Related Experiment Video
Updated: May 8, 2026
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
PARP1-mediated 5' flap dynamics facilitate Okazaki fragment maturation.
Guojun Shi1, Yixing Wang1, Yao Yan1
1Department of Cancer Genetics and Epigenetics, City of Hope Beckman Research Institute, 1500 East Duarte Road, Duarte, CA 91010, USA.
Biorxiv : the Preprint Server for Biology
|May 7, 2026
Summary
Poly (ADP-ribose) polymerase 1 (PARP1) plays dual roles in Okazaki fragment maturation (OFM) by regulating DNA synthesis and flap processing. PARP1 ensures efficient DNA repair and cell viability by controlling flap dynamics during lagging-strand synthesis.
Area of Science:
- Molecular Biology
- DNA Replication
- Enzymology
Background:
- Okazaki fragment maturation (OFM) is critical for lagging-strand DNA synthesis.
- The precise regulation of enzyme recruitment during OFM is essential for genomic stability.
- Poly (ADP-ribose) polymerase 1 (PARP1) has been implicated in OFM, but its specific functions are not fully understood.
Purpose of the Study:
- To elucidate the context-dependent functions of PARP1 during Okazaki fragment maturation.
- To understand how PARP1 regulates DNA synthesis and flap processing in different cellular conditions.
- To investigate the role of PARP1 in maintaining cell viability through efficient OFM.
Main Methods:
- Co-localization studies of PARP1 with PCNA during S phase.
- Analysis of DNA synthesis and flap formation in wild-type and LIG1-deficient cells.
- Investigation of PARP1's role in recruiting LIG3 and DNA2 for DNA repair.
Main Results:
- Under physiological conditions, PARP1 restrains Pol δ-PCNA-mediated strand-displacement synthesis, preventing long 5' flap formation.
- In LIG1-deficient cells, PARP1 promotes LIG3 recruitment for ligation and DNA2 for long 5' flap processing.
- PARP1 inhibition shows synthetic lethality with DNA ligase 1 or DNA2 inhibition.
Conclusions:
- PARP1 exhibits context-dependent functions in regulating 5' flap dynamics during OFM.
- PARP1 ensures efficient OFM and cell viability by fine-tuning enzyme recruitment and flap processing.
- PARP1's distinct roles highlight its importance in maintaining genome integrity during DNA replication.
Related Concept Videos
02:37Restarting 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, a...
01:59Lagging Strand Synthesis
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
01:59Lagging Strand Synthesis
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...
03:01The 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 the...
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 the...
01:02Long-patch Base Excision Repair
Since the discovery of the two BER pathways, there has been a debate about how a cell chooses one pathway over the other and the factors determining this selection. Numerous in vitro experiments have pointed out multiple determinants for the sub-pathway selection. These are:
01:31Proofreading
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 Enzyme
Errors During Replication are Corrected by the DNA Polymerase Enzyme