Ribosome Biogenesis - in Prokaryotes

In Prokaryotes

There are 52 genes that encode the ribosomal proteins and they can be found in 20 operons within prokaryotic DNA. Regulation of ribosome synthesis hinges on the regulation of the rRNA itself.

First, a reduction in aminoacyl-tRNA will cause the prokaryotic cell to respond by lowering transcription and translation. This occurs through a series of steps, beginning with stringent factor binding to ribosomes and catalyzing the reaction:
GTP + ATP --> pppGpp + AMP
The γ-phosphate is then removed and ppGpp will bind to and inhibit RNA polymerase. This binding causes a reduction in rRNA transcription. A reduced amount of rRNA means that ribosomal proteins (r-proteins) will be translated but will not have an rRNA to bind to. Instead, they will negatively feedback and bind to their own mRNA, repressing r-protein synthesis. Note that r-proteins preferentially bind to its complementary rRNA if it is present, rather than mRNA.

The ribosome operons also include the genes for RNA polymerase and elongation factors (used in RNA translation). Regulation of all of these genes at once illustrate the coupling between transcription and translation in prokaryotes.