title: RNA-activated DNA cleavage by the Type III-B CRISPR-Cas effector complex.
abstract: The CRISPR (clustered regularly interspaced short palindromic repeat) system is an RNA-guided immune system that protects prokaryotes from invading genetic elements. This system represents an inheritable and adaptable immune system that is mediated by multisubunit effector complexes. In the Type III-B system, the Cmr effector complex has been found to cleave ssRNA in vitro. However, in vivo, it has been implicated in transcription-dependent DNA targeting. We show here that the Cmr complex from Thermotoga maritima can cleave an ssRNA target that is complementary to the CRISPR RNA. We also show that binding of a complementary ssRNA target activates an ssDNA-specific nuclease activity in the histidine-aspartate (HD) domain of the Cmr2 subunit of the complex. These data suggest a mechanism for transcription-coupled DNA targeting by the Cmr complex and provide a unifying mechanism for all Type III systems.
authors: Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors: Michael A
authors: MA
authors: Estrella
authors: Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors: Fang-Ting
authors: FT
authors: Kuo
authors: Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors: Scott
authors: S
authors: Bailey
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D064113:CRISPR-Cas Systems / Q000502:physiology*; D053837:DNA Cleavage; D003851:Deoxyribonucleases / Q000378:metabolism; D004789:Enzyme Activation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000378:metabolism; D020124:Thermotoga maritima / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D003851:Deoxyribonucleases
keywords: CMR; CRISPR–Cas; RAMP; RNA; nuclease