Prespacer processing and specific integration in a Type I-A CRISPR system
Abstract
The CRISPR–Cas system for prokaryotic adaptive immunity provides RNA-mediated protection from viruses and mobile genetic elements. Adaptation is dependent on the Cas1 and Cas2 proteins along with varying accessory proteins. Here we analyse the process in Sulfolobus solfataricus, showing that while Cas1 and Cas2 catalyze spacer integration in vitro, host factors are required for specificity. Specific integration also requires at least 400 bp of the leader sequence, and is dependent on the presence of hydrolysable ATP, suggestive of an active process that may involve DNA remodelling. Specific spacer integration is associated with processing of prespacer 3′ ends in a PAM-dependent manner. This is reflected in PAM-dependent processing of prespacer 3′ ends in vitro in the presence of cell lysate or the Cas4 nuclease, in a reaction consistent with PAM-directed binding and protection of prespacer DNA. These results highlight the diverse interplay between CRISPR–Cas elements and host proteins across CRISPR types.
Citation
Rollie , C , Graham , S , Rouillon , C & White , M F 2018 , ' Prespacer processing and specific integration in a Type I-A CRISPR system ' , Nucleic Acids Research , vol. 46 , no. 3 , pp. 1007-1020 . https://doi.org/10.1093/nar/gkx1232
Publication
Nucleic Acids Research
Status
Peer reviewed
ISSN
0305-1048Type
Journal article
Description
This work was supported by a grant from the Biotechnology and Biological Sciences Research Council (REF: BB/M021017/1 to MFW).Collections
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