Key points are not available for this paper at this time.
Cells of Escherichia coli which enter a phase of starvation for Pi induce the synthesis of the nucleotide guanosine 3',5'-bispyrophosphate (ppGpp). This induction is relA independent but depends on the spoT gene product. A mutant unable to produce ppGpp is impaired in the expression of two genes which belong to the pho regulon, a defect which is dependent on the product of spoT. We suggest that ppGpp is essential for the proper induction of the genes which belong to the pho regulon.
Spira et al. (Sat,) studied this question.