DNaseIc

deoxyribonuclease I
DNaseIc
SMART accession number:SM00476
Description: Deoxyribonuclease I catalyzes the endonucleolytic cleavage of double-stranded DNA. The enzyme is secreted outside the cell and also involved in apoptosis in the nucleus.
Interpro abstract (IPR016202):

Deoxyribonuclease I (DNase I) (EC 3.1.21.1) [(PUBMED:3713845)] is a vertebrate enzyme which catalyzes the endonucleolytic cleavage of double-stranded DNA to 5'- phosphodinucleotide and 5'-phosphooligonucleotide end-products. DNase I is an enzyme involved in DNA degradation; it is normally secreted outside of the cell but seems to be able to gain access to the nucleus where it is involved in cell death by apoptosis [(PUBMED:8428592)].

As shown in the following schematic representation, DNase I is a glycoprotein of about 260 residues with two conserved disulphide bonds.


+-+ +--------+
| | | |
xxxxxxxxxxxxxxxxx#xxxxxxCxCxxxxx#xxxxxxxxxCxxxxxxxxCxxxxxxxxxxxxx
'C': conserved cysteine involved in a disulphide bond.
'#': active site residue.

DNase I has a pH-optimum around 7.5 and requires calcium and magnesium for full activity. It causes single strand nicks in duplex DNA. A proton acceptor-donor chain composed of an histidine and a glutamic acid produce a nucleophilic hydroxyl ion from water, which cleaves the 3'-P-O bond [(PUBMED:3352748)].

DNase I forms a 1:1 complex with G-actin, resulting in the inhibition of DNase activity and loss of the ability of G-actin to polymerise into fibres [(PUBMED:2395459)].

DNase I has been used in the treatment of lung problems in patients with cystic fibrosis: here it acts by degrading DNA found in purulent lung secretions, reducing their viscosity and making it easier for the patient to breathe [(PUBMED:2251263)].

The sequence of DNase I is evolutionary related to that of human muscle-specific DNase-like protein and human proteins DHP1 and DHP2. However, the first disulphide bond of DNase I is not conserved in these proteins.

This entry represents DNaseI and related proteins such as DNase gamma.

GO process:DNA catabolic process (GO:0006308)
GO function:deoxyribonuclease activity (GO:0004536)
Family alignment:
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There are 721 DNaseIc domains in 714 proteins in SMART's nrdb database.

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