scholarly journals Regulation of malate oxidation in plant mitochondria. Response to rotenone and exogenous NAD+

1982 ◽  
Vol 208 (3) ◽  
pp. 703-711 ◽  
Author(s):  
J M Palmer ◽  
J P Schwitzguébel ◽  
I M Møller
Keyword(s):  
Nadh Dehydrogenase ◽  
Tricarboxylic Acid Cycle ◽  
Plant Mitochondria ◽  
Jerusalem Artichoke ◽  
Atp Synthesis ◽  
Matrix Space ◽  
Matrix Surface ◽  
The Matrix ◽  
Nadh Dehydrogenases ◽  
Malate Oxidation

Exogenous NAD+ stimulated the rotenone-resistant oxidation of all the NAD+-linked tricarboxylic acid-cycle substrates in mitochondria from Jerusalem artichoke (Helianthus tuberosus L.) tubers. The stimulation was not removed by the addition of EGTA, which is known to inhibit the oxidation of exogenous NADH. It is therefore concluded that added NAD+ gains access to the matrix space and stimulates oxidation by the rotenone-resistant NADH dehydrogenase located on the matrix surface of the inner membrane. Added NAD+ stimulated the activity of malic enzyme and displaced the equilibrium of malate dehydrogenase; both observations are consistent with entry of NAD+ into the matrix space. Analysis of products of malate oxidation showed that rotenone-resistant oxygen uptake only occurred when the concentration of oxaloacetate was low and that of NADH was high. Thus it is proposed that the concentration of NADH regulates the activity of the two internal NADH dehydrogenases. Evidence is presented to suggest that the rotenone-resistant NADH dehydrogenase is engaged under conditions of high phosphorylation potential, which restricts electron flux through the rotenone-sensitive dehydrogenase (coupled to ATP synthesis).

scholarly journals Slow passive diffusion of NAD+ between intact isolated plant mitochondria and suspending medium

1983 ◽  
Vol 216 (2) ◽  
pp. 443-450 ◽  
Author(s):  
M Neuburger ◽  
R Douce
Keyword(s):  
Solanum Tuberosum ◽  
Plant Mitochondria ◽  
Passive Diffusion ◽  
High Rate ◽  
O2 Consumption ◽  
Initial State ◽  
Matrix Space ◽  
Isolated Mitochondria ◽  
The Matrix ◽  
Isopycnic Centrifugation

Isolated potato (Solanum tuberosum) tuber mitochondria purified by isopycnic centrifugation in density gradients of Percoll were found to be highly intact, to be devoid of extramitochondrial contaminations and to retain a high rate of O2 consumption. When suspended in a medium that avoided rupture of the outer membrane, intact purified mitochondria progressively lost their NAD+ content by passive diffusion. This led to a slow decrease of oxoglutarate-dependent O2 consumption by isolated mitochondria. Addition of NAD+ to the medium restored the initial State-3 rate of oxoglutarate oxidation. The rate of NAD+ accumulation in the matrix space was concentration-dependent, exhibited Michaelis-Menten kinetics and was strongly inhibited by the analogue N-4-azido-2-nitrophenyl-4-aminobutyryl-NAD+.

scholarly journals Immunological analysis of plant mitochondrial NADH dehydrogenases

1986 ◽  
Vol 236 (1) ◽  
pp. 201-207 ◽  
Author(s):  
I R Cottingham ◽  
M W J Cleeter ◽  
C I Ragan ◽  
A L Moore
Keyword(s):  
Nadh Dehydrogenase ◽  
Plant Mitochondria ◽  
The Other ◽  
Mitochondrial Inner Membrane ◽  
Crossed Immunoelectrophoresis ◽  
Specific Antisera ◽  
Molecular Masses ◽  
Nadh Dehydrogenases ◽  
Single Polypeptide ◽  
Triton X

Plant mitochondrial NADH dehydrogenases were analysed by two immunological strategies. The first exploited an antiserum raised to a preparation of SDS-solubilized mitochondrial-inner-membrane particles. By using a combination of activity-immunoprecipitation and crossed immunoelectrophoresis, it was shown that Triton X-100-solubilized membranes contain at least three immunologically distinct NADH dehydrogenases. Two of these were subsequently isolated by line immunoelectrophoresis and analysed for polypeptide composition: one contained three polypeptides with molecular masses of 75, 62 and 41 kDa; the other was a single polypeptide with a molecular mass of 53 kDa. The other approach was to probe plant mitochondrial membranes with antibodies raised to a purified preparation of ox heart rotenone-sensitive NADH dehydrogenase and subunits thereof. Cross-reactions were observed with the subunit-specific antisera against the 30 and 49 kDa ox heart proteins. However, the molecular masses of the equivalent polypeptides in plant mitochondria are slightly lower, at 27 and 46 kDa respectively.

