Dataset Information

Succinate-driven reverse electron transport in the respiratory chain of plant mitochondria. The effects of rotenone and adenylates in relation to malate and oxaloacetate metabolism.

ABSTRACT: The effects of rotenone on the succinate-driven reduction of matrix nicotinamide nucleotides were investigated in Percoll-purified mitochondria from potato (Solanum tuberosum) tubers. Depending on the presence of ADP or ATP, rotenone caused an increase or a decrease in the level of reduction of the matrix nicotinamide nucleotides. The increase in the reduction induced by rotenone in the presence of ADP was linked to the oxidation of the malate resulting from the oxidation of succinate. Depending on the experimental conditions, malic enzyme (at pH 6.6 or in the presence of added CoA) or malate dehydrogenase (at pH 7.9) were involved in this oxidation. At pH 7.9, the oxaloacetate produced progressively inhibited the succinate dehydrogenase. In the presence of ATP the production of oxaloacetate was stopped, and succinate dehydrogenase was protected from inhibition by oxaloacetate. However, previously accumulated oxaloacetate transitorily decreased the level of the reduction of the NAD+ driven by succinate, by causing the reversal of the malate dehydrogenase reaction. Under these conditions (i.e. presence of ATP), rotenone strongly inhibited the reduction of NAD+ by succinate-driven reverse electron flow. No evidence for an active reverse electron transport through a rotenone-insensitive path could be obtained. The inhibitory effect of rotenone was masked if malate had previously accumulated, owing to the malate-oxidizing enzymes which reduced part or all of the matrix NAD+.

SUBMITTER: Rustin P

PROVIDER: S-EPMC1149945 | biostudies-other | 1991 Feb

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Three succinate coenzyme A (succinate-CoA) ligases (SucCD) from Escherichia coli, Advenella mimigardefordensis DPN7(T), and Alcanivorax borkumensis SK2 were characterized regarding their substrate specificity concerning succinate analogues. Previous studies had suggested that SucCD enzymes might be promiscuous toward succinate analogues, such as itaconate and 3-sulfinopropionate (3SP). The latter is an intermediate of the degradation pathway of 3,3'-dithiodipropionate (DTDP), a precursor for the biotechnical production of polythioesters (PTEs) in bacteria. The sucCD genes were expressed in E. coli BL21(DE3)/pLysS. The SucCD enzymes of E. coli and A. mimigardefordensis DPN7(T) were purified in the native state using stepwise purification protocols, while SucCD from A. borkumensis SK2 was equipped with a C-terminal hexahistidine tag at the SucD subunit. Besides the preference for the physiological substrates succinate, itaconate, ATP, and CoA, high enzyme activity was additionally determined for both enantiomeric forms of malate, amounting to 10 to 21% of the activity with succinate. Km values ranged from 2.5 to 3.6 mM for l-malate and from 3.6 to 4.2 mM for d-malate for the SucCD enzymes investigated in this study. As l-malate-CoA ligase is present in the serine cycle for assimilation of C1 compounds in methylotrophs, structural comparison of these two enzymes as members of the same subsubclass suggested a strong resemblance of SucCD to l-malate-CoA ligase and gave rise to the speculation that malate-CoA ligases and succinate-CoA ligases have the same evolutionary origin. Although enzyme activities were very low for the additional substrates investigated, liquid chromatography/electrospray ionization-mass spectrometry analyses proved the ability of SucCD enzymes to form CoA-thioesters of adipate, glutarate, and fumarate. Since all SucCD enzymes were able to activate 3SP to 3SP-CoA, we consequently demonstrated that the activation of 3SP is not a unique characteristic of the SucCD from A. mimigardefordensis DPN7(T). The essential role of sucCD in the activation of 3SP in vivo was proved by genetic complementation.

Dataset Information

Succinate-driven reverse electron transport in the respiratory chain of plant mitochondria. The effects of rotenone and adenylates in relation to malate and oxaloacetate metabolism.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets