Studies on the expression of 6S RNA from E. coli: involvement of regulators important for stress and growth adaptation
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Thomas Neußer
Abstract
The small bacterial 6S RNA has been recognized as a transcriptional regulator, facilitating the transition from exponential to stationary growth phase by preferentially inhibiting Eσ70 RNA polymerase holoenzyme transcription. Consistent with this function, the cellular concentration of 6S RNA increases with stationary phase. We have studied the underlying mechanisms responsible for the growth phase-dependent differences in 6S RNA concentration. To this aim, we have analyzed the effects of the typical bacterial growth phase and stress regulators FIS, H-NS, LRP and StpA on 6S RNA expression. Measurements of 6S RNA accumulation in strains deficient in each one of these proteins support their contribution as potential regulators. Specific binding of the four proteins to DNA fragments containing 6S RNA promoters was demonstrated by gel retardation and DNase I footprinting. Moreover, in vitro transcription analysis with both RNA polymerase holoenzymes, Eσ70 and Eσ38, demonstrated a direct inhibition of 6S RNA transcription by H-NS, StpA and LRP, while FIS seems to act as a dual regulator. In vitro transcription in the presence of ppGpp indicates that 6S RNA promoters are not stringently regulated. Our results underline that regulation of 6S RNA transcription depends on a complex network, involving a set of bacterial regulators with general importance in the adaptation to changing growth conditions.
©2008 by Walter de Gruyter Berlin New York
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Artikel in diesem Heft
- Highlight: Oxidative Stress and Senescence
- Regulation of proteasome-mediated protein degradation during oxidative stress and aging
- Cellular responses to reactive oxygen species-induced DNA damage and aging
- Sirt1 protects the heart from aging and stress
- Klotho as a regulator of oxidative stress and senescence
- Posttranscriptional gene regulation by RNA-binding proteins during oxidative stress: implications for cellular senescence
- Potential biomarkers of ageing
- Increased molecular damage and heterogeneity as the basis of aging
- Modulation of longevity-associated genes by estrogens or phytoestrogens
- FoxO transcription factors in oxidative stress response and ageing – a new fork on the way to longevity?
- Studies on the expression of 6S RNA from E. coli: involvement of regulators important for stress and growth adaptation
- New biological activity against phospholipase A2 by Turmerin, a protein from Curcuma longa L.
- Regulation of the expression of components of the exocytotic machinery of insulin-secreting cells by microRNAs
- Kinetic properties of cathepsin D and BACE 1 indicate the need to search for additional β-secretase candidate(s)
