1Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, CV4 7AL Coventry, UK
2Institute of Systems and Synthetic Biology, CNRS-Université d’Évry Val-d’Essonne, 91000 Évry, France
3Instituto de Biología Molecular y Celular de Plantas, CSIC-Universidad Politécnica de Valencia, 46022 Valencia, Spain
4Institute for Integrative Systems Biology (I2SysBio), CSIC-Universitat de València, 46980 Paterna, Spain
| Received 13 Jun 2020 |
Accepted 17 Aug 2020 |
Published 14 Sep 2020 |
RNAs of different shapes and sizes, natural or synthetic, can regulate gene expression in prokaryotes and eukaryotes. Circular RNAs have recently appeared to be more widespread than previously thought, but their role in prokaryotes remains elusive. Here, by inserting a riboregulatory sequence within a group I permuted intron-exon ribozyme, we created a small noncoding RNA that self-splices to produce a circular riboregulator in Escherichia coli. We showed that the resulting riboregulator can trans-activate gene expression by interacting with a cis-repressed messenger RNA. We characterized the system with a fluorescent reporter and with an antibiotic resistance marker, and we modeled this novel posttranscriptional mechanism. This first reported example of a circular RNA regulating gene expression in E. coli adds to an increasing repertoire of RNA synthetic biology parts, and it highlights that topological molecules can play a role in the case of prokaryotic regulation.
