Cas9 senses CRISPR RNA abundance to regulate CRISPR spacer acquisition.

ABSTRACT: Prokaryotes create adaptive immune memories by acquiring foreign DNA snippets, known as spacers, into the CRISPR array¹. In type II CRISPR-Cas systems, the RNA-guided effector Cas9 also assists the acquisition machinery by selecting spacers from the protospacer adjacent motif-flanked DNA^2,3. Here we uncovered the first biological role of Cas9 that is independent of its dual RNA partners. Following depletion of CRISPR RNA (crRNA) and/or trans-activating CRISPR RNA, Neisseria apoCas9 stimulates spacer acquisition efficiency. Physiologically, Cas9 senses low concentrations of crRNA in cells with short CRISPR arrays, such as those undergoing array neogenesis or natural array contractions, and dynamically upregulates acquisition to quickly expand the small immune memory ba

SUBMITTER: Zhou X 

PROVIDER: S-EPMC12477760 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature