Energy transport from mitochondria to nuclei

Abstract

Nuclei isolated from the cells of ungerminated wheat embryos showed an ability to synthesize complex nitrogen compounds when incubated at 30 °C with 0.01 M glutamate, or a complete mixture of amino acids, in the presence of phosphate buffer. The synthesis was greatly increased by addition of 0.01 M ATP and might then be equal to 70% of the original precipitable nitrogen. Reducing the concentration of ATP to 0.001 M virtually abolished its effect, which could be restored by adding a suspension of mitochondria, even when mitochondria and nuclei were separated by a semi-permeable membrane. The nuclear syntheses induced by the presence of 0.001 M ATP + mitochondria were inhibited by DNP and carbon monoxide. It was inferred that the nuclear syntheses were dependent upon energy derived from ATP which was continuously regenerated by the mitochondrial respiration. The implied shuttling of ATP and ADP between nuclei and mitochondria could continue across a membrane. Direct contact of nuclei and mitochondria was not needed. The syntheses of nitrogenous compounds in the nuclei were also inhibited by 0.002 M chloramphenicol. The product was highly resistant to hydrolysis by 0.2 N-NaOH. It was shown to contain considerable amounts of seven different amino acids, in addition to glutamate and other unidentified amino acids in smaller amounts. The bulk of the product was therefore held to be of a protein character.