Poly (ADP-ribose) polymerase auto-modification and interaction with DNA: electron microscopic visualization
de Murcia, G.; Jongstra-Bilen, J.; Ittel, M.E.; Mandel, P.; Delain, E.
EMBO Journal 2(4): 543-548
1983
ISSN/ISBN: 0261-4189 PMID: 6313345 Document Number: 199573
The interaction between purified calf thymus poly(ADP-ribose) polymerase and its activating co-purified DNA (sDNA) was investigated by electron microscopy. We have shown that the enzyme-DNA complex possesses a nucleosome-like structure. The enzyme-bound DNA (sDNA) was found to be enriched in single-stranded regions and branched structures, presumed to be replication forks. The auto-ribosylated polymerase as well as the branched poly(ADP-ribose) formed were visualized by dark field electron microscopy during the auto-ADP-ribosylation reaction and the possible mechanism of this phenomenon is discussed.