Of the many examples of bacterial regulatory RNAs, CRISPR RNAs stand out as core components of adaptive immune systems called CRISPR-Cas systems. These systems rely on the CRISPR RNAs to recognize complementary nucleic acids from infecting foreign invaders, thereby enacting an immune response through the system’s effector nucleases to thwart the infection. Due to the programmable nature of the CRISPR RNAs, the effector nuclease can be directed to other nucleic acids, whether to direct DNA cutting as part of genome editing or to elicit collateral RNA cleavage as part of molecular diagnostics. My lab has been working at this interface, with goal of translating discoveries into new and improved technologies. In this talk, I will focus on my group’s work harnessing a unique discovery—some CRISPR-Cas systems converting cellular RNAs into CRISPR RNAs—as the basis of a suite of technologies for multiplexed molecular diagnostics and RNA recording in live cells. These examples will highlight the technological potential of CRISPR RNAs as one example of bacterial regulatory RNAs and how to proceed from exciting discovery to versatile technologies.
Carmen BUCHRIESER, Institut Pasteur, Paris : Transkingdom signalling via Legionella pneumophila small regulatory RNAs
Of the many examples of bacterial regulatory RNAs, CRISPR RNAs stand out as core components of adaptive immune systems called CRISPR-Cas systems. These systems rely on the CRISPR RNAs to recognize complementary nucleic acids from infecting foreign invaders, thereby enacting an immune response through the system’s effector nucleases to thwart the infection. Due to the programmable nature of the CRISPR RNAs, the effector nuclease can be directed to other nucleic acids, whether to direct DNA cutting as part of genome editing or to elicit collateral RNA cleavage as part of molecular diagnostics. My lab has been working at this interface, with goal of translating discoveries into new and improved technologies. In this talk, I will focus on my group’s work harnessing a unique discovery—some CRISPR-Cas systems converting cellular RNAs into CRISPR RNAs—as the basis of a suite of technologies for multiplexed molecular diagnostics and RNA recording in live cells. These examples will highlight the technological potential of CRISPR RNAs as one example of bacterial regulatory RNAs and how to proceed from exciting discovery to versatile technologies.
Jonathan JAGODNIK, CNRS UMR8261/UP-Cité, IBPC, Paris : The global mapping of 30S binding in E. coli unravels a wide variety of non-canonical 30S-mRNA interactions
Translation initiation is a key step of gene expression in all living organisms. As the limiting step of translation, it is also subjected to many regulatory events. In bacteria, it typically involves the binding of the 30S subunit of the ribosome to the mRNA, through recognition of the mRNA Shine-Dalgarno (SD) and AUG start codon. However, the process through which 30S finds translation initiation regions, for instance with very degenerated SD sequences or within long mRNA 5’UTRs remains elusive. To investigate this, we adapted to bacteria the RiboSeq-derived method of translation complex profiling (TCPseq), originally developed in eukarya. TCPseq provided the first map of 30S-covered mRNA regions in E. coli, identifying >400 non-canonical 30S binding sites, as well as many unexpected 30S binding patterns. These results pave the way for the discovery of non-canonical translation initiation mechanisms and reshape our understanding of ribosome binding in bacteria.
