Effect of prostaglandin E1-induced elevation of cyclic AMP on glucose repression in the lactic streptococci.

Cyclic adenosine 3', 5' -monophosphate (cAMP) activity was observed in Streptococcus lactis C2, Streptococcus cremoris C10, Streptococcus diacetlactis 18-16, and Streptococcus thermophilus C3. In vitro assays of cell-free extracts obtaianed from S. lactis C2 showed that the cAMP-associated enzymes adenyl cyclase and phosphodiesterase were also present. In vitro experiments showed that prostaglandin E1 (PGE) stimulation of adenyl cyclase increased cAMP concentrations approximately fivefold, and in vivo studies showed that PGE treatment of S. lactis C2 increased intracellular cAMP concentrations twofold. Futhermore, PGE-induced elevation of intracellular cAMP levels was shown to prevent the repression of ss-D-phosphogalactoside galactohydrolase synthesis by glucose.