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 poly(ADP-ribose) polymerase. This polypeptide comprises the C-terminal part of the DNA binding domain, as well as the automodification region of the enzyme, but lacks the zinc-finger motifs of the N-terminal region and the C-terminal catalytic domain. By probing the crude E. coli protein extracts with radioactive DNA probes (South-Western blots), we have shown that the 36 kDa domain binds a DNA probe of 222 bp but does not bind a shorter probe of 66 bp. This interaction is stronger when the polypeptide is fused to the 55 kDa catalytic domain of the enzyme.