Enzyme induction in Streptomyces hydrogenas, VII. Short-term accumulation of guanosine polyphosphates

Cells of Streptomyces hydrogenans (ATCC 19631) synthesize guanosine 3'(2')-diphosphate 5'-triphosphate (pppGpp) and guanosine 3'(2')-diphosphate 5'-diphosphate (ppGpp). 10 to 20 min after addition of steroids to the culture medium, the amount of pppGpp and ppGpp increases 2- to 3-fold. At the same time, the cellular amount of both ATP and GTP has been found to increase. While "shift down" experiments arrest growth of the cells temporarily, steroids do not impair cell division of Streptomyces hydrogenans. It is suggested that ppGpp and pppGpp mediate the regulatory shut off of nucleic acid synthesis or control their increased turnover triggered by the steroids.