title: Structural basis for CRISPR RNA-guided DNA recognition by Cascade.
abstract: The CRISPR (clustered regularly interspaced short palindromic repeats) immune system in prokaryotes uses small guide RNAs to neutralize invading viruses and plasmids. In Escherichia coli, immunity depends on a ribonucleoprotein complex called Cascade. Here we present the composition and low-resolution structure of Cascade and show how it recognizes double-stranded DNA (dsDNA) targets in a sequence-specific manner. Cascade is a 405-kDa complex comprising five functionally essential CRISPR-associated (Cas) proteins (CasA(1)B(2)C(6)D(1)E(1)) and a 61-nucleotide CRISPR RNA (crRNA) with 5'-hydroxyl and 2',3'-cyclic phosphate termini. The crRNA guides Cascade to dsDNA target sequences by forming base pairs with the complementary DNA strand while displacing the noncomplementary strand to form an R-loop. Cascade recognizes target DNA without consuming ATP, which suggests that continuous invader DNA surveillance takes place without energy investment. The structure of Cascade shows an unusual seahorse shape that undergoes conformational changes when it binds target DNA.
authors: Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands.
authors: Matthijs M
authors: MM
authors: Jore
authors: Magnus
authors: M
authors: Lundgren
authors: Esther
authors: E
authors: van Duijn
authors: Jelle B
authors: JB
authors: Bultema
authors: Edze R
authors: ER
authors: Westra
authors: Sakharam P
authors: SP
authors: Waghmare
authors: Blake
authors: B
authors: Wiedenheft
authors: Umit
authors: U
authors: Pul
authors: Reinhild
authors: R
authors: Wurm
authors: Rolf
authors: R
authors: Wagner
authors: Marieke R
authors: MR
authors: Beijer
authors: Arjan
authors: A
authors: Barendregt
authors: Kaihong
authors: K
authors: Zhou
authors: Ambrosius P L
authors: AP
authors: Snijders
authors: Mark J
authors: MJ
authors: Dickman
authors: Jennifer A
authors: JA
authors: Doudna
authors: Egbert J
authors: EJ
authors: Boekema
authors: Albert J R
authors: AJ
authors: Heck
authors: John
authors: J
authors: van der Oost
authors: Stan J J
authors: SJ
authors: Brouns
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000737:chemistry*; D004926:Escherichia coli / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D013329:Structure-Activity Relationship; D058727:RNA, Small Untranslated
chemical_list: C000605812:Cse1 protein, E coli; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012261:Ribonucleoproteins; D004247:DNA; D058727:RNA, Small Untranslated