2. Academic Validation
  3. A PARP2 active site helix melts to permit DNA damage-induced enzymatic activation

A PARP2 active site helix melts to permit DNA damage-induced enzymatic activation

  • Mol Cell. 2025 Mar 6;85(5):865-876.e4. doi: 10.1016/j.molcel.2025.01.004.
Emily S Smith-Pillet 1,  Ramya Billur 2,  Marie-France Langelier 3,  Tanaji T Talele 4,  John M Pascal 3,  Ben E Black 5
Affiliations

Affiliations

  • 1 Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19140-6059, USA; Graduate Program in Biochemistry, Biophysics, Chemical Biology, University of Pennsylvania, Philadelphia, PA 19140-6059, USA.
  • 2 Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19140-6059, USA.
  • 3 Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada.
  • 4 Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY 11439, USA.
  • 5 Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19140-6059, USA; Graduate Program in Biochemistry, Biophysics, Chemical Biology, University of Pennsylvania, Philadelphia, PA 19140-6059, USA. Electronic address: blackbe@pennmedicine.upenn.edu.
PMID: 39889708 DOI: 10.1016/j.molcel.2025.01.004
Abstract

Poly(ADP-ribose) polymerase 1 (PARP1) and PARP2 recognize DNA breaks immediately upon their formation, generate a burst of local PARylation to signal their location, and are co-targeted by all current FDA-approved forms of PARP inhibitors (PARPi) used in the Cancer clinic. Recent evidence indicates that the same PARPi molecules impact PARP2 differently from PARP1, raising the possibility that allosteric activation may also differ. We find that, unlike for PARP1, destabilization of the autoinhibitory domain of PARP2 is insufficient for DNA damage-induced catalytic activation. Rather, PARP2 activation requires further unfolding of an active site helix. In contrast, the corresponding helix in PARP1 only transiently forms, even prior to engaging DNA. Only one clinical PARPi, Olaparib, stabilizes the PARP2 active site helix, representing a structural feature with the potential to discriminate small molecule inhibitors. Collectively, our findings reveal unanticipated differences in local structure and changes in activation-coupled backbone dynamics between human PARP1 and PARP2.

Keywords

DNA damage; DNA damage detection; PARP enzymes; PARP1; PARP2; PARPi; PARylation; deuterium exchange; mass spectrometry.

Figures
Products
  • Cat. No.
    Product Name
    Description
    Target
    Research Area
  • HY-132167
    99.76%, PARP Inhibitor