CRISPR interference: RNA-directed adaptive immunity in bacteria and archaea
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Updated: Jun 16, 2026

Selection-dependent and Independent Generation of CRISPR/Cas9-mediated Gene Knockouts in Mammalian Cells
Published on: June 16, 2017
Luciano A Marraffini1, Erik J Sontheimer
1Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA. l-marraffini@northwestern.edu
Abstract:
Sequence-directed genetic interference pathways control gene expression and preserve genome integrity in all kingdoms of life. The importance of such pathways is highlighted by the extensive study of RNA interference (RNAi) and related processes in eukaryotes. In many bacteria and most archaea, clustered, regularly interspaced short palindromic repeats (CRISPRs) are involved in a more recently discovered interference pathway that protects cells from bacteriophages and conjugative plasmids. CRISPR sequences provide an adaptive, heritable record of past infections and express CRISPR RNAs - small RNAs that target invasive nucleic acids. Here, we review the mechanisms of CRISPR interference and its roles in microbial physiology and evolution. We also discuss potential applications of this novel interference pathway.
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