scholarly journals The activation of non-phosphorylating electron transport by adenine nucleotides in Jerusalem-artichoke (Helianthus tuberosus) mitochondria

1975 ◽  
Vol 152 (3) ◽  
pp. 637-645 ◽  
Author(s):  
R Sotthibandhu ◽  
J M Palmer
Keyword(s):  
Cytochrome B ◽  
Redox State ◽  
Nadh Dehydrogenase ◽  
Adenine Nucleotides ◽  
Plant Mitochondria ◽  
Jerusalem Artichoke ◽  
Simultaneous Oxidation ◽  
Carbonyl Cyanide ◽  
Bongkrekic Acid ◽  
Complex Manner

In isolated plant mitochondria the oxidation of both succinate and exogenous NADH responded in the expected manner to the addition of ADP or uncoupling agents, and the uncoupled rate of respiration was often in excess of the rate obtained in the presence of ADP. However, the oxidation of NAD+-linked substrates responded in a much more complex manner to the addition of ADP or uncoupling agents such as carbonyl cyanide p-trifluoromethoxyphenylhydrazone to mitochondria oxidizing pyruvate plus malate failed to result in a reliable stimulation; this uncoupled rate could be stimulated by adding AMP or ADP in the presence of oligomycin or bongkrekic acid. Spectrophometric measurements showed that the addition of AMP or ADP resulted in the simultaneous oxidation of endogenous nicotinamide nucleotide and the reduction of cytochrome b. ADP was only effective in bringing about these changes in redox state in the presence of Mg2+ whereas AMP did not require Mg2+. It was concluded that AMP activated the flow of electrons from endogenous nicotinamide nucleotide to cytochrome b, possible at the level of the internal NADH dehydrogenase.

scholarly journals The mitochondrial pyruvate carrier (MPC) complex is one of three pyruvate-supplying pathways that sustain Arabidopsis respiratory metabolism

2021 ◽  
Author(s):  
Xuyen H. Le ◽  
Chun-Pong Lee ◽  
A. Harvey Millar
Keyword(s):  
Plant Growth ◽  
Plant Mitochondria ◽  
Complex Function ◽  
Tca Cycle ◽  
Respiratory Metabolism ◽  
The Tca Cycle ◽  
Mitochondrial Pyruvate Carrier ◽  
The Matrix ◽  
Branched Chain ◽  
Malate Oxidation

AbstractMalate oxidation by plant mitochondria enables the generation of both oxaloacetate (OAA) and pyruvate for tricarboxylic acid (TCA) cycle function, potentially eliminating the need for pyruvate transport into mitochondria in plants. Here we show that the absence of the mitochondrial pyruvate carrier 1 (MPC1) causes the co-commitment loss of its orthologs, MPC3/MPC4, and eliminates pyruvate transport into Arabidopsis mitochondria, proving it is essential for MPC complex function. While the loss of either MPC or mitochondrial pyruvate-generating NAD-malic enzyme (NAD-ME) did not cause vegetative phenotypes, the lack of both reduced plant growth and caused an increase in cellular pyruvate levels, indicating a block in respiratory metabolism, and elevated the levels of branched-chain amino acids at night, a sign of alterative substrate provision for respiration. 13C-pyruvate feeding of leaves lacking MPC showed metabolic homeostasis were largely maintained except for alanine and glutamate, indicating that transamination contributes to restoration of the metabolic network to an operating equilibrium by delivering pyruvate independently of MPC into the matrix. Inhibition of alanine aminotransferases (AlaAT) when MPC1 is absent resulted in extremely retarded phenotypes in Arabidopsis, suggesting all pyruvate-supplying enzymes work synergistically to support the TCA cycle for sustained plant growth.

scholarly journals Carbon and Nitrogen Sources Have No Impact on the Organization and Composition of Ustilago maydis Respiratory Supercomplexes

