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#Unit 3. Fundamental Processes
The E. coli rrn promoters are also regulated by a pair of small molecules: the initiating NTP (the iNTP) and an alarmone, guanosine 5 -diphosphate 3-diphosphate (ppGpp).
1. An abundance of iNTP indicates that the concentration of nucleotides is high, and therefore it is appropriate to synthesize plenty of rRNA.
2. Accordingly, iNTP stabilizes the open promoter complex, stimulating transcription.
3. On the other hand, when cells are starved for amino acids, protein synthesis cannot occur readily and the need for ribosomes (and rRNA) decreases.
