Siberian Inst. Plant Physiol. Biochem.
The inhibition of adenine nucleotide translocase by carboxyatractyloside (1µM) caused an almost two-fold decrease in the rate of 3H-UTP incorporation into the mitochondrial acid-insoluble fraction (Table 1). The inhibition of the mitochondrial electron transport chain with KCN resulted in more pronounced inhibition of RNA synthesis. The decrease in the rate of RNA synthesis in mitochondria in response to the addition of a classic OP inhibitor, oligomycin, was not so significant, amounting to about 30%. In the presence of OP uncoupler, carbonyl cyanide-m-chlorophenylhydrazone, decrease of the transcription rate was also observed.
The level of DNA-dependent synthesis of DNA did not change, but even increased when ADP was used instead of ATP as a precursor (Table 2). The transcription was strongly inhibited in this case by oligomycin indicating the direct involvement of extramitochondrial ADP after its phosphorylation into the process of RNA biosynthesis. These experimental data also suggest possible functional coupling of OP and RNA synthesis on the basis of additional microcompartments in the inner mitochondrial space.
The effect of membrane active agent, sodium cholate, on mitochondrial transcription depended on the concentrations used: low concentrations of the detergent (100µM) produced significant activation of the RNA synthesis, while higher concentrations (500µM and 1mM) showed strong inhibition effect.
It may be inferred that DNA transcription in maize mitochondria strongly
depends on respiration and oxidative phosphorylation. It is assumed that
the regulation mechanism of mitochondrial genome transcription may involve
conformational changes in DNA-membrane complex during energy transformation
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