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 DNase gamma, which is a candidate for an apoptotic endonuclease. The cDNA clone isolated from a human spleen cDNA library is composed of a 918 bp open reading frame encoding a 305 amino acid precursor protein for DNase gamma. Northern blot analysis reveals that the expression of a single transcript of 1.5 kb DNase gamma mRNA is detected in the spleen and liver. The chromosomal localization of DNase gamma gene is mapped to chromosome 3 at region p21.1-p14.2 by fluorescence in situ hybridization (FISH). Characterization of thioredoxin-DNase gamma fusion protein (Trx-hDNase gamma) shows that the recombinant protein has a Ca(2+)/Mg(2+)- or Mn(2+)-dependent endonuclease activity that cleaves chromatin DNA to nucleosomal units. The optimum pH is around 7.2. Zn(2+) and aurintricarboxylic acid (ATA) inhibits the activity in dose-dependent manners. These properties are identical to those of purified DNase gamma.
Shiokawa
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D
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Shinjuku-ku, Tokyo, Japan.
Hirai
M
M
Tanuma
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S