An endonuclease fromCaenorhabditis elegans: Partial purification and characterization

A deoxyribonuclease was partially purified from the free-living nematodeCaenorhabditis elegans. The DNase functioned as an endonuclease and introduced both single-strand nicks and double-strand breaks into DNA. The enzyme hydrolyzed double-stranded DNA seven times more rapidly than single-stranded DNA. DNase activity was not affected by the addition of divalent cations below 1mm but was inhibited at higher ionic concentrations. In addition, the enzyme was not inhibited in the presence of 10mm EDTA. The enzyme was inhibited by salt concentrations greater than 20mm. Three independent mutations in thenuc-1 gene were shown to reduce nuclease activity to less than 1% of that seen in wild-type organisms. This work was supported by National Institutes of Health Grant AG03161 and a TCU Research Foundation Grant. Some stocks used in these experiments were obtained from theCaenorhabditis Genetics Center, which is supported by Contract NOI-AG-9-2113 between the NIH and the curators of the University of Missouri.