Mechanisms of 5'-Inosinic Acid Accumulation by Permeability Mutants of Brevibacterium ammoniagenes. IV. Excretion Mechanisms of 5'-IMP

抄録

Excretion of intracellular 5'-inosinic acid (5'-IMP) of a series of mutants of Brevibacterium ammoniagenes selected for high 5'-IMP productivity was measured by incubating the washed cells in a phosphate buffer at 30°C. In the highest producer, KY13369, intracellular 5'-IMP was excreted partly as 5'-IMP and partly as hypoxanthine (Hx), after degradation, to the outside, which indicates the existence of two excretion systems of intracellular 5'-IMP. One is a direct excretion system of 5'-IMP and the other is an indirect excretion system coupled with degradation. 5'-IMP accumulation via the direct excretion system by the washed cells was stimulated by various energy sources and was completely inhibited by KCN, NaN₃, DNPand CCCP, providing the evidence that excretion of intracellular 5'-IMP is dependent on energy-yielding reactions. The increased 5'-IMP productivity of KY13369 can be ascribed to the increased direct excretion system and to the changes of the indirect excretion system, which was more susceptible to glucose inhibition.