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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. 2001 Nov; 183(22):6543-50.JB

Abstract

Unlike the sigma(70)-controlled P2 promoter for the osmotically regulated proU operon of Escherichia coli and Salmonella enterica serovar Typhimurium, the sigma(s)-controlled P1 promoter situated further upstream appears not to contribute to expression of the proU structural genes under ordinary growth conditions. For S. enterica proU P1, there is evidence that promoter crypticity is the result of a transcription attenuation phenomenon which is relieved by the deletion of a 22-base C-rich segment in the transcript. In this study, we have sought to identify growth conditions and trans-acting mutations which activate in vivo expression from proU P1. The cryptic S. enterica proU P1 promoter was activated, individually and additively, in a rho mutant (which is defective in the transcription termination factor Rho) as well as by growth at 10 degrees C. The E. coli proU P1 promoter was also cryptic in constructs that carried 1.2 kb of downstream proU sequence, and in these cases activation of in vivo expression was achieved either by a rho mutation during growth at 10 degrees C or by an hns null mutation (affecting the nucleoid protein H-NS) at 30 degrees C. The rho mutation had no effect at either 10 or 30 degrees C on in vivo expression from two other sigma(s)-controlled promoters tested, those for osmY and csiD. In cells lacking the RNA-binding regulator protein Hfq, induction of E. coli proU P1 at 10 degrees C and by hns mutation at 30 degrees C was still observed, although the hfq mutation was associated with a reduction in the absolute levels of P1 expression. Our results suggest that expression from proU P1 is modulated both by nucleoid structure and by Rho-mediated transcription attenuation and that this promoter may be physiologically important for proU operon expression during low-temperature growth.

Authors+Show Affiliations

Centre for Cellular and Molecular Biology, Hyderabad 500 007, India.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11673423

Citation

Rajkumari, K, and J Gowrishankar. "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." Journal of Bacteriology, vol. 183, no. 22, 2001, pp. 6543-50.
Rajkumari K, Gowrishankar J. 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. 2001;183(22):6543-50.
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. Journal of Bacteriology, 183(22), 6543-50.
Rajkumari K, Gowrishankar J. 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. 2001;183(22):6543-50. PubMed PMID: 11673423.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - 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. AU - Rajkumari,K, AU - Gowrishankar,J, PY - 2001/10/24/pubmed PY - 2002/1/5/medline PY - 2001/10/24/entrez SP - 6543 EP - 50 JF - Journal of bacteriology JO - J Bacteriol VL - 183 IS - 22 N2 - Unlike the sigma(70)-controlled P2 promoter for the osmotically regulated proU operon of Escherichia coli and Salmonella enterica serovar Typhimurium, the sigma(s)-controlled P1 promoter situated further upstream appears not to contribute to expression of the proU structural genes under ordinary growth conditions. For S. enterica proU P1, there is evidence that promoter crypticity is the result of a transcription attenuation phenomenon which is relieved by the deletion of a 22-base C-rich segment in the transcript. In this study, we have sought to identify growth conditions and trans-acting mutations which activate in vivo expression from proU P1. The cryptic S. enterica proU P1 promoter was activated, individually and additively, in a rho mutant (which is defective in the transcription termination factor Rho) as well as by growth at 10 degrees C. The E. coli proU P1 promoter was also cryptic in constructs that carried 1.2 kb of downstream proU sequence, and in these cases activation of in vivo expression was achieved either by a rho mutation during growth at 10 degrees C or by an hns null mutation (affecting the nucleoid protein H-NS) at 30 degrees C. The rho mutation had no effect at either 10 or 30 degrees C on in vivo expression from two other sigma(s)-controlled promoters tested, those for osmY and csiD. In cells lacking the RNA-binding regulator protein Hfq, induction of E. coli proU P1 at 10 degrees C and by hns mutation at 30 degrees C was still observed, although the hfq mutation was associated with a reduction in the absolute levels of P1 expression. Our results suggest that expression from proU P1 is modulated both by nucleoid structure and by Rho-mediated transcription attenuation and that this promoter may be physiologically important for proU operon expression during low-temperature growth. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/11673423/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_ L2 - https://journals.asm.org/doi/10.1128/JB.183.22.6543-6550.2001?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -