Inhibition of homodimerization of poly(ADP-ribose) polymerase by its C-terminal cleavage products produced during apoptosis.
The biochemical role of the C-terminal fragment of poly(ADP-ribose) polymerase (PARP) was investigated in HeLa cells undergoing UV-mediated apoptosis. During the course of apoptosis, the C-terminal cleavage product of PARP interacted with intact PARP and down-regulated PARP activity by blocking the homodimerization of PARP. The basic leucine zipper motif in the auto-modification domain of the C-terminal fragment of PARP represented the site of association, and Leu(405) was critical to the ability of the basic leucine zipper motif to associate with intact PARP. The expression of the C-terminal fragment of PARP stimulated UV-mediated apoptosis. These results suggest that the C-terminal cleavage product of PARP produced during apoptosis blocks the homodimerization of PARP and inhibits the cellular PARP activity. The inhibition of the cellular PARP activity might prevent cellular NAD(+) depletion and stimulate apoptosis by maintaining the basal cellular energy level required for the completion of apoptosis.
Kim
J W
JW
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, 305-701, South Korea.
Kim
K
K
Kang
K
K
Joe
C O
CO
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D019281:Dimerization; D006367:HeLa Cells / Q000528:radiation effects; D006801:Humans; D016350:Leucine Zippers; D010446:Peptide Fragments / Q000494:pharmacology*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D014466:Ultraviolet Rays
D010446:Peptide Fragments; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D000246:Adenosine Diphosphate Ribose