7KHA

Cryo-EM Structure of the Desulfovibrio vulgaris Type I-C Apo Cascade

Summary for 7KHA

• Entry DOI: 10.2210/pdb7kha/pdb
• EMDB information: 22876
• Descriptor: CRISPR-associated protein, CT1134 family, CRISPR-associated protein, TM1801 family, CRISPR-associated protein, CT1133 family, ... (5 entities in total)
• Functional Keywords: crispr, cascade, rna binding protein-rna complex, rna binding protein/rna
• Biological source: Desulfovibrio vulgaris (strain Hildenborough / ATCC 29579 / DSM 644 / NCIMB 8303); More
• Total number of polymer chains: 12
• Total formula weight: 353567.83

Authors

O'Brien, R.,Wrapp, D.,Bravo, J.P.K.,Schwartz, E.,Taylor, D. (deposition date: 2020-10-20, release date: 2020-11-11, Last modification date: 2024-03-06)

Primary citation

O'Brien, R.E.,Santos, I.C.,Wrapp, D.,Bravo, J.P.K.,Schwartz, E.A.,Brodbelt, J.S.,Taylor, D.W.
Structural basis for assembly of non-canonical small subunits into type I-C Cascade.
Nat Commun, 11:5931-5931, 2020

PubMed Abstract: Bacteria and archaea employ CRISPR (clustered, regularly, interspaced, short palindromic repeats)-Cas (CRISPR-associated) systems as a type of adaptive immunity to target and degrade foreign nucleic acids. While a myriad of CRISPR-Cas systems have been identified to date, type I-C is one of the most commonly found subtypes in nature. Interestingly, the type I-C system employs a minimal Cascade effector complex, which encodes only three unique subunits in its operon. Here, we present a 3.1 Å resolution cryo-EM structure of the Desulfovibrio vulgaris type I-C Cascade, revealing the molecular mechanisms that underlie RNA-directed complex assembly. We demonstrate how this minimal Cascade utilizes previously overlooked, non-canonical small subunits to stabilize R-loop formation. Furthermore, we describe putative PAM and Cas3 binding sites. These findings provide the structural basis for harnessing the type I-C Cascade as a genome-engineering tool.

PubMed: 33230133
DOI: 10.1038/s41467-020-19785-8

Experimental method

ELECTRON MICROSCOPY (3.13 Å)