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Antimycin A treatment decreases respiratory internal rotenone-insensitive NADH oxidation capacity in potato leaves.

Geisler DA, Johansson FI, Svensson AS, Rasmusson AG - BMC Plant Biol. (2004)

Bottom Line: The internal rotenone-insensitive NADH oxidation decreases after antimycin A treatment of potato leaves.However, the decrease is not due to changes in expression of known nda genes.One consequence of the lower NADH dehydrogenase capacity may be a stabilisation of the respiratory chain reduction level, should the overall capacity of the cytochrome and the alternative pathway be restricted.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden. daniela.geisler@cob.lu.se

ABSTRACT

Background: The plant respiratory chain contains several energy-dissipating enzymes, these being type II NAD(P)H dehydrogenases and the alternative oxidase, not present in mammals. The physiological functions of type II NAD(P)H dehydrogenases are largely unclear and little is known about their responses to stress. In this investigation, potato plants (Solanum tuberosum L., cv. Desiree) were sprayed with antimycin A, an inhibitor of the cytochrome pathway. Enzyme capacities of NAD(P)H dehydrogenases (EC 1.6.5.3) and the alternative oxidase were then analysed in isolated leaf mitochondria.

Results: We report a specific decrease in internal rotenone-insensitive NADH dehydrogenase capacity in mitochondria from antimycin A-treated leaves. External NADPH dehydrogenase and alternative oxidase capacities remained unaffected by the treatment. Western blotting revealed no change in protein abundance for two characterised NAD(P)H dehydrogenase homologues, NDA1 and NDB1, nor for two subunits of complex I. The alternative oxidase was at most only slightly increased. Transcript levels of nda1, as well as an expressed sequence tag derived from a previously uninvestigated closely related potato homologue, remained unchanged by the treatment. As compared to the daily rhythm-regulated nda1, the novel homologue displayed steady transcript levels over the time investigated.

Conclusions: The internal rotenone-insensitive NADH oxidation decreases after antimycin A treatment of potato leaves. However, the decrease is not due to changes in expression of known nda genes. One consequence of the lower NADH dehydrogenase capacity may be a stabilisation of the respiratory chain reduction level, should the overall capacity of the cytochrome and the alternative pathway be restricted.

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External NADPH oxidation with DcQ as electron acceptor. NADPH dehydrogenase activities in the presence of Ca2+ and antimycin A are presented as percentage of control in each experiment. No activity was seen without Ca2+ added to the reaction. Error bars indicate standard deviation (n = 2). Control activities were 315 and 479 nmol NADPH min-1 mg-1 in the two experiments. Samples are denoted as for Fig. 1.
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Figure 2: External NADPH oxidation with DcQ as electron acceptor. NADPH dehydrogenase activities in the presence of Ca2+ and antimycin A are presented as percentage of control in each experiment. No activity was seen without Ca2+ added to the reaction. Error bars indicate standard deviation (n = 2). Control activities were 315 and 479 nmol NADPH min-1 mg-1 in the two experiments. Samples are denoted as for Fig. 1.

Mentions: Since all other enzymes potentially capable of catalysing NAD(P)H oxidation to short chained quinone analogues, (e.g. complex I and dihydrolipoamide dehydrogenase), are located inside the inner membrane permeability barrier, external NADPH dehydrogenase can be measured directly using decyl-ubiquinone (DcQ) as acceptor. This activity is also independent of the capacity of enzymes further downstream in the electron transport chain. Fig. 2 shows that NADPH oxidation to DcQ in isolated mitochondria was mainly unaffected by leaf treatment with antimycin A. Activities varied somewhat between experiments but the normalised averages allow the conclusion that no decrease in external NADPH dehydrogenase capacity occurred as a result of antimycin A leaf treatment. The activity of cytochrome c oxidase, located downstream of the bc1 complex, was similar in mitochondria from control and antimycin A-treated leaves (data not shown).


Antimycin A treatment decreases respiratory internal rotenone-insensitive NADH oxidation capacity in potato leaves.

