The feedback response of Escherichia coli rRNA synthesis is not identical to the mechanism of growth rate-dependent control.

Growth rate-independent rrn P1 promoter mutants were tested for their ability to respond to changes in rrn gene dosage. Most were found to be normal for the feedback response. In addition, cellular Levels of the initiating nucleoside triphosphates remained unchanged when the rrn gene dosage was altered. These results suggest that the feedback response cannot be the mechanism for growth rate-dependent control of rRNA synthesis and that the relationship between these two processes mag be more complicated than is currently understood.