title: CRISPR-mediated adaptive immune systems in bacteria and archaea.
abstract: Effective clearance of an infection requires that the immune system rapidly detects and neutralizes invading parasites while strictly avoiding self-antigens that would result in autoimmunity. The cellular machinery and complex signaling pathways that coordinate an effective immune response have generally been considered properties of the eukaryotic immune system. However, a surprisingly sophisticated adaptive immune system that relies on small RNAs for sequence-specific targeting of foreign nucleic acids was recently discovered in bacteria and archaea. Molecular vaccination in prokaryotes is achieved by integrating short fragments of foreign nucleic acids into a repetitive locus in the host chromosome known as a CRISPR (clustered regularly interspaced short palindromic repeat). Here we review the mechanisms of CRISPR-mediated immunity and discuss the ecological and evolutionary implications of these adaptive defense systems.
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel. rotem.sorek@weizmann.ac.il
authors.forename: Rotem
authors.initials: R
authors.lastname: Sorek
authors.forename: C Martin
authors.initials: CM
authors.lastname: Lawrence
authors.forename: Blake
authors.initials: B
authors.lastname: Wiedenheft
mesh_terms: D056704:Adaptive Immunity / Q000235:genetics*; D001105:Archaea / Q000235:genetics / Q000276:immunology*; D001419:Bacteria / Q000235:genetics / Q000276:immunology*; D055029:Inverted Repeat Sequences / Q000235:genetics* / Q000276:immunology; D019642:RNA, Archaeal / Q000235:genetics* / Q000276:immunology; D012329:RNA, Bacterial / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics* / Q000276:immunology
chemical_list: D019642:RNA, Archaeal; D012329:RNA, Bacterial