J. Bacteriol., 07 1996, 4176-4181, Vol 178, No. 14
Copyright © 1996, American Society for Microbiology

Effects of H-NS and potassium glutamate on sigmaS- and sigma70-directed transcription in vitro from osmotically regulated P1 and P2 promoters of proU in Escherichia coli

K Rajkumari, S Kusano, A Ishihama, T Mizuno and J Gowrishankar
Centre for Cellular & Molecular Biology, Hyderabad, India.

We have used supercoiled DNA templates in this study to demonstrate that transcription in vitro from the P1 and P2 promoters of the osmoresponsive proU operon of Escherichia coli is preferentially mediated by the sigma(s) and sigma70-bearing RNA polymerase holoenzymes, respectively. Addition of potassium glutamate resulted in the activation of transcription from both P1 and P2 and also led to a pronounced enhancement of sigma(s) selectivity at the P1 promoter. Transcription from P2, and to a lesser extent from P1, was inhibited by the nucleoid protein H-NS but only in the absence of potassium glutamate. This study validates the existence of dual promoters with dual specificities for proU transcription. Our results also support the proposals that potassium, which is known to accumulate in cells grown at high osmolarity, is at least partially responsible for effecting the in vivo induction of proU transcription and that it does so through two mechanisms, directly by the activation of RNA polymerase and indirectly by the relief of repression imposed by H-NS.

This article has been cited by other articles:

• Laishram, R. S., Gowrishankar, J. (2007). Environmental regulation operating at the promoter clearance step of bacterial transcription. Genes Dev. 21: 1258-1272 [Abstract] [Full Text]  
• Shimada, T., Makinoshima, H., Ogawa, Y., Miki, T., Maeda, M., Ishihama, A. (2004). Classification and Strength Measurement of Stationary-Phase Promoters by Use of a Newly Developed Promoter Cloning Vector. J. Bacteriol. 186: 7112-7122 [Abstract] [Full Text]  
• Gowrishankar, J., Yamamoto, K., Subbarayan, P. R., Ishihama, A. (2003). In Vitro Properties of RpoS ({sigma}S) Mutants of Escherichia coli with Postulated N-Terminal Subregion 1.1 or C-Terminal Region 4 Deleted. J. Bacteriol. 185: 2673-2679 [Abstract] [Full Text]  
• Badaut, C., Williams, R., Arluison, V., Bouffartigues, E., Robert, B., Buc, H., Rimsky, S. (2002). The Degree of Oligomerization of the H-NS Nucleoid Structuring Protein Is Related to Specific Binding to DNA. J. Biol. Chem. 277: 41657-41666 [Abstract] [Full Text]  
• Rajkumari, K., Gowrishankar, J. (2002). An N-Terminally Truncated RpoS ({sigma}S) Protein in Escherichia coli Is Active In Vivo and Exhibits Normal Environmental Regulation Even in the Absence of rpoS Transcriptional and Translational Control Signals. J. Bacteriol. 184: 3167-3175 [Abstract] [Full Text]  
• Rajkumari, K., Gowrishankar, J. (2001). In Vivo Expression from the RpoS-Dependent P1 Promoter of the Osmotically Regulated proU Operon in Escherichia coli and Salmonella enterica Serovar Typhimurium: Activation by rho and hns Mutations and by Cold Stress. J. Bacteriol. 183: 6543-6550 [Abstract] [Full Text]  
• Berlyn, M. K. B. (1998). Linkage Map of Escherichia coli K-12, Edition 10: The Traditional Map. Microbiol. Mol. Biol. Rev. 62: 814-984 [Abstract] [Full Text]