, Volume 3, Issue 2, pp 89-95

cDNA Cloning of Human DNase γ: Chromosomal Localization of Its Gene and Enzymatic Properties of Recombinant Protein

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Abstract

We report here on the nucleotide sequence of the cDNA encoding human DNase γ, 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 γ. Northern blot analysis reveals that the expression of a single transcript of 1.5 kb DNase γ mRNA is detected in the spleen and liver. The chromosomal localization of DNase γ gene is mapped to chromosome 3 at region p21.1-p14.2 by fluorescence in situ hybridization (FISH). Characterization of thioredoxin-DNase γ fusion protein (Trx-hDNase γ) shows that the recombinant protein has a Ca2+/Mg2+- or Mn2+-dependent endonuclease activity that cleaves chromatin DNA to nucleosomal units. The optimum pH is around 7.2. Zn2+ and aurintricarboxylic acid (ATA) inhibits the activity in dose-dependent manners. These properties are identical to those of purified DNase γ.