Scan

Title: Regulating the Terminator: Salmonella SraL sRNA protects rho transcript from the action of its own protein

Speaker: Inês Silva

Affiliation: Control of Gene Expression Lab, ITQB NOVA

Abstract:

RNAs are important effectors in the process of gene expression. In bacteria, the levels of the transcripts must be rapidly adjusted in response to constantly changing environmental demands. Small non-coding RNAs (sRNAs) can lead to fast changes in gene expression since they can directly modulate the expression and/or stability of their RNA or protein targets.

Transcription termination is also a critical step in the control of gene expression. One of the major termination mechanisms is mediated by Rho factor that dissociates the complex mRNA-DNA-RNA polymerase upon binding with RNA polymerase. Rho promotes termination at the end of operons, but it can also terminate transcription within leader regions, performing regulatory functions and avoiding pervasive transcription. Transcription of rho is autoregulated through a Rho-dependent attenuation in the leader region of the transcript. We have recently included an additional player in this pathway.

We have shown that the rho transcript directly interacts with the small non-coding RNA SraL. Using bioinformatic, and in vivo and in vitro experimental analyses, SraL was shown to base pair with the 5'-UTR of rho mRNA upregulating its expression in several growth conditions. This base pairing was shown to prevent the action of Rho over its own message. We propose a new model that contemplates the action of Salmonella SraL sRNA in the protection of rho mRNA from premature transcription termination by Rho. Since the interaction region between both RNAs corresponds to a very-well-conserved sequence, it is plausible to admit that this regulation also occurs in other enterobacteria.