title: Mechanism of spacer integration links the CRISPR/Cas system to transposition as a form of mobile DNA.
abstract: It has recently become clear that many bacterial and archaeal species possess adaptive immune systems. These are typified by multiple copies of DNA sequences known as clustered regularly interspaced short palindromic repeats (CRISPRs). These CRISPR repeats are the sites at which short spacers containing sequences of previously encountered foreign DNA are integrated, and the spacers serve as the molecular memory of previous invaders. In vivo work has demonstrated that two CRISPR-associated proteins - Cas1 and Cas2 - are required for spacer integration, but the mechanism by which this is accomplished remained unclear. Here we review a recent paper describing the in vitro reconstitution of CRISPR spacer integration using purified Cas1 and Cas2 and place the results in context of similar DNA transposition reactions and the crystal structure of the Cas1/Cas2 complex.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 5 Center Dr., Bethesda, MD 20892 USA.
authors.forename: Fred
authors.initials: F
authors.lastname: Dyda
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 5 Center Dr., Bethesda, MD 20892 USA.
authors.forename: Alison B
authors.initials: AB
authors.lastname: Hickman
keywords: Adaptive immunity; CRISPR/Cas; Cas1 nuclease protein; DNA transposition; Integrase