Regulation of Poly(ADP-ribose) Polymerase-1 by DNA Structure-specific Binding

作者：Irina Lonskaya, Vladimir N. Potaman, Luda S. Shlyakhtenko, Elena A. Oussatcheva, Yuri L. Lyubchenko, Viatcheslav A. Soldatenkov · 发表于：Journal of Biological Chemistry · 年份：2005 · DOI：10.1074/jbc.m413483200 · 被引用次数：186 · 研究领域：PARP inhibition in cancer therapy、Toxin Mechanisms and Immunotoxins、DNA Repair Mechanisms

Poly(ADP-ribose) polymerase-1 (PARP-1) is an intracellular sensor of DNA strand breaks and plays a critical role in cellular responses to DNA damage. In normally functioning cells, PARP-1 enzymatic activity has been linked to the alterations in chromatin structure associated with gene expression. However, the molecular determinants for PARP-1 recruitment to specific sites in chromatin in the absence of DNA strand breaks remain obscure. Using gel shift and enzymatic footprinting assays and atomic force microscopy, we show that PARP-1 recognizes distortions in the DNA helical backbone and that it binds to three- and four-way junctions as well as to stably unpaired regions in double-stranded DNA. PARP-1 interactions with non-B DNA structures are functional and lead to its catalytic activation. DNA hairpins, cruciforms, and stably unpaired regions are all effective co-activators of PARP-1 auto-modification and poly(ADP-ribosyl)ation of histone H1 in the absence of free DNA ends. Enzyme kinetic analyses revealed that the structural features of non-B form DNA co-factors are important for PARP-1 catalysis activated by undamaged DNA. K 0.5 constants for DNA co-factors, which are structurally different in the degree of base pairing and spatial DNA organization, follow the order: cruciform ≤ hairpin « loop. DNA structure also influenced the reaction rate; when a hairpin was substituted with a stably unpaired region, the maximum reaction velocity decreased almost 2-fold. These data sugg...