A third zinc-binding domain of human poly(ADP-ribose) polymerase-1 coordinates DNA-dependent enzyme activation.
Poly(ADP-ribose) polymerase-1 (PARP-1) is a chromatin-associated enzyme with multiple cellular functions, including DNA repair, transcriptional regulation, and cell signaling. PARP-1 has a modular architecture with six independent domains comprising the 113-kDa polypeptide. Two zinc finger domains at the N terminus of PARP-1 bind to DNA and thereby activate the catalytic domain situated at the C terminus of the enzyme. The tight coupling of DNA binding and catalytic activities is critical to the cellular regulation of PARP-1 function; however, the mechanism for coordinating these activities remains an unsolved problem. Here, we demonstrate using spectroscopic and crystallographic analysis that human PARP-1 has a third zinc-binding domain. Biochemical mutagenesis and deletion analysis indicate that this region mediates interdomain contacts important for DNA-dependent enzyme activation. The crystal structure of the third zinc-binding domain reveals a zinc ribbon fold and suggests conserved residues that could form interdomain contacts. The new zinc-binding domain self-associates in the crystal lattice to form a homodimer with a head-totail arrangement. The structure of the homodimer provides a scaffold for assembling the activated state of PARP-1 and suggests a mechanism for coupling the DNA binding and catalytic functions of PARP-1.
Department of Biochemistry and Molecular Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Marie-France
MF
Langelier
Kristin M
KM
Servent
Elizabeth E
EE
Rogers
John M
JM
Pascal
D000595:Amino Acid Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004789:Enzyme Activation; D005454:Fluorescence Polarization; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013054:Spectrophotometry, Atomic; D015032:Zinc / Q000378:metabolism*
C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D015032:Zinc