Gene regulation by engineered CRISPR-Cas systems

The clustered regularly interspaced short palindromic repeat (CRISPR) arrays and their CRISPR associated (Cas) proteins constitute adaptive immune systems in bacteria and archaea that provide protection from bacteriophages, plasmids and other mobile genetic elements (MGEs). Recently, the ability to direct these systems to DNA in a sequence-specific manner has led to the emergence of new technologies for engineered gene regulation in bacteria and eukaryotes. These systems have the potential to enable facile high-throughput functional genomics studies aimed at identifying gene function and will be a crucial tool for synthetic biology. Here, we review the recent engineering of these systems for controlling gene expression.