Stress-Induced Changes in Transcript Stability

Regulation of gene expression in bacteria has been studied mainly at the transcriptional level. However, it has now become clear that a significant part of the control is carried out at the posttranscriptional levels. Recently, several regulatory mechanisms have been shown to act at the level of transcript stability. These control systems are especially important upon exposure to stress conditions, when a rapid and robust adaptation is essential. Here we focus on the stress-induced changes in transcript stability, mainly these involving RNA chaperones. We will discuss the effect of RNA chaperones on stabilizing transcripts of the general stress response genes during stress, and the converse effect of RNA chaperones on reducing the stability of heat shock gene transcripts following elevation of temperature. The general model that evolves from these data is that two chaperones - CspC and CspE - re involved in modulating transcript stability of specific stress response genes. CspE acts as a "housekeeping RNA chaperone," while CspC modulates transcript stability upon exposure to environmental stress.