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PARP1 recruits SPRTN to DNA-protein crosslinks through a conserved poly-ADP-ribose binding domain

Katelyn Hurley, Liam P Leary, Martin Garcia

Biorxiv : the Preprint Server for Biology

|January 16, 2026

Abstract:

DNA-protein crosslinks (DPCs) are toxic DNA lesions formed by the covalent attachment of proteins to DNA. Failure to resolve DPCs leads to genomic instability, premature aging, and cancer predisposition. Although multiple proteases and the 26S proteasome degrade DPCs, how these lesions are detected and marked for proteolysis remains unclear. Here, we show that poly-(ADP-ribose) polymerases (PARP1/2) sense DPCs and modify them with poly(ADP-ribose) (PAR) to promote repair via a SPRTN-Tdp1 axis. We discovered a Nudix homology domain (NHD) in SPRTN that mediates direct non-covalent PAR binding and is important for DPC repair. Loss of PARP1/2 activity or mutation of the SPRTN NHD leads to sustained DPCs. Single-molecule analysis revealed that SPRTN does not bind efficiently to the DPC, however after the addition of PARP1 in the presence of NAD ⁺ , SPRTN binding to the DPC was significantly increased. Our findings establish PARP1/2 enzymes as immediate DPC sensors, reveal PARylation as a signal marking DPCs for SPRTN-dependent degradation, and identify SPRTN as the first PARP-directed protease.

Insights

Poly-(ADP-ribose) polymerases (PARP1/2) detect DNA-protein crosslinks (DPCs) and signal for their repair. This discovery reveals PARP1/2 as DPC sensors and SPRTN as the first PARP-directed protease.

Area of Science:

Molecular Biology
Genetics
Biochemistry

Background:

DNA-protein crosslinks (DPCs) are toxic lesions that can cause genomic instability, premature aging, and cancer.
Existing proteases and the 26S proteasome degrade DPCs, but the detection and marking mechanisms remain unknown.

Purpose of the Study:

To elucidate the mechanism by which DNA-protein crosslinks (DPCs) are detected and marked for proteolysis.
To identify the key enzymes and pathways involved in DPC resolution.

Main Methods:

Utilized single-molecule analysis to observe protein-DNA interactions.
Investigated the role of poly-(ADP-ribose) polymerases (PARP1/2) and SPRTN in DPC repair.
Characterized the binding of SPRTN to DPCs in the presence and absence of PARP1 and NAD+.

Main Results:

Demonstrated that PARP1/2 enzymes directly sense DPCs and initiate their repair by poly(ADP-ribosyl)ation (PARylation).
Identified a Nudix homology domain (NHD) in SPRTN that binds poly(ADP-ribose) (PAR), which is crucial for DPC repair.
Showed that SPRTN binding to DPCs is significantly enhanced by PARP1 activity and PARylation.
Loss of PARP1/2 or SPRTN NHD function leads to the accumulation of DPCs.

Conclusions:

Established PARP1/2 as the primary sensors of DPCs.
Revealed PARylation as a critical signal for marking DPCs for SPRTN-dependent degradation.
Identified SPRTN as the first protease directed by PARP to resolve DPCs, highlighting a novel DNA repair pathway.

Read full analysis

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