CRISPR arrays are transcribed into long precursor RNA species， which are further processed into mature CRISPR RNAs (crRNAs). Cas proteins utilize these crRNAs， which contain spacer sequences that can be derived from mobile genetic elements， to mediate immunity during a reoccurring virus infection. Type I CRISPR-Cas systems are defined by the presence of different Cascade interference complexes containing large and small subunits that play major roles during target DNA selection.
CRISPR arrays are transcribed into long precursor RNA species， which are further processed into mature CRISPR RNAs (crRNAs). Cas proteins utilize these crRNAs， which contain spacer sequences that can be derived from mobile genetic elements， to mediate immunity during a reoccurring virus infection. Type I CRISPR-Cas systems are defined by the presence of different Cascade interference complexes containing large and small subunits that play major roles during target DNA selection.
