DksA and ppGpp regulate transcription of both rRNA and r-proteins

During the stringent response ppGpp together with a small protein DksA bind to the RNA polymerase and down-regulate transcription of the rRNA genes. It makes sense - there is no need for more ribosomes if there are not enough amino acids. However, ribosomes consist not only of rRNA but also of ribosomal proteins, and if the cell stops making rRNA it would make sense to stop making the ribosomal proteins as well.

And it turnes out that ppGpp and DksA do that too. Makes total sense, again. It is quite rare that something about the stringent response makes total sense, but there you are.

References:

Lemke, J. J., Sanchez-Vazquez, P., Burgos, H. L., Hedberg, G., Ross, W., & Gourse, R. L. (2011). Direct regulation of Escherichia coli ribosomal protein promoters by the transcription factors ppGpp and DksA. Proceedings of the National Academy of Sciences of the United States of America, 108(14), 5712–5717.