TY  - BOOK
AU  - Wiedenheft,B.
AU  - Lander,G.C.
AU  - Zhou,K.
AU  - Jore,M.M.
AU  - Brouns,S.J.J.
AU  - Van Der Oost,J.
AU  - Doudna,J.A.
AU  - Doudna,J.A.
TI  - Structures of the RNA-guided surveillance complex from a bacterial immune system
KW  - NUCLEIC ACID
KW  - PROTEIN CASA
KW  - PROTEIN CASB
KW  - PROTEIN CASC
KW  - PROTEIN CASD
KW  - PROTEIN CASE
KW  - RIBONUCLEOPROTEIN
KW  - RNA
KW  - UNCLASSIFIED DRUG
N2  - Bacteria and archaea acquire resistance to viruses and plasmids by integrating short fragments of foreign DNA into clustered regularly interspaced short palindromic repeats (CRISPRs). These repetitive loci maintain a genetic record of all prior encounters with foreign transgressors. CRISPRs are transcribed and the long primary transcript is processed into a library of short CRISPR-derived RNAs (crRNAs)that contain a unique sequence complementary to a foreign nucleic-acid challenger. In Escherichia coli, crRNAs are incorporated into a multisubunit surveillance complex called Cascade (CRISPR-associated complex for antiviral defence), which is required for protection against bacteriophages. Here we use cryo-electron microscopy to determine the subnanometre structures of Cascade before and after binding to a target sequence. These structures reveal a sea-horse-shaped architecture in which the crRNA is displayed along a helical arrangement of protein subunits that protect the crRNA from degradation while maintaining its availability for base pairing. Cascade engages invading nucleic acids through high-affinity base-pairing interactions near the 5-2 end of the crRNA. Base pairing extends along the crRNA, resulting in a series of short helical segments that trigger a concerted conformational change. This conformational rearrangement may serve as a signal that recruits a trans-acting nuclease (Cas3)for destruction of invading nucleic-acid sequences
UR  - https://drive.google.com/file/d/127a8PBRy3Qyv2txdjpG_7COpneyzf-uE/view?usp=drivesdk
ER  -