Geisler DA, Johansson FI, Svensson AS, Rasmusson AG - BMC Plant Biol. (2004)

External NADPH oxidation with DcQ as electron acceptor. NADPH dehydrogenase activities in the presence of Ca2+ and antimycin A are presented as percentage of control in each experiment. No activity was seen without Ca2+ added to the reaction. Error bars indicate standard deviation (n = 2). Control activities were 315 and 479 nmol NADPH min-1 mg-1 in the two experiments. Samples are denoted as for Fig. 1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC424582&req=5

Figure 2: External NADPH oxidation with DcQ as electron acceptor. NADPH dehydrogenase activities in the presence of Ca2+ and antimycin A are presented as percentage of control in each experiment. No activity was seen without Ca2+ added to the reaction. Error bars indicate standard deviation (n = 2). Control activities were 315 and 479 nmol NADPH min-1 mg-1 in the two experiments. Samples are denoted as for Fig. 1.
Mentions: Since all other enzymes potentially capable of catalysing NAD(P)H oxidation to short chained quinone analogues, (e.g. complex I and dihydrolipoamide dehydrogenase), are located inside the inner membrane permeability barrier, external NADPH dehydrogenase can be measured directly using decyl-ubiquinone (DcQ) as acceptor. This activity is also independent of the capacity of enzymes further downstream in the electron transport chain. Fig. 2 shows that NADPH oxidation to DcQ in isolated mitochondria was mainly unaffected by leaf treatment with antimycin A. Activities varied somewhat between experiments but the normalised averages allow the conclusion that no decrease in external NADPH dehydrogenase capacity occurred as a result of antimycin A leaf treatment. The activity of cytochrome c oxidase, located downstream of the bc1 complex, was similar in mitochondria from control and antimycin A-treated leaves (data not shown).

Bottom Line: The internal rotenone-insensitive NADH oxidation decreases after antimycin A treatment of potato leaves.However, the decrease is not due to changes in expression of known nda genes.One consequence of the lower NADH dehydrogenase capacity may be a stabilisation of the respiratory chain reduction level, should the overall capacity of the cytochrome and the alternative pathway be restricted.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept of Cell and Organism Biology, Lund University, Sölvegatan 35B, Lund, (SE-223 62), Sweden. daniela.geisler@cob.lu.se

ABSTRACT

Background: The plant respiratory chain contains several energy-dissipating enzymes, these being type II NAD(P)H dehydrogenases and the alternative oxidase, not present in mammals. The physiological functions of type II NAD(P)H dehydrogenases are largely unclear and little is known about their responses to stress. In this investigation, potato plants (Solanum tuberosum L., cv. Desiree) were sprayed with antimycin A, an inhibitor of the cytochrome pathway. Enzyme capacities of NAD(P)H dehydrogenases (EC 1.6.5.3) and the alternative oxidase were then analysed in isolated leaf mitochondria.

Results: We report a specific decrease in internal rotenone-insensitive NADH dehydrogenase capacity in mitochondria from antimycin A-treated leaves. External NADPH dehydrogenase and alternative oxidase capacities remained unaffected by the treatment. Western blotting revealed no change in protein abundance for two characterised NAD(P)H dehydrogenase homologues, NDA1 and NDB1, nor for two subunits of complex I. The alternative oxidase was at most only slightly increased. Transcript levels of nda1, as well as an expressed sequence tag derived from a previously uninvestigated closely related potato homologue, remained unchanged by the treatment. As compared to the daily rhythm-regulated nda1, the novel homologue displayed steady transcript levels over the time investigated.

Conclusions: The internal rotenone-insensitive NADH oxidation decreases after antimycin A treatment of potato leaves. However, the decrease is not due to changes in expression of known nda genes. One consequence of the lower NADH dehydrogenase capacity may be a stabilisation of the respiratory chain reduction level, should the overall capacity of the cytochrome and the alternative pathway be restricted.

Show MeSH