EXPRESSION IN ESCHERICHIA-COLI OF THE 36 KDA DOMAIN OF POLY(ADP-RIBOSE) POLYMERASE AND INVESTIGATION OF ITS DNA-BINDING PROPERTIES

We have expressed in Escherichia coli the 36 kDa domain of the human p oly(ADP-ribose) polymerase. This polypeptide comprises the C-terminal part of the DNA binding domain, as well as the auto-modification regio n of the enzyme, but lacks the zinc-finger motifs of the N-terminal re gion and the C-terminal catalytic domain. By probing the crude E. coli protein extracts with radioactive DNA probes (South-Western blots), w e have shown that the 36 kDa domain binds a DNA probe of 222 bp but do es not bind a shorter probe of 66 bp. This interaction is stronger whe n the polypeptide is fused to the 55 kDa catalytic domain of the enzym e.