CRISPR-Cas system is a prokaryotic adaptive immunity system that consists of cas genes, which participate in all phases of defense, and the CRISPR locus with series of repeats interspaced by spacers originating from foreign DNA. During the adaptation phase, a spacer is integrated into the CRISPR locus. The objective of this study is naive adaptation, occurring during the cell's initial contact with foreign DNA. The primary role in naive adaptation is mediated by the Cas1 and Cas2 proteins, which form an integration complex. However, in order for foreign DNA to become an integration complex's substrate, it is subjected to the helicase and exonuclease activities of the RecBCD enzyme. Recently, it has been discovered that the exonuclease activity of the RecBCD enzyme is not essential for this process. Here, for the first time, the role of DnaQ and ExoT exonucleases in naive adaptation was studied in vivo in E. coli. For that purpose, ΔdnaQ and ΔexoT mutants were constructed using recombineering and transformed with a plasmid carrying the cas1-cas2 genes. Spacer acquisition was analyzed using the PCR method. The obtained results indicate that DnaQ partially participates in processing, and that ExoT likely doesn't participate and can be replaced by other nucleases.. Similarly, for the first time in the context of adaptation, the role of the UvrD helicase was studied using ΔuvrD mutant. The results suggest that UvrD promotes naive adaptation, possibly by removing the RecA protein from single-stranded substrates.