CDNA CLONING OF HUMAN DNASE-GAMMA - CHROMOSOMAL LOCALIZATION OF ITS GENE AND ENZYMATIC-PROPERTIES OF RECOMBINANT PROTEIN

We report here on the nucleotide sequence of the cDNA encoding human D Nase gamma, which is a candidate for an apoptotic endonuclease. The cD NA clone isolated from a human spleen cDNA library is composed of a 91 8 bp open reading frame encoding a 305 amino acid precursor protein fo r DNase gamma, Northern blot analysis reveals that the expression of a single transcript of 1.5 kb DNase gamma mRNA is detected in the splee n and liver. The chromosomal localization of DNase gamma gene is mappe d to chromosome 3 at region p21.1-p14.2 by fluorescence in situ hybrid ization (FISH). Characterization of thioredoxin-DNase gamma fusion pro tein (Trx-hDNase gamma) shows that the recombinant protein has a Ca2+/ Mg2+- or Mn2+-dependent endonuclease activity that cleaves chromatin D NA to nucleosomal units. The optimum pH is around 7.2. Zn2+ and aurint ricarboxylic acid (ATA) inhibits the activity in dose-dependent manner s. These properties are identical to those of purified DNase gamma.