DNA Motifs and an Accessory CRISPR Factor Determine Cas1 Binding and Integration Activity in Sulfolobus islandicus.

ABSTRACT: CRISPR-Cas systems empower prokaryotes with adaptive immunity against invasive mobile genetic elements. At the first step of CRISPR immunity adaptation, short DNA fragments from the invaders are integrated into CRISPR arrays at the leader-proximal end. To date, the mechanism of recognition of the leader-proximal end remains largely unknown. Here, in the Sulfolobus islandicus subtype I-A system, we show that mutations destroying the proximal region reduce CRISPR adaptation in vivo. We identify that a stem-loop structure is present on the leader-proximal end, and we demonstrate that Cas1 preferentially binds the stem-loop structure in vitro. Moreover, we demonstrate that the integrase activity of Cas1 is modulated by interacting with a CRISPR-associated factor Csa3a. When translocated

SUBMITTER: Liu T 

PROVIDER: S-EPMC9456107 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature