Likewise, a reduction in the GTP pool (from 3.2 to 0.8 μmol/g dry weight) resulted in 25%–30% escape of attenuation. However, when the UTP pool was reduced (from 1.3 to 0.2 μmol/g dry weight) nearly 100% of transcription passed the attenuator. When pools of both UTP and GTP were high only 5%–6% of the mRNA chains were continued into the pyrE gene. It was found that the greater part of pyrE gene regulation by the nucleotides takes place at the intercistronic attenuator and that promoter control contributes only little, ca. Expression of the hybrid genes was studied in a bacterium with mutations that permit changes in the UTP and GTP pools during exponential growth. We have used the galK gene, minus its promoter, to quantitate transcription of the orfE-pyrE operon of Escherichia coli in front of and after the intercistronic attenuator.
0 kommentar(er)
