Primary structure of human poly(ADP-ribose) synthetase as deduced from cDNA sequence.

Human poly(ADP-ribose) synthetase consists of three proteolytically separable domains, the first for binding of DNA, the second for automodification, and the third for binding of the substrate, NAD (Ushiro, H., Yokoyama, Y., and Shizuta, Y. (1987) J. Biol. Chem. 262, 2352-2357). We have isolated and sequenced cDNA clones for the enzyme using synthesized oligodeoxyribonucleotide probes based on the partial amino acid sequence of the protein. The open reading frame determined encodes a protein of 1,013 amino acid residues with a molecular weight of 113,203. The deduced amino acid sequence is consistent with the partial amino acid sequences of tryptic or alpha-chymotryptic peptides and the total amino acid composition of the purified enzyme. The native enzyme is relatively hydrophilic as judged from the hydrophilicity profile of the total amino acid sequence. The net charge of the NAD binding domain is neutral but the DNA binding domain and the automodification domain are considerably rich in lysine residue and quite basic. The DNA binding domain involves a homologous repeat in the sequence and exhibits a sequence homology with localized regions of transforming proteins such as c-fos and v-fos. Furthermore, this domain contains a unique sequence element which resembles the essential peptide sequences for nuclear location of SV40 and polyoma virus large T antigens. These facts suggest the possibility that the physiological function of poly(ADP-ribose) synthetase lies in its ability to bind to DNA and to control transformation of living eukaryotic cells like the cases of those oncogene products.