Fang L, Jiang W, Bae W, Inouye M
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
Mol Microbiol. 1997 Jan;23(2):355-64. doi: 10.1046/j.1365-2958.1997.2351592.x.
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 degrees 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 Ipp promoter. The results presented indicate that the cspA gene is efficiently transcribed even at 37 degrees C. However, the translation of the cspA mRNA is blocked because of its extreme instability at 37 degrees C. The presented results also demonstrate that the cspA gene is constitutively transcribed at all temperatures; however, its expression at 37 degrees C is prevented by destabilizing its mRNA.
已知大肠杆菌主要冷休克蛋白CspA的基因在温度下降时会被显著诱导。在此，我们报告，cspA mRNA 159个碱基的5'非翻译区中，围绕Shine-Dalgarno序列的三个碱基替换使mRNA稳定了150倍，导致cspA在37℃时组成型表达。发现这种稳定性至少部分归因于对RNase E降解的抗性。通过将cspA的启动子与非冷休克Ipp启动子交换，也实现了cspA的冷休克诱导。给出的结果表明，即使在37℃时，cspA基因也能有效转录。然而，由于cspA mRNA在37℃时极度不稳定，其翻译被阻断。给出的结果还表明，cspA基因在所有温度下都组成型转录；然而，在37℃时其mRNA的不稳定阻止了它的表达。
