Reversal of succinate-mediated catabolite repression of alkylsulfatase in Pseudomonas aeruginosa by 2,4-dinitrophenol and by sodium malonate

Abstract

The Kreb's cycle intermediates and related metabolites (e.g., acetate) repressed the induced synthesis of alkylsulfatase in resting cell suspensions of Pseudomonas aeruginosa. At concentrations which caused substantial repression, sodium succinate as well as sodium malate, fumarate, and α-ketoglutarate were oxidized to yield consistently high levels of ATP throughout the induction period. Sodium oxalacetate which was markedly less effective as a metabolite repressor generated high ATP levels only during the first 2 h of the induction period. The addition of 2,4-dinitrophenol or sodium malonate to cell suspensions containing the inducer (sodium hexan-1-yl sulfate) and succinate overcame repression of alkylsulfatase formation and resulted in a reduction in the ATP content to levels found in cells exposed only to inducer. An apparent stimulation of alkylsulfatase induction occurred in the absence of succinate when cells were incubated with 2,4-dinitrophenol and inducer. In this case, the ATP content of the cell suspension fell to levels substantially below those occurring as a result of inducer catabolism. Collectively, these data suggest that the effectiveness of succinate as a metabolite repressor is related to the ATP levels generated as a consequence of succinate oxidation.