Alteration of stringent response of the Escherichia coli rnpB promoter by mutations in the -35 region.

ABSTRACT

It is well known that the GC-rich discriminator region between the -10 region and the transcription start site is important for the stringent control of the transcription. However, the discriminator activity is influenced by flanking regions, in particular in conjunction with the promoter -35 and -10 sequences. In this study, we changed the sequence in the -35 region of the rnpB P-1 promoter to see how such changes affect the stringent control. The sequence variation in the -35 region changed the stringent signal. The change to the consensus TTGACA sequence caused the most prominent relieving effect on stringent repression of the rnpB transcription. The spacing between the -35 and -10 regions is also significant because the relieving effect of the TTGACA was offset by the change of the spacing from 17 to 16 bp. The nucleotide just upstream of the -35 region contributes toward generating stringent signals as well.