In the thermophilic archaeon Sulfolobus solfataricus a DNA-binding protein is in vitro (Adpribosyl)ated.

A small protein with high affinity for homologous DNA was isolated from Sulfolobus solfataricus homogenate by mineral acid extraction. It was purified using a two-step procedure including CM-cellulose and RP-HPL chromatographies. The protein was electrophoretically homogeneous, had a molecular weight of 7.147 kDa and an amino acid composition with a high content of lysine and glutamic acid residues. The protein was able to protect DNA against thermal denaturation and DNAse I digestion in a dose-dependent manner. After incubation of the sulfolobal homogenate in the presence of 32P-NAD, followed by the purification steps, the protein was modified by ADPribose, as revealed by reaction product analysis, SDS-PAGE and autoradiography.