This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhang, H. Articles by Switzer, R. L. Search for Related Content PubMed PubMed Citation Articles by Zhang, H. Articles by Switzer, R. L.

Transcriptional Pausing in the Bacillus subtilis pyr Operon In Vitro: a Role in Transcriptional Attenuation?

Department of Biochemistry, University of Illinois, Urbana, Illinois 61801

Received 24 February 2003/ Accepted 19 May 2003

The genes encoding the enzymes of pyrimidine nucleotide biosynthesis (pyr genes) are regulated in Bacillus subtilis and many other bacterial species by transcriptional attenuation. When UMP or UTP is bound to the PyrR regulatory protein, it binds to pyr mRNA at specific sequences and secondary structures in the RNA. Binding to this site prevents formation of an antiterminator stem-loop in the RNA and permits formation of a downstream terminator, leading to reduced expression of the pyr genes lying downstream from the terminator. The functioning of several other transcriptional attenuation systems has been shown to involve transcriptional pausing; this observation stimulated us to use single-round transcription of pyr genes to test for formation of paused transcripts in vitro. Using templates with each of the three known B. subtilis pyr attenuation sites, we identified one major pause site in each in which the half-life of the paused transcript was increased four- to sixfold by NusA. In each case pausing at the NusA-stimulated site prevented formation of a complete antiterminator stem-loop, while it resulted in increased time for a PyrR binding loop to form and for PyrR to bind to this loop. Thus, the pausing detected in vitro is potentially capable of playing a role in establishing the correct timing for pyr attenuation in vivo. With two of three pyr templates the combination of NusA with PyrR markedly stimulated termination of transcription at the normal termination sites. This suggests that NusA, by stabilizing pausing, plays a role in termination of pyr transcription in vivo.

This article has been cited by other articles:

• Turnbough, C. L. Jr., Switzer, R. L. (2008). Regulation of Pyrimidine Biosynthetic Gene Expression in Bacteria: Repression without Repressors. Microbiol. Mol. Biol. Rev. 72: 266-300 [Abstract] [Full Text]  
• Nicoloff, H., Elagoz, A., Arsene-Ploetze, F., Kammerer, B., Martinussen, J., Bringel, F. (2005). Repression of the pyr Operon in Lactobacillus plantarum Prevents Its Ability To Grow at Low Carbon Dioxide Levels. J. Bacteriol. 187: 2093-2104 [Abstract] [Full Text]  
• Grundy, F. J., Henkin, T. M. (2004). Kinetic Analysis of tRNA-Directed Transcription Antitermination of the Bacillus subtilis glyQS Gene In Vitro. J. Bacteriol. 186: 5392-5399 [Abstract] [Full Text]