Prespacer processing and specific integration in a Type I-A CRISPR system
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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.
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 . DOI: 10.1093/nar/gkx1232
Nucleic Acids Research
© The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org / licenses / by / 4.0 / ), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
DescriptionThis work was supported by a grant from the Biotechnology and Biological Sciences Research Council (REF: BB/M021017/1 to MFW).
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