Sequencing of fragments assosiated with Cas1 and Cas3 during priming in I-E system of E. coli

We performed chromatin immunoprecipitation with Cas3-specific and Cas1-specific antibodies using cells undergoing primed adaptation. We found that the same prespacers are bound by Cas1 (presumably, as part of the Cas1-Cas2 integrase), and Cas3 implying physical association of the interference nuclease-helicase with the adaptation machinery as part of primed adaptation complex