RT Journal Article
SR Electronic
T1 Structure reveals mechanism of CRISPR RNA-guided nuclease recruitment and anti-CRISPR viral mimicry
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 453720
DO 10.1101/453720
A1 MaryClare F. Rollins
A1 Saikat Chowdhury
A1 Joshua Carter
A1 Sarah M. Golden
A1 Heini M. Miettinen
A1 Andrew Santiago-Frangos
A1 Dominick Faith
A1 C. Martin Lawrence
A1 Gabriel C. Lander
A1 Blake Wiedenheft
YR 2018
UL http://biorxiv.org/content/early/2018/10/26/453720.abstract
AB Bacteria and archaea have evolved sophisticated adaptive immune systems that rely on CRISPR RNA (crRNA)-guided detection and nuclease-mediated elimination of invading nucleic acids. Here we present the cryo-EM structure of the type I-F CRISPR RNA-guided surveillance complex (Csy complex) from Pseudomonas aeruginosa bound to a double-stranded DNA target. Comparison of this structure to previously determined structures of this complex reveals a Ȉ180-degree rotation of the C-terminal helical bundle on the “large” Cas8f subunit. We show that the dsDNA-induced conformational change in Cas8f exposes a Cas2/3 “nuclease recruitment helix” that is structurally homologous to a virally encoded anti-CRISPR protein (AcrIF3). Structural homology between Cas8f and AcrIF3 suggests that AcrIF3 is a mimic of the Cas8f “nuclease recruitment helix”, implying that cas genes may sometimes serve as genetic fodder for the evolution of anti-CRISPRs.