Fang L, Xia B, Inouye M
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
FEMS Microbiol Lett. 1999 Jul 1;176(1):39-43. doi: 10.1111/j.1574-6968.1999.tb13639.x.
The gene for CspA, the major cold-shock protein in Escherichia coli, is tightly regulated at both optimal and low temperatures. While CspA is drastically induced after temperature downshift, it is hardly detectable at 37 degrees C. Here we demonstrate that the deletion of parts of the 5'-untranslated region (5'-UTR) of the cspA mRNA results in constitutive expression of CspA at 37 degrees C. By analyzing the amounts and the stabilities of the mRNAs produced from the deletion constructs, we rule out the possibility that the CspA production is due to the stabilization of the mutant mRNAs. We propose that significant premature termination or pausing occurs during the transcription of the unusually long 5'-UTR of the cspA mRNA at 37 degrees C, which represents a new mechanism that contributes to the tight repression of CspA production at higher temperature.
大肠杆菌中主要的冷休克蛋白CspA的基因在最适温度和低温下均受到严格调控。虽然温度下降后CspA会大量诱导表达，但在37℃时几乎检测不到。在此我们证明，缺失cspA mRNA 5'-非翻译区（5'-UTR）的部分区域会导致CspA在37℃时组成型表达。通过分析缺失构建体产生的mRNA的量和稳定性，我们排除了CspA产生是由于突变mRNA稳定化的可能性。我们提出，在37℃时，cspA mRNA异常长的5'-UTR转录过程中会发生显著的过早终止或暂停，这代表了一种有助于在较高温度下严格抑制CspA产生的新机制。
