Deoxyribonuclease I (usually called DNase I), is an endonuclease coded by the human gene DNASE1.[5]
DNase I is a nuclease that cleaves DNA preferentially at phosphodiester linkages adjacent to a pyrimidinenucleotide, yielding 5'-phosphate-terminated polynucleotides with a free hydroxyl group on position 3', on average producing tetranucleotides. It acts on single-stranded DNA, double-stranded DNA, and chromatin. In addition to its role as a waste-management endonuclease, it has been suggested to be one of the deoxyribonucleases responsible for DNA fragmentation during apoptosis.[6]
DNase I binds to the cytoskeletal protein actin. It binds actin monomers with very high (sub-nanomolar) affinity and actin polymers with lower affinity. The function of this interaction is unclear. However, since actin-bound DNase I is enzymatically inactive, the DNase-actin complex might be a storage form of DNase I that prevents damage of the genetic information.
In genomics, DNase I hypersensitive sites are thought to be characterized by open, accessible chromatin; therefore, a DNase I sensitivity assay is a widely used methodology in genomics for identifying which regions of the genome are likely to contain active genes [7]
DNase I Sequence Specificity
It has been recently reported that DNase I shows some levels of sequence specificity that may depend on experimental conditions.[8] In contrast to other enzymes which have high substrate specificity, DNase I certainly does not cleave with an absolute sequence specificity. However, cleavage at sites that contain C or G at their 3' end is less efficient.
^Koohy, Hashem; Down, Thomas A.; Hubbard, Tim J.; Mariño-Ramírez, Leonardo (26 July 2013). "Chromatin Accessibility Data Sets Show Bias Due to Sequence Specificity of the DNase I Enzyme". PLoS ONE. 8 (7): e69853. doi:10.1371/journal.pone.0069853.{{cite journal}}: CS1 maint: unflagged free DOI (link)
