title: RNA activation-independent DNA targeting of the Type III CRISPR-Cas system by a Csm complex.
abstract: The CRISPR-Cas system is an adaptive and heritable immune response that destroys invading foreign nucleic acids. The effector complex of the Type III CRISPR-Cas system targets RNA and DNA in a transcription-coupled manner, but the exact mechanism of DNA targeting by this complex remains elusive. In this study, an effector Csm holocomplex derived fromThermococcus onnurineusis reconstituted with a minimalistic combination of Csm1121334151, and shows RNA targeting and RNA-activated single-stranded DNA (ssDNA) targeting activities. Unexpectedly, in the absence of an RNA transcript, it cleaves ssDNA containing a sequence complementary to the bound crRNA guide region in a manner dependent on the HD domain of the Csm1 subunit. This nuclease activity is blocked by a repeat tag found in the host CRISPR loci. The specific cleavage of ssDNA without a target RNA suggests a novel ssDNA targeting mechanism of the Type III system, which could facilitate the efficient and complete degradation of foreign nucleic acids.
authors.affiliation: Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
authors.forename: Kwang-Hyun
authors.initials: KH
authors.lastname: Park
authors.affiliation: Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
authors.forename: Yan
authors.initials: Y
authors.lastname: An
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST) Institute for the BioCentury, Daejeon, South Korea.|Department of Biosciences and Nutrition, Karolinska Institute, Huddinge, Sweden.|School of Technology and Health, KTH Royal Institute of Technology, Huddinge, Sweden.
authors.forename: Tae-Yang
authors.initials: TY
authors.lastname: Jung
authors.affiliation: Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
authors.forename: In-Young
authors.initials: IY
authors.lastname: Baek
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST) Institute for the BioCentury, Daejeon, South Korea.
authors.forename: Haemin
authors.initials: H
authors.lastname: Noh
authors.affiliation: Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.|Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST) Institute for the BioCentury, Daejeon, South Korea.
authors.forename: Woo-Chan
authors.identifier: 0000-0002-9432-2363
authors.initials: WC
authors.lastname: Ahn
authors.affiliation: Department of Biosciences and Nutrition, Karolinska Institute, Huddinge, Sweden.|School of Technology and Health, KTH Royal Institute of Technology, Huddinge, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Hebert
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST) Institute for the BioCentury, Daejeon, South Korea.
authors.forename: Ji-Joon
authors.identifier: 0000-0001-7120-6311
authors.initials: JJ
authors.lastname: Song
authors.affiliation: Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea.
authors.forename: Jeong-Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST) Institute for the BioCentury, Daejeon, South Korea bhoh@kaist.ac.kr ejwoo@kribb.re.kr.
authors.forename: Byung-Ha
authors.initials: BH
authors.lastname: Oh
authors.affiliation: Disease Target Structure Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea bhoh@kaist.ac.kr ejwoo@kribb.re.kr.|Department of Analytical Bioscience, University of Science and Technology, Daejeon, South Korea.
authors.forename: Eui-Jeon
authors.identifier: 0000-0001-6983-0270
authors.initials: EJ
authors.lastname: Woo
mesh_terms: D019843:Archaeal Proteins / Q000378:metabolism; D064113:CRISPR-Cas Systems; D004277:DNA, Single-Stranded / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D019712:Thermococcus / Q000235:genetics
chemical_list: D019843:Archaeal Proteins; D004277:DNA, Single-Stranded; D012313:RNA; D003851:Deoxyribonucleases
keywords: 
  CRISPR
  ; 
  Thermococcus onnurineus
  ; Csm complex; DNase; RNase