From Bacteriophage Defense Systems

To Novel Genetic Tools and Back
mercredi, 8 décembre 2021 - 11:30 am
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Personne-ressource: 
Dr. Eva Hemmer
Courriel: 
ehemmer@uOttawa.ca
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Abstract   The anti-bacteriophage defense system known as CRISPR-Cas has been engineered into powerful genetic tools. Our work has focused on the use of CRISPR-Cas systems to control gene expression in bacteria using Cas effectors modified to bind target DNA without introducing DNA breaks. The dCas9 protein can modulate gene expression by blocking transcription initiation or acting as a transcription roadblock. CRISPR-Cas tools can be further engineered to obtain fine-tuned control of gene expression or target multiple genes simultaneously. Several caveats in using these tools have also been revealed, including off-target effects and toxicity, making it important to understand the design rules of engineered CRISPR-Cas effectors in bacteria. Yet, CRISPR-Cas systems have found numerous applications in bacterial genetics in particular in high-throughput screens, which we have recently employed to investigate the evolution of gene essentiality in the E. coli species. This work led us to the unexpected discovery of horizontally transferred genes able to modulate the essentiality of core genes. Some of these genes include phage defense systems located within hotspots of genetic diversity carried by prophages and phage satellites.   Speaker Bio   Dr. David Bikard is a young investigator at the Institut Pasteur in the department of Microbiology where he started his group in 2014. David graduated from AgroParisTech and obtained his PhD from Paris Diderot University for his work performed at the Institut Pasteur on the integron bacterial recombination system. He then joined the laboratory of Luciano Marraffini at the Rockefeller University as a postdoctoral fellow where he started to work on CRISPR systems. David is interested in applying engineering principles to better understand and fight pathogenic bacteria.