title: A shuttle mechanism for DNA-protein interactions. The regulation of poly(ADP-ribose) polymerase.
abstract: Previously it had been shown that poly(ADP-ribose) polymerase requires DNA for its activity and that this enzyme is auto-poly(ADP-ribosyl)ated. The studies reported here indicate that this self-modification inhibits the enzyme and decreases its affinity for DNA, as shown by sucrose gradient density centrifugation. The coupling of poly(ADP-ribose) polymerase with poly(ADP-ribose) glycohydrolase reactivates the polymerase by degrading poly(ADP-ribose) and restoring the polymerase-DNA complex. The assay of polymerase in the presence of glyco-hydrolase was made possible by use of a double-label assay involving release of 14C-labelled nicotinamide and the incorporation of 3H-labelled ADP-ribose from NAD+. These results provide the basis for a shuttle mechanism in which the polymerase can be moved on and off DNA by the action of these two enzymes. Mg2+ and histone H1 appear to activate the polymerase by increasing the affinity of the polymerase for DNA.
mesh_terms: D000818:Animals; D002417:Cattle; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000378:metabolism; D006657:Histones / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009244:NAD+ Nucleosidase / Q000378:metabolism*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011485:Protein Binding; D013950:Thymus Gland / Q000201:enzymology
chemical_list: D006657:Histones; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D004247:DNA; D011065:Poly(ADP-ribose) Polymerases; D006026:Glycoside Hydrolases; C022407:poly ADP-ribose glycohydrolase; D009244:NAD+ Nucleosidase; D008274:Magnesium