Alterations in the beta Flap and beta ' Dock Domains of the RNA Polymerase Abolish NusA-Mediated Feedback Regulation of the metY-nusA-infB Operon

作者：Bylund Goran O; Nord Stefan; Lovgren J Mattias; Wikstrom P Mikael^*

来源：Journal of Bacteriology, 2011, 193(16): 4113-4122.

DOI：10.1128/JB.00196-11

The RimM protein in Escherichia coli is important for the in vivo maturation of 30S ribosomal subunits and a Delta rimM mutant grows poorly due to assembly and translational defects. These deficiencies are suppressed partially by mutations that increase the synthesis of another assembly protein, RbfA, encoded by the metY-nusA-infB operon. Among these suppressors are mutations in nusA that impair the NusA-mediated negative-feedback regulation at internal intrinsic transcriptional terminators of the metY-nusA-infB operon. We describe here the isolation of two new mutations, one in rpoB and one in rpoC (encoding the beta and beta ' subunits of the RNA polymerase, respectively), that increase the synthesis of RbfA by preventing NusA from stimulating termination at the internal intrinsic transcriptional terminators of the metY-nusA-infB operon. The rpoB2063 mutation changed the isoleucine in position 905 of the beta flap-tip helix to a serine, while the rpoC2064 mutation duplicated positions 415 to 416 (valine-isoleucine) at the base of the beta ' dock domain. These findings support previously published in vitro results, which have suggested that the beta flap-tip helix and beta ' dock domain at either side of the RNA exit tunnel mediate the binding to NusA during transcriptional pausing and termination.

• 出版日期2011-8