2021 ◽  
Vol 7 (1) ◽  
pp. 42
Author(s):  
Deyamira Matuz-Mares ◽  
Oscar Flores-Herrera ◽  
Guadalupe Guerra-Sánchez ◽  
Lucero Romero-Aguilar ◽  
Héctor Vázquez-Meza ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Polyacrylamide Gel Electrophoresis ◽  
Atp Synthesis ◽  
Nitrogen Sources ◽  
Growth Conditions ◽  
Energy Conditions ◽  
Respiratory Complexes ◽  
Respiratory Supercomplexes ◽  
Nadh Dehydrogenases ◽  
Reduced Nicotinamide Adenine Dinucleotide

Respiratory supercomplexes are found in mitochondria of eukaryotic cells and some bacteria. A hypothetical role of these supercomplexes is electron channeling, which in principle should increase the respiratory chain efficiency and ATP synthesis. In addition to the four classic respiratory complexes and the ATP synthase, U. maydis mitochondria contain three type II NADH dehydrogenases (NADH for reduced nicotinamide adenine dinucleotide) and the alternative oxidase. Changes in the composition of the respiratory supercomplexes due to energy requirements have been reported in certain organisms. In this study, we addressed the organization of the mitochondrial respiratory complexes in U. maydis under diverse energy conditions. Supercomplexes were obtained by solubilization of U. maydis mitochondria with digitonin and separated by blue native polyacrylamide gel electrophoresis (BN-PAGE). The molecular mass of supercomplexes and their probable stoichiometries were 1200 kDa (I1:IV1), 1400 kDa (I1:III2), 1600 kDa (I1:III2:IV1), and 1800 kDa (I1:III2:IV2). Concerning the ATP synthase, approximately half of the protein is present as a dimer and half as a monomer. The distribution of respiratory supercomplexes was the same in all growth conditions. We did not find evidence for the association of complex II and the alternative NADH dehydrogenases with other respiratory complexes.

Alternaria toxins and their effects on host plants

1995 ◽  
Vol 73 (S1) ◽  
pp. 453-458 ◽  
Author(s):  
Hiroshi Otani ◽  
Keisuke Kohmoto ◽  
Motoichiro Kodama
Keyword(s):  
Plasma Membrane ◽  
Host Plants ◽  
Plasma Membranes ◽  
Early Effect ◽  
The Third ◽  
The Matrix ◽  
Electrolyte Loss ◽  
Host Specific Toxins ◽  
Acid Structure ◽  
Malate Oxidation

There are now nine or more Alternaria pathogens that produce host-specific toxins, and the structures of most of the toxins have been elucidated. Alternaria host-specific toxins are classified in three groups in terms of the primary site action. ACT-, AF-, and AK-toxins have in common an epoxy-decatrienoic acid structure and exert their primary effect on the plasma membrane of susceptible cells. A rapid increase in electrolyte loss from tissues and invaginations in the plasma membranes are common effects of these toxins. The second group is represented by ACR(L)-toxin, which induces changes in mitochondria, including swelling, vesiculation of cristae, decrease in the electron density of the matrix, increase in the rate of NADH oxidation, and inhibition of malate oxidation. The third group consists of AM-toxin, which appears to exert an early effect on both chloroplasts and plasma membranes. AM-toxin induces vesiculation of grana lamellae, inhibition of CO2 fixation, invagination of plasma membranes, and electrolyte loss. The roles of host-specific toxins in pathogenesis are discussed. Key words: Alternaria, host-specific toxin, plasma membrane, mitochondrion, chloroplast.

Recent Advances in Biohybrid Materials for Tissue Engineering and Regenerative Medicine

2016 ◽  
Vol 04 (01) ◽  
pp. 1640001 ◽  
Author(s):  
Ying Wan ◽  
Xing Li ◽  
Shenqi Wang
Keyword(s):  
Tissue Engineering ◽  
Regenerative Medicine ◽  
Cell Function ◽  
Rapid Prototype ◽  
Artificial Organs ◽  
Specific Cell ◽  
Cell Matrix ◽  
Matrix Surface ◽  
The Matrix ◽  
Cell Matrix Interactions

Biohybrid materials play an important role in tissue engineering, artificial organs and regenerative medicine due to their regulation of cell function through specific cell–matrix interactions involving integrins, mostly those of fibroblasts and myofibroblasts, and ligands on the matrix surface, which have become current research focus. In this paper, recent progress of biohybrid materials, mainly including main types of biohybrid materials, rapid prototype (RP) technique for construction of 3D biohybrid materials, was reviewed in detail; moreover, their applications in tissue engineering, artificial organs and regenerative medicine were also reviewed in detail. At last, we address the challenges biohybrid materials may face.

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