The energy-dependent degradation of guanosine 5'-diphosphate 3'-diphosphate in Escherichia coli. Lack of correlation with ATP levels in vivo and role of the transmembrane proton gradient.

摘要: Different inhibitors of the energy metabolism have been assayed in Escherichia coli K12 for their ability to increase level guanosine 5′-diphosphate 3′-diphosphate (ppGpp) as a consequence restriction its degradation. Inhibitors respiration and uncouplers oxidative phosphorylations had effects similar carbon-source-induced downshifts while ATPase inhibitor dicyclohexylcarbodiimide was less efficient. The uncoupler carbonylcyanide p-fluoro methoxyphenylhydrazone (FCCP) on ppGpp degradation were compared drug-permeable envelope mutant. At concentrations sufficient deplete pool ATP by 50%, only FCCP able block Moreover, also inhibited ATPase-deficient strain growing glucose carbon source while, expected, it did not change ATP. It is concluded, according Mitchell's chemiosmotic hypothesis, that, vivo, integrity transmembrane proton gradient rather than size prerequisite normal processing energy-dependent ppGpp.