ADPribosylation reaction by free ADPribose in Sulfolobus solfataricus,a thermophilic archaeon

In the archaeon Sulfolobus solfataricus, protein ADPribosylation by free ADPribose was demonstrated by testing both adenine-¹⁴C(U)]ADPR and adenine- ¹⁴C(U)]NAD as substrates. The occurrence of this process was shown by using specific experimental conditions. Increasing the incubation time and lowering the pH of the reaction mixture enhanced the protein glycation by free ADPribose. At pH 7.5 and 10 min incubation, the incorporation of free ADPribose into proteins was highly reduced. Under these conditions, the autoradiographic pattern showed that, among the targets of ADPribose electrophoresed after incubation with ³²P-NAD, the proteins modified by free ³²P-ADPribose mostly corresponded to high molecular mass components. Among the compounds known to inhibit the eukaryotic poly-ADPribose polymerase, only ZnCl₂ highly reduced the ADPribose incorporation from NAD into the ammonium sulphate precipitate. A 20% inhibition was measured in the presence of nicotinamide or 3-aminobenzamide. No inhibition was observed replacing NAD with ADPR as substrate. J. Cell. Biochem. 66: 37–42, 1997. © 1997 Wiley-Liss, Inc.