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bioRxiv · 10.1101/2025.01.06.631587

Single-molecule analysis of PARP1-G-quadruplex interaction

Gaur, P.·Bain, F. E.·Meah, R.·Spies, M.
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Abstract

The human genome contains numerous repetitive nucleotide sequences that display a propensity to fold into non-canonical DNA structures including G-quadruplexes (G4s). G4s have both positive and negative impacts on various aspects of nucleic acid metabolism including DNA replication, DNA repair and RNA transcription. Poly (ADP-ribose) polymerase (PARP1), an important anticancer drug target, has been recently shown to bind a subset of G4s, and to undergo auto-PARylation. The mechanism of this interaction, however, is poorly understood. Utilizing Mass Photometry (MP) and single-molecule total internal reflection fluorescence microscopy (smTIRFM), we demonstrate that PARP1 dynamically interacts with G4s with a 1:1 stoichiometry. Interaction of a single PARP1 molecule with nicked DNA or DNA containing G4 and a primer-template junction is sufficient to activate robust auto-PARylation resulting in the addition of poly (ADP-ribose) chains with molecular weight of several hundred kDa. Pharmacological PARP inhibitors EB-47, Olaparib and Veliparib differently affect PARP1 retention on G4-containing DNA compared to nicked DNA.

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Gaur, P., Bain, F. E., Meah, R., Spies, M.. 2025-01-08. Single-molecule analysis of PARP1-G-quadruplex interaction. https://doi.org/10.1101/2025.01.06.631587

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