Metabolic changes in Crithidia fasciculata accompanying physiological adaptation to growth in the presence of carbonyl cyanide [formula omitted

Abstract

1. 1. Crithidia fasciculata adapted to growth in the presence of 10 −5 M carbonyl cyanide m- chlorophenylhydrazone (CCCP), an uncoupler of oxidative phosphorylation, maintained adenosine phosphate pools and an adenylate energy charge comparable to those of control cells. 2. 2. CCCP-adapted cells in the presence of the uncoupler respire endogenous substrate at a greater rate than control cells and this effect of CCCP appears readily reversible. 3. 3. CCCP-treated, adapted cells, supporting high endogenous respiration rates, were not responsive to added substrates which significantly stimulated the oxygen utilization of normal C. fasciculata. 4. 4. CCCP-adapted cells, provided with [U- 14C]-labeled proline, utilize this substrate at 67% the rate of control cells, but divide the isotopic label between CO 2 and protein in a ratio identical to that of normal cells. 5. 5. The transport of alamine and proline by adapted C. fasciculata was severely impaired, while the transport of tyrosine and leucine was unaffected.