DNA‐dependent mono(ADP‐ribosyl)ation of p33, an acceptor protein in hen liver nuclei

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Abstract
A non‐histone acceptor protein for hen liver nuclear ADP‐ribosyltransferase was purified to an apparently homogeneous state through salt extraction and chromatography on hydroxyapatite, phenyl‐Sepharose, carboxymethyl‐cellulose, Sephadex G‐75, phenyl 5‐PW, mono S and Radial PAK C18. This protein was termed p33. The ADP‐ribosylation of p33 was enhanced more than 60‐fold by double‐stranded DNA. Single‐stranded DNA, RNA and poly(L‐glutamate), but not deoxyribonucleotide, were partially effective. DNA‐dependent ADP‐ribosylation was also observed when whole histones were used as acceptor. DNA required for the maximal ADP‐ribosylation depended on the dose of the acceptor protein; the optimal mass ratio of DNA to the acceptor protein was 1:1 with both p33 and whole histones. DNA decreased the Km for NAD and concomitantly increased the Vmax value, but did not alter the Km for p33. These results are consistent with the idea that p33 may participate in chromatin processes such as replication or transcription, through modification by nuclear ADP‐ribosyltransferase.