title: Invasive DNA, chopped and in the CRISPR.
abstract: In this issue of Structure, Wiedenheft et al. describe the structure and activity of Cas1, the only protein associated with all CRISPR loci. Cas1 is a metal-dependent deoxyribonuclease, consistent with a role in the adaptation phase of CRISPR immunity against invading nucleic acids.
authors.affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA.
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Marraffini
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Sontheimer
mesh_terms: D001435:Bacteriophages / Q000276:immunology; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D003851:Deoxyribonucleases / Q000737:chemistry / Q000378:metabolism*; D007109:Immunity; D018448:Models, Immunological; D011506:Proteins / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D011506:Proteins; D003851:Deoxyribonucleases