This Article Full Text (PDF) Other Versions of this Article: JB.01658-06v1 189/5/1866    most recent 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 Barnett, T. C. Articles by Scott, J. R. Search for Related Content PubMed PubMed Citation Articles by Barnett, T. C. Articles by Scott, J. R.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01658-06
Copyright (c) 2006, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

The Role of mRNA Stability in Growth Phase Regulation of Gene Expression in the Group A Streptococcus

Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322

^* To whom correspondence should be addressed. Email: scott{at}microbio.emory.edu.

	Abstract

The impressive disease spectrum of Streptococcus pyogenes (the group A streptococcus; GAS) is believed to be determined by its ability to modify gene expression in response to environmental stimuli. Virulence gene expression is controlled tightly by several different transcriptional regulators in this organism. In addition, expression of most, if not all, GAS genes is determined by a global mechanism dependent on growth phase. To begin an analysis of growth phase regulation, we compared the transcriptome two hours into stationary phase to that in late exponential phase of a serotype M3 GAS strain. We identified the arc transcript as more abundant in stationary phase in addition to the sag and sda transcripts that had been previously identified. We found that in stationary phase, the stability of sagA, sda and arcT transcripts increased dramatically. We found that polynucleotide phosphorylase (PNPase encoded by pnpA) is rate-limiting for decay of sagA and sda transcripts in late exponential phase, since the stability of these mRNAs was greater in a pnpA mutant, while stability of control mRNAs was unaffected by this mutation. Complementation restored the wild type decay rate. Furthermore, in a pnpA mutant, the sagA mRNA appeared to be full length, as determined by Northern hybridization. It seems likely that mRNAs abundant in stationary phase are insensitive to the normal decay enzyme(s) and instead require PNPase for this process. It is possible that PNPase activity is limited in stationary phase, allowing persistence of these important virulence factor transcripts at this phase of growth.

This article has been cited by other articles:

• Biswas, I., Jha, J. K., Fromm, N. (2008). Shuttle expression plasmids for genetic studies in Streptococcus mutans. Microbiology 154: 2275-2282 [Abstract] [Full Text]  
• Erova, T. E., Kosykh, V. G., Fadl, A. A., Sha, J., Horneman, A. J., Chopra, A. K. (2008). Cold Shock Exoribonuclease R (VacB) Is Involved in Aeromonas hydrophila Pathogenesis. J. Bacteriol. 190: 3467-3474 [Abstract] [Full Text]  
• Andrade, J. M., Arraiano, C. M. (2008). PNPase is a key player in the regulation of small RNAs that control the expression of outer membrane proteins. RNA 14: 543-551 [Abstract] [Full Text]  
• Zahner, D., Scott, J. R. (2008). SipA Is Required for Pilus Formation in Streptococcus pyogenes Serotype M3. J. Bacteriol. 190: 527-535 [Abstract] [Full Text]