Poly(ADP-ribose) polymerase auto-modification and interaction with DNA: electron microscopic visualization.

Abstract

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.

Radiosensitization by the poly(ADP-ribose) polymerase inhibitor 4-amino-1,8-naphthalimide is specific of the S phase of the cell cycle and involves arrest of DNA synthesis

“…These observations are fully consistent with the known role of PARP-1 in the assembly of the DNA synthesome and control of the replication forks (5,6,56,57). In agreement with these observations, we tentatively propose that the lethal effect of ANI in cells irradiated during the S phase results from the collision of unrepaired SSB with uncontrolled replication forks.…”

The Xenopus laevis mitochondrial protein mtDBP-C cooperatively folds the DNA in vitro.

“…These results suggest that the effect is essentially at the level of the writhing number. However, using the same electron microscopy technique, we did not find any beaded structures similar to those observed when histones (Moyne et al, 1981;Goulet et al, 1988) or other DNA-binding proteins (de Murcia et al, 1983) bind to DNA. In the case mtDBP-C, no visible accumulation of protein could be detected before the DNA collapses.…”

Mechanism of early biphasic activation of poly(ADP-ribose) polymerase-1 in response to ultraviolet B radiation

“…4A, top panel). In contrast, a basal level of PARP binding to control oligo, probably due to weak interaction with free DNA termini (Sastry et al, 1989) or inner regions of DNA (de Murcia et al, 1983), did not increase with increasing amounts of PARP. Earlier EMSA studies also reported a weak interaction between blunt ended duplex oligo and PARP-like zinc fingers (Petrucco, 2003) or PARP (Mendoza-Alvarez and Alvarez-Gonzalez, 2001); the latter study also showed that increasing the amount of PARP from 7 to 70 ng did not increase the extent of this non-specific retention of oligo by PARP.…”