Small non-coding regulatory RNAs in bacteria have been shown predominantly to be tightly regulated at the level of transcription initiation, and sRNAs that function by an antisense mechanism on trans-encoded target mRNAs have been predicted to act stoichiometrically; i.e.being destroyed in a 1:1 manner with the target RNA. Here, a novel mechanism for inactivation of a regulatory small RNA will be described. We found that the conserved MicM RNA, which silences the expression of the YbfM porin under most growth conditions, does not become destabilized by target mRNA overexpression, indicating that the sRNA acts catalytically rather than stoichiometrically. Furthermore, our regulatory studies suggested that control of micM expression is unlikely to operate at the level of transcription initiation. By employing a highlysensitive genetic screen we uncovered that induction of a trap mRNA leads to selective degradation of the small regulatory RNA molecule, thereby abolishing the sRNA-based silencing of its cognate target mRNA. That is, the uncovered target transcript regulates the sRNA, and not the reverse. This antisense regulation of an antisense RNA makes biological sense and is reminiscent of the regulation of microRNA activity through target mimicry that occurs in plant and mammalian cells.
|Periode||16. feb. 2010|
|Begivenhedstitel||31st Lorne Genome Conference 2010: null|