Promoter-independent cold-shock induction of cspA and its derepression at 37°C by mRNA stabilization |
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Authors: | Li Fang,Weining Jiang,Weonhye Bae,& Masayori Inouye |
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Affiliation: | Department of Biochemistry, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854, USA. |
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Abstract: | The gene for CspA, the major cold-shock protein of Escherichia coli is known to be dramatically induced upon temperature downshift. Here, we report that three-base substitutions around the Shine–Dalgarno sequence in the 159-base 5'-untranslated region of the cspA mRNA stabilizes the mRNA 150-fold, resulting in constitutive expression of cspA at 37°C. This stabilization was found to be at least partially due to resistance against RNase E degradation. The cold-shock induction of cspA was also achieved by exchanging its promoter with the non-cold-shock lpp promoter. The results presented indicate that the cspA gene is efficiently transcribed even at 37°C. However, the translation of the cspA mRNA is blocked because of its extreme instability at 37°C. The presented results also demonstrate that the cspA gene is constitutively transcribed at all temperatures; however, its expression at 37°C is prevented by destabilizing its mRNA. |
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