Direct and indirect control of Rho-dependent transcription termination by theEscherichia coli lysCriboswitch

Abstract

Bacterial riboswitches are molecular structures that play a crucial role in controlling gene expression to maintain cellular balance. TheEscherichia coli lysCriboswitch has been previously shown to regulate gene expression through translation initiation and mRNA decay. Recent research suggests thatlysCgene expression is also influenced by Rho-dependent transcription termination. Through a series of in silico, in vitro, and in vivo experiments, we provide experimental evidence that thelysCriboswitch directly and indirectly modulates Rho transcription termination. Our study demonstrates that Rho-dependent transcription termination plays a significant role in the cotranscriptional regulation oflysCexpression. Together with previous studies, our work suggests thatlysCexpression is governed by a lysine-sensing riboswitch that regulates translation initiation, transcription termination, and mRNA degradation. Notably, both Rho and RNase E target the same region of the RNA molecule, implying that RNase E may degrade Rho-terminated transcripts, providing a means to selectively eliminate these incomplete messenger RNAs. Overall, this study sheds light on the complex regulatory mechanisms used by bacterial riboswitches, emphasizing the role of transcription termination in the control of gene expression and mRNA stability.