title: Overview of CRISPR-Cas9 Biology.
abstract: Prokaryotes use diverse strategies to improve fitness in the face of different environmental threats and stresses, including those posed by mobile genetic elements (e.g., bacteriophages and plasmids). To defend against these elements, many bacteria and archaea use elegant, RNA-directed, nucleic acid-targeting adaptive restriction machineries called CRISPR -: Cas (CRISPR-associated) systems. While providing an effective defense against foreign genetic elements, these systems have also been observed to play critical roles in regulating bacterial physiology during environmental stress. Increasingly, CRISPR-Cas systems, in particular the Type II systems containing the Cas9 endonuclease, have been exploited for their ability to bind desired nucleic acid sequences, as well as direct sequence-specific cleavage of their targets. Cas9-mediated genome engineering is transcending biological research as a versatile and portable platform for manipulating genetic content in myriad systems. Here, we present a systematic overview of CRISPR-Cas history and biology, highlighting the revolutionary tools derived from these systems, which greatly expand the molecular biologists' toolkit.
authors.affiliation: Department of Microbiology and Immunology, Microbiology and Molecular Genetics Program, Emory University, Atlanta, Georgia 30329.|Emory Vaccine Center, Emory University, Atlanta, Georgia 30329.|Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329.
authors.forename: Hannah K
authors.initials: HK
authors.lastname: Ratner
authors.affiliation: Department of Microbiology and Immunology, Microbiology and Molecular Genetics Program, Emory University, Atlanta, Georgia 30329.|Emory Vaccine Center, Emory University, Atlanta, Georgia 30329.|Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Sampson
authors.affiliation: Emory Vaccine Center, Emory University, Atlanta, Georgia 30329.|Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329.|Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30329.
authors.forename: David S
authors.initials: DS
authors.lastname: Weiss
mesh_terms: D001105:Archaea / Q000201:enzymology* / Q000235:genetics*; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics*; D064113:CRISPR-Cas Systems; D018390:Gene Targeting / Q000379:methods; D022761:Gene Transfer, Horizontal; D020071:Interspersed Repetitive Sequences