Structural biology. Structures of the CRISPR-Cmr complex reveal mode of RNA target positioning

David W Taylor; Yifan Zhu; Raymond H J Staals; Jack E Kornfeld; Akeo Shinkai; John van der Oost; Eva Nogales; Jennifer A Doudna

doi:10.1126/science.aaa4535

Structural biology. Structures of the CRISPR-Cmr complex reveal mode of RNA target positioning

Science. 2015 May 1;348(6234):581-5. doi: 10.1126/science.aaa4535. Epub 2015 Apr 2.

Authors

David W Taylor¹, Yifan Zhu², Raymond H J Staals², Jack E Kornfeld³, Akeo Shinkai⁴, John van der Oost², Eva Nogales⁵, Jennifer A Doudna⁶

Affiliations

¹ Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA. California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA.
² Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB Wageningen, Netherlands.
³ Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
⁴ RIKEN SPring-8 Center, Hyogo 679-5148, Japan. RIKEN Structural Biology Laboratory, Kanagawa 230-0045, Japan.
⁵ Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA. California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA. Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. doudna@berkeley.edu enogales@lbl.gov.
⁶ Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA. California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA. Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. Department of Chemistry, University of California, Berkeley, CA 94720, USA. Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. doudna@berkeley.edu enogales@lbl.gov.

Abstract

Adaptive immunity in bacteria involves RNA-guided surveillance complexes that use CRISPR (clustered regularly interspaced short palindromic repeats)-associated (Cas) proteins together with CRISPR RNAs (crRNAs) to target invasive nucleic acids for degradation. Whereas type I and type II CRISPR-Cas surveillance complexes target double-stranded DNA, type III complexes target single-stranded RNA. Near-atomic resolution cryo-electron microscopy reconstructions of native type III Cmr (CRISPR RAMP module) complexes in the absence and presence of target RNA reveal a helical protein arrangement that positions the crRNA for substrate binding. Thumblike β hairpins intercalate between segments of duplexed crRNA:target RNA to facilitate cleavage of the target at 6-nucleotide intervals. The Cmr complex is architecturally similar to the type I CRISPR-Cascade complex, suggesting divergent evolution of these immune systems from a common ancestor.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Clustered Regularly Interspaced Short Palindromic Repeats*
Cryoelectron Microscopy
Multiprotein Complexes / chemistry*
Multiprotein Complexes / ultrastructure
RNA / chemistry*
RNA / ultrastructure
RNA Cleavage*
Thermus thermophilus / immunology*

Substances

Multiprotein Complexes
RNA

Grants and funding

HHMI/Howard Hughes Medical Institute/United States