The DNA binding and catalytic domains of poly(ADP-ribose) polymerase 1 cooperate in the regulation of chromatin structure and transcription.
We explored the mechanisms of chromatin compaction and transcriptional regulation by poly(ADP-ribose) polymerase 1 (PARP-1), a nucleosome-binding protein with an NAD(+)-dependent enzymatic activity. By using atomic force microscopy and a complementary set of biochemical assays with reconstituted chromatin, we showed that PARP-1 promotes the localized compaction of chromatin into supranucleosomal structures in a manner independent of the amino-terminal tails of core histones. In addition, we defined the domains of PARP-1 required for nucleosome binding, chromatin compaction, and transcriptional repression. Our results indicate that the DNA binding domain (DBD) of PARP-1 is necessary and sufficient for binding to nucleosomes, yet the DBD alone is unable to promote chromatin compaction and only partially represses RNA polymerase II-dependent transcription in an in vitro assay with chromatin templates (approximately 50% of the repression observed with wild-type PARP-1). Furthermore, our results show that the catalytic domain of PARP-1, which does not bind nucleosomes on its own, cooperates with the DBD to promote chromatin compaction and efficient transcriptional repression in a manner independent of its enzymatic activity. Collectively, our results have revealed a novel function for the catalytic domain in chromatin compaction. In addition, they show that the DBD and catalytic domain cooperate to regulate chromatin structure and chromatin-dependent transcription, providing mechanistic insights into how these domains contribute to the chromatin-dependent functions of PARP-1.
Wacker
David A
DA
Department of Molecular Biology and Genetics, Cornell University, 465 Biotechnology Building, Ithaca, NY 14853, USA.
Ruhl
Donald D
DD
Balagamwala
Ehsan H
EH
Hope
Kristine M
KM
Zhang
Tong
T
Kraus
W Lee
WL
D000818:Animals; D020134:Catalytic Domain; D002417:Cattle; D002843:Chromatin / Q000737:chemistry* / Q000235:genetics* / Q000648:ultrastructure; D004247:DNA / Q000378:metabolism*; D004330:Drosophila; D006657:Histones / Q000378:metabolism; D006801:Humans; D018625:Microscopy, Atomic Force; D050505:Mutant Proteins / Q000302:isolation & purification / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic