Nus factors prevent premature transcription termination of bacterial CRISPR arrays

We used ChIP-seq to map binding of the CRISPR surveillance complex, Cascade, in a Salmonella enterica serovar Typhimurium strain lacking the gene encoding the endonuclease Cas3. We performed ChIP-seq in strains with wild-type and mutant sequences upstream of the two CRISPR arrays, and in strains with wild-type and mutant nusE genes to determine the impact of Nus factor antitermination on CRISPR array function.