Journal Article

ATP Synthesis Driven by α-Keto Acid-stimulated Alternative Oxidase in Pea Leaf Mitochondria

Angelo Vianello, Enrico Braidot, Elisa Petrussa and Francesco Macri

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 38, issue 12, pages 1368-1374
Published in print January 1997 | ISSN: 0032-0781
Published online January 1997 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029131
ATP Synthesis Driven by α-Keto Acid-stimulated Alternative Oxidase in Pea Leaf Mitochondria

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The electrical potential difference (δΨ) generation and ATP synthesis due to α-keto acid-stimulated alternative oxidase activity in pea leaf mitochondria, energized by malate plus glutamate, was studied. In the absence of α-keto acids, δΨwas ca. 60% collapsed by KCN or antimycin A (AA), while the remaining part (ca. 30%) was dissipated by salicyl-hydroxamic acid (SHAM). The presence of α-keto acids (pyruvate or iodoacetate), known to stimulate the alternative oxidase, caused a decrease in the KCN- or AA-sensitive component of δΨ(ca. 30%), which was accompanied by an increase in the SHAM-sensitive one. When mitochondria were energized by exogenous NADH, succinate or duroquinol, δΨ was completely collapsed by KCN or AA, either in the presence or absence of α-keto acids. ADP partially collapsed the SHAM-sensitive component of δΨ, and oligomycin restored this dissipation. In the presence of pyruvate or iodoacetate, ATP content in KCN-treated mitochondria was ca. 40% of control, while that in SHAM plus KCN-inhibited mitochondria was negligible. ADP stimulated oxygen uptake only in the presence of KCN (respiratory control ratio = 1.7), but not in the presence of KCN plus SHAM. It is concluded that α-keto acids, stimulating the oxidation of NAD-linked substrates through the alternative oxidase, lead to an increase in the SHAM-sensitive component of δΨvia complex I, thus increasing the contribution of this pathway to ATP synthesis when the cyto-chrome oxidase is restricted.

Keywords: Alternative oxidase; ATP synthesis; Electrical potential; Mitochondria; Pisum sativum

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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