Biology subjects

Simonson, Q.

Publications and source records attributed to Simonson, Q..

2 recordsLinked to original sources

bioRxiv2026

PARP1-mediated PARylation of SPRTN restrains its DNA-protein crosslink repair activity

SPRTN is a DNA-dependent metalloprotease that resolves DNA-protein crosslinks, but how its activity is restrained on chromatin remains unclear. Here we show that SPRTN is PARylated in a PARP1- and HPF1-dependent manner. Mass spectrometry datasets identify seven modified residues in the C-terminal region, and substituting them (SPRTN-PARless) strongly reduces PARylation. The Nudix homology domain is required for SPRTN to interact with PARP1 and for efficient PARylation. SPRTN-PARless accumulates faster and to higher levels at laser-induced DNA damage than wild-type SPRTN. PARylation reduces single-stranded DNA binding of both cell-derived and purified SPRTN, and PARG treatment reverses this effect for cell-derived protein. SPRTN-PARless shows increased autocleavage and accelerates clearance of camptotheci-induced TOP1 cleavage complexes. These findings suggest that PARylation acts as negative feedback on SPRTN after its PAR-dependent recruitment, restraining its DNA engagement and proteolytic activity.

molecular biology↗

bioRxiv2026

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

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.

molecular biology↗