Related Experiment Video

Updated: Jan 16, 2026

Strand-Specific Analysis of Proteins at Replicating DNA Strands by Enrichment and Sequencing of Protein-Associated Nascent DNA Method
08:53

Strand-Specific Analysis of Proteins at Replicating DNA Strands by Enrichment and Sequencing of Protein-Associated Nascent DNA Method

Published on: May 2, 2025

903

PARP1 auto-modification promotes faithful Okazaki fragment processing and limits replication fork speed

Jonas D Elsborg1, Sebastian H N Munk2, Alba Adelantado-Rubio2

  • 1Department of Cellular and Molecular Medicine, Novo Nordisk Foundation Center for Protein Research, Proteomics Program, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

Molecular Cell
|October 3, 2025
PubMed

Insights

Poly(ADP-ribose) polymerase inhibitors target cancer by exploiting synthetic lethality. A new study reveals PARP1 auto-modification, distinct from its enzymatic activity, is crucial for DNA repair and preventing replication stress.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • Poly(ADP-ribose) polymerase (PARP) inhibitors are effective cancer treatments for tumors with homologous recombination deficiencies, utilizing synthetic lethality.
  • PARP1 is a key enzyme in DNA break response, performing auto-modification and modifying other proteins to aid repair.
  • Dissecting the roles of PARP1 auto-modification versus its catalytic activity is challenging due to current inhibitor mechanisms.

Purpose of the Study:

  • To differentiate the functional roles of PARP1 auto-modification and catalytic activity in DNA repair and cellular response.
  • To investigate the impact of PARP1 auto-modification on DNA replication and stress response.
  • To explore novel synthetic lethality interactions involving PARP1 auto-modification.

Main Methods:

  • Proteomics and site-directed mutagenesis were employed to create a PARP1 mutant with impaired auto-modification but retained catalytic activity.
  • The functional consequences of this separation-of-function mutant were analyzed in response to DNA damage.
  • Synthetic lethality was assessed by combining loss of PARP1 auto-modification with inhibition of other cellular processes, such as FEN1 activity.

Main Results:

  • A PARP1 mutant deficient in auto-modification, but catalytically active, was generated.
  • PARP1 auto-modification was found to impede DNA replication fork progression but is not essential for recruiting repair factors.
  • Auto-modification facilitates PARP1 release from DNA breaks, prevents replication stress, and is implicated in Okazaki fragment processing, showing synthetic lethality with FEN1 inhibition.

Conclusions:

  • PARP1 auto-modification has distinct roles separate from its catalytic activity, influencing replication fork dynamics and protein release at DNA breaks.
  • Trapping PARP1 at DNA break sites hinders repair factor access, contributing to PARP inhibitor cytotoxicity.
  • Targeting PARP1 auto-modification presents a potential new avenue for cancer therapy, particularly in combination strategies.
Keywords:
ADP-ribosylationDNA replication forkOkazaki fragmentPARP inhibitorPARP1PTMauto-modificationelectron-transfer dissociationproteomics resourcereplication stress

More Related Videos

Detection of Post-Replicative Gaps Accumulation and Repair in Human Cells Using the DNA Fiber Assay10:32

Detection of Post-Replicative Gaps Accumulation and Repair in Human Cells Using the DNA Fiber Assay

Published on: February 3, 2022

7.7K
Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase07:27

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Published on: April 29, 2010

14.0K

Related Concept Videos

Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
6.3K
Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

2.3K
The DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication...
40.4K
The DNA Replication Fork01:02

The DNA Replication Fork

18.1K
The Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with...
38.1K
Proofreading01:31

Proofreading

Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the template DNA strand. DNA polymerase has a higher affinity to add the correct base and ensures fidelity during DNA replication. Furthermore,  it exhibits proofreading activity during replication, using an exonuclease domain that cuts off incorrect nucleotides from the nascent DNA strand.
Errors During Replication are Corrected by the DNA Polymerase...
8.7K