CRISPR (clustered regularly interspaced short palindromic repeat) is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain spacers, sequences complementary to antecedent mobile elements, and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA) (By similarity). Has a role in fruiting body development, sporulation and aggregation. Operon expression begins by 6 hours after starvation has initiated development and is under strong negative autoregulation. Part of an operon going from at least MXAN_7266 to MXAN_7259 that includes a CRISPR operon with transcription continuing into the pre-crRNA locus. Essential for sporulation, decreases sporulation 100 to 1000-fold. Negative autoregulation by this gene product relies on DNA both upstream and downstream of the operon's promoter. Belongs to the CRISPR-associated protein Cas5 family.