@article{luo_mullis_leenay_beisel_2015, title={Repurposing endogenous type I CRISPR-Cas systems for programmable gene repression}, volume={43}, ISSN={["1362-4962"]}, DOI={10.1093/nar/gku971}, abstractNote={CRISPR-Cas systems have shown tremendous promise as heterologous tools for genome editing and transcriptional regulation. Because these RNA-directed immune systems are found in most prokaryotes, an opportunity exists to harness the endogenous systems as convenient tools in these organisms. Here, we report that the Type I-E CRISPR-Cas system in Escherichia coli can be co-opted for programmable transcriptional repression. We found that deletion of the signature cas3 gene converted this immune system into a programmable gene regulator capable of reversible gene silencing of heterologous and endogenous genes. Targeting promoter regions yielded the strongest repression, whereas targeting coding regions showed consistent strand bias. Furthermore, multi-targeting CRISPR arrays could generate complex phenotypes. This strategy offers a simple approach to convert many endogenous Type I systems into transcriptional regulators, thereby expanding the available toolkit for CRISPR-mediated genetic control while creating new opportunities for genome-wide screens and pathway engineering.}, number={1}, journal={NUCLEIC ACIDS RESEARCH}, author={Luo, Michelle L. and Mullis, Adam S. and Leenay, Ryan T. and Beisel, Chase L.}, year={2015}, month={Jan}, pages={674–681} }