin (ZnTPP) is expected to have excellent photo-electrochemical performances. Here, we design a facile strategy to synthesize the functionalized graphene/zinc tetraphenylporphyrin (G/ZnTPP) composite. In which, all characterizations indicate synergistic effect does exist between graphene sheets and ZnTPP. The synergistic effect enables such composite to possess improved photo-electrochemical behaviors that are key features for photoelectric conversion device. On the basis of this, attempts to modify the absorption range, improve specific capacitance and lower resistance to acquire effective photo-current responses have been successfully demonstrated in this research.

Mitochondrial genome regulates mitotic fidelity by maintaining centrosomal homeostasis

Centrosomes direct spindle morphogenesis to assemble a bipolar mitotic apparatus to enable error-free chromosome segregation and preclude chromosomal instability (CIN). Amplified centrosomes, a hallmark of cancer cells, set the stage for CIN, which underlies malignant transformation and evolution of aggressive phenotypes. Several studies report CIN and a tumorigenic and/or aggressive transformation in mitochondrial DNA (mtDNA)-depleted cells. Although several nuclear-encoded proteins are implicated in centrosome duplication and spindle organization, the involvement of mtDNA encoded proteins in centrosome amplification (CA) remains elusive. Here we show that disruption of mitochondrial function by depletion of mtDNA induces robust CA and mitotic aberrations in osteosarcoma cells. We found that overexpression of Aurora A, Polo-like kinase 4 (PLK4), and Cyclin E was associated with emergence of amplified centrosomes. Supernumerary centrosomes in rho0 (mtDNA-depleted) cells resulted in multipolar mitoses bearing “real” centrosomes with paired centrioles at the multiple poles. This abnormal phenotype was recapitulated by inhibition of respiratory complex I in parental cells, suggesting a role for electron transport chain (ETC) in maintaining numeral centrosomal homeostasis. Furthermore, rho0 cells displayed a decreased proliferative capacity owing to a G2/M arrest. Downregulation of nuclear-encoded p53 in rho0 cells underscores the importance of mitochondrial and nuclear genome crosstalk and may perhaps underlie the observed mitotic aberrations. By contrast, repletion of wild-type mtDNA in rho0 cells (cybrid) demonstrated a much lesser extent of CA and spindle multipolarity, suggesting partial restoration of centrosomal homeostasis. Our study provides compelling evidence to implicate the role of mitochondria in regulation of centrosome duplication, spindle architecture, and spindle pole integrity.

Azo dye load-shock on relative behavior of biofilm and suspended growth configured periodic discontinuous batch mode operations: Critical evaluation with enzymatic and bio-electrocatalytic analysis

Effect of dye (C.I.Acid Black 10B) load-shock was comparatively evaluated in biofilm (self-immobilized) and suspended growth systems operated in periodic discontinuous batch mode (PDBR, anoxic-aerobic-anoxic) was investigated. At higher dye load (1250 mg dye/l), biofilm system showed relatively higher dye (74.5%) and COD (46%) removal efficiencies than the corresponding suspended mode operation (dye/COD removal efficiency, 42%/65%). Increment in dye load showed increment in azo reductase and dehydrogenase enzyme activities. Voltammograms (cyclic) showed higher reduction currents (RC) with increment in dye load specifically in biofilm system. Derivative cyclic voltammograms analysis depicted the involvement of mediators (NAD +, FAD+, etc.) which presumably played a major role in electron transport chain and dye degradation. Disappearance of peak (1612 cm−1) specific to azo group in FTIR spectrum, at higher loading rate in both the systems indicates the non-inhibitory and robust nature of PDBR operation.

Prediction of Evolutionarily important catalytic amino acid of Mycobacterium tuberculosis O-Succinylbenzoate synthase through in silico mutational analysis

AbstractThe emergence of tuberculosis resistant to multiple, first- and second-line antibiotics poses challenges to a global control strategy that relies on standard drug treatment regimens. The high drug-resistant strains of Mycobacterium tuberculosis (Mtb) have been implicated in outbreaks and have been found throughout the world; a comprehensive understanding, the magnitude of this threat requires an accurate assessment of the worldwide burden of resistance. In an attempt to design anti-TB drugs, the target chosen is a key enzyme of Mtb, O-Succinylbenzoate synthase (OSBS), which is an attractive target for its role in electron transport chain as OSBS is not available in humans. An attempt has been to built the 3-D structure of Mtb-OSBS using online Swiss model server. With sequence alignment and scan motif identification, the importance of evolutionarily significant residues that are of functional importance for ligand binding and that form active sites were well established. Molecular simulation calculations of Mtb-OSBS model indicated evolutionarily conserve residues (Lys110 and Lys212) are the best in molecular interaction with substrate 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC). The in silico mutational analysis of Mtb-OSBS model showed the evolutionarily conserved residues that are essential for catalytic activity. It has been found that active site amino acids of Mtb-OSBS are very important to maintain activity of the enzyme, which provides a novel approach to design new pharmacophore SHCHC substrate analogs against Mtb-OSBS. A series of SHCHC substrate analogs (1–100) compounds have been docked with the amino acid residues at the active site of the Mtb-OSBS enzyme, using AutoDock 4.0, a program employed to perform automated molecular docking. The free energies of binding (∆G) and inhibition constants (Ki) of the docked compounds were calculated by the Lamarckian Genetic Algorithm (LGA). Excellent to good correlations between the calculated and experimental Ki values were reported.

Role of electron transport chain in liver mitochondria of the lamprey Lampetra fluviatilis during a decrease and activation of energy metabolism at the prespawning period

Role of electron transport chain in liver mitochondria of the lamprey Lampetra fluviatilis during a decrease and activation of energy metabolism at the prespawning period

Abstract 995: Blockade Of Electron Transport Preserves The Contents Of Bcl-2 And Cytochrome c In Subsarcolemmal Mitochondria During Ischemia

Cardiac ischemia decreases the rate of oxidative phosphorylation (OXPHOS) and the contents of cardiolipin and cytochrome c (CYTc) in subsarcolemmal mitochondria (SSM) in the isolated rabbit heart. CYTc release first requires damage to the inner mitochondrial membrane to delocalize CYTc to the intermembrane space, followed by breach of the outer membrane. The decrease in cardiolipin content allows CYTc detachment from the inner membrane. It is still unclear how CYTc passes the outer membrane for release into cytosol. We propose that ischemia increases outer-membrane leakage by depletion of bcl-2 content, and that oxidants generated by the electron transport chain (ETC) during ischemia favor bcl-2 depletion. We used blockade of the proximal ETC at complex I during ischemia with amobarbital (AMO) to test the role of ETC during ischemia. Langendorff perfused rabbit hearts were treated with AMO (2.5 mM for 1 min) or vehicle immediately before 30 min global ischemia (37°C). Time controls were perfused for 45 min. SSM were isolated at the end of ischemia. CYTc content (reduced minus oxidized spectra), OXPHOS and bcl-2 (western blotting) were measured. Ischemia decreased OXPHOS with TMPD-ascorbate as substrate (electron donor to complex IV via CYTc) and the contents of CYTc and bcl-2. In contrast, AMO preserves OXPHOS, CYTc and bcl-2. Thus, blockade of electron transport preserves bcl-2 content during ischemia with enhanced CYTc retention by SSM. The ETC contributes to mitochondrial damage during ischemia, depleting cardiolipin in the inner membrane and bcl-2 in the outer membrane favoring the two steps required for release of CYTc from mitochondria during ischemia and reperfusion.