DSSR-PyMOL cartoon-block schematics: PDB entry 6ne0

PDB-id

6ne0; DSSR-derived features in text and JSON formats

Class

immune system-RNA

Method

cryo-EM (3.4 Å)

Summary

Structure of double-stranded target DNA engaged csy complex from pseudomonas aeruginosa (pa-14)

Reference

Rollins MF, Chowdhury S, Carter J, Golden SM, Miettinen HM, Santiago-Frangos A, Faith D, Lawrence CM, Lander GC, Wiedenheft B (2019): "Structure Reveals a Mechanism of CRISPR-RNA-Guided Nuclease Recruitment and Anti-CRISPR Viral Mimicry." Mol. Cell, 74, 132-142.e5. doi: 10.1016/j.molcel.2019.02.001.

Abstract

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-electron microscopy (cryo-EM) structure of the type I-F crRNA-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 ∼180-degree rotation of the C-terminal helical bundle on the "large" Cas8f subunit. We show that the double-stranded DNA (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.