Modular organization of the NusA- and NusG-stimulated RNA polymerase pause signal that participates in the Bacillus subtilis trp operon attenuation mechanism

Smarajit Mondal, Alexander V. Yakhnin, Paul Babitzke

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

The Bacillus subtilis trpEDCFBA operon is regulated by a transcription attenuation mechanism in which tryptophan-activated TRAP binds to the nascent transcript and blocks the formation of an antiterminator structure such that the formation of an overlapping intrinsic terminator causes termination in the 5' untranslated region (5' UTR). In the absence of bound TRAP, the antiterminator forms and transcription continues into the trp genes. RNA polymerase pauses at positions U107 and U144 in the 5' UTR. The general transcription elongation factors NusA and NusG stimulate pausing at both positions. NusG-stimulated pausing at U144 requires sequence-specific contacts with a T tract in the nontemplate DNA (ntDNA) strand within the paused transcription bubble. Pausing at U144 participates in a trpE translation repression mechanism. Since U107 just precedes the critical overlap between the antiterminator and terminator structures, pausing at this position is thought to participate in attenuation. Here we carried out in vitro pausing and termination experiments to identify components of the U107 pause signal and to determine whether pausing affects the termination efficiency in the 5' UTR. We determined that the U107 and U144 pause signals are organized in a modular fashion containing distinct RNA hairpin, U-tract, and T-tract components. NusA-stimulated pausing was affected by hairpin strength and the U-tract sequence, whereas NusG-stimulated pausing was affected by hairpin strength and the T-tract sequence. We also determined that pausing at U107 results in increased TRAP-dependent termination in the 5' UTR, implying that NusA- and NusG-stimulated pausing participates in the trp operon attenuation mechanism by providing additional time for TRAP binding.

Original languageEnglish (US)
Article numbere00223-17
JournalJournal of bacteriology
Volume199
Issue number14
DOIs
StatePublished - Jul 1 2017

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

Fingerprint Dive into the research topics of 'Modular organization of the NusA- and NusG-stimulated RNA polymerase pause signal that participates in the Bacillus subtilis trp operon attenuation mechanism'. Together they form a unique fingerprint.

  • Cite this