Structural organization of a Type III-A CRISPR effector subcomplex determined by X-ray crystallography and cryo-EM

Bryan W. Dorsey, Lei Huang, Alfonso Mondragón*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated Cas proteins provide an immune-like response in many prokaryotes against extraneous nucleic acids. CRISPR-Cas systems are classified into different classes and types. Class 1 CRISPR-Cas systems form multi-protein effector complexes that includes a guide RNA (crRNA) used to identify the target for destruction. Here we present crystal structures of Staphylococcus epidermidis Type III-A CRISPR subunits Csm2 and Csm3 and a 5.2 Å resolution single-particle cryo-electron microscopy (cryo-EM) reconstruction of an in vivo assembled effector subcomplex including the crRNA. The structures help to clarify the quaternary architecture of Type III-A effector complexes, and provide details on crRNA binding, target RNA binding and cleavage, and intermolecular interactions essential for effector complex assembly. The structures allow a better understanding of the organization of Type III-A CRISPR effector complexes as well as highlighting the overall similarities and differences with other Class 1 effector complexes.

Original languageEnglish (US)
Pages (from-to)3765-3783
Number of pages19
JournalNucleic acids research
Volume47
Issue number7
DOIs
StatePublished - 2019

ASJC Scopus subject areas

  • Genetics

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