Dna2 on the road to Okazaki fragment processing and genome stability in eukaryotes

  title={Dna2 on the road to Okazaki fragment processing and genome stability in eukaryotes},
  author={Young-Hoon Kang and Chul-Hwan Lee and Yeon-Soo Seo},
  journal={Critical Reviews in Biochemistry and Molecular Biology},
  pages={71 - 96}
DNA replication is a primary mechanism for maintaining genome integrity, but it serves this purpose best by cooperating with other proteins involved in DNA repair and recombination. Unlike leading strand synthesis, lagging strand synthesis has a greater risk of faulty replication for several reasons: First, a significant part of DNA is synthesized by polymerase α, which lacks a proofreading function. Second, a great number of Okazaki fragments are synthesized, processed and ligated per cell… 

Mechanism of Lagging-Strand DNA Replication in Eukaryotes.

This chapter focuses on the enzymes and mechanisms involved in lagging-strand DNA replication in eukaryotic cells and how each of the millions of Okazaki fragments in a mammalian cell is primed by the primase subunit and further extended by its polymerase sub unit.

Okazaki fragment metabolism.

Genetic analyses and reconstitution experiments identified proteins and multiple pathways responsible for maturation of the lagging strand, which involves many enzymes, possibly three pathways, and regulation that can shift from high efficiency to high fidelity.

The Saccharomyces cerevisiae Dna2 can function as a sole nuclease in the processing of Okazaki fragments in DNA replication

A model where Dna2 alone is responsible for cleaving of RPA-bound long flaps, while Fen1 or exonuclease 1 (Exo1) cleave short flaps is proposed, arguing that Dna1 can function in a separate, rather than in a Fen1-dependent pathway.

Eukaryotic DNA Replication Fork.

The preponderance of evidence supports a model in which DNA polymerase ε (Pol ε) carries out the bulk of leading strand DNA synthesis at an undisturbed replication fork, with an emphasis on the enzymes that synthesize DNA and repair discontinuities on the lagging strand of the replication fork.

Okazaki Fragment Processing-independent Role for Human Dna2 Enzyme during DNA Replication*

The findings suggest that the genomic instability observed in hDna2-depleted cells does not arise from defective OF maturation and that hDNA2 plays a role in DNA replication that is distinct from FEN1 and Of maturation.

Dna2 Exhibits a Unique Strand End-dependent Helicase Function*

This is the first description of a eukaryotic helicase that cannot load onto its tracking strand internally but instead must enter from the end, and likely helps the helicase to coordinate with the Dna2 nuclease function to prevent creation of undesirably long flaps during DNA transactions.

Rad53 arrests leading and lagging strand DNA synthesis via distinct mechanisms in response to DNA replication stress

  • Richard HeZhiguo Zhang
  • Biology
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2022
eSPAN and BrdU‐IP‐ssSeq, strand‐specific sequencing technologies that permit analysis of protein localization and DNA synthesis at individual strands in budding yeast, are discussed and it is shown that under replication stress Rad53 stalls DNA synthesis on both leading and lagging strands.

The wonders of flap endonucleases: structure, function, mechanism and regulation.

A detailed review of FEN structure is undertaken to show how DNA substrate recognition occurs and how FEN achieves cleavage at a single phosphate diester, and a proposed double nucleotide unpairing trap (DoNUT) is discussed with regards to FEN and has relevance to the wider 5' nuclease superfamily.

hDNA2 nuclease/helicase promotes centromeric DNA replication and genome stability

It is shown that DNA2 binds preferentially to centromeric DNA, and the DNA2 inhibitor C5 mimics DNA2 knockout and synergistically kills cancer cells when combined with an ATR inhibitor, providing mechanistic insights into how DNA2 supports replication of centromic DNA.

DNA2 in Chromosome Stability and Cell Survival—Is It All about Replication Forks?

It is proposed that the major cellular defects associated with DNA2 dysfunction, and the links that exist with human disease, can be rationalized through the fundamental importance of DNA2-dependent RF recovery to genome duplication.



Replication of the lagging strand: a concert of at least 23 polypeptides.

This minireview summarizes the current knowledge of the components involved in the execution and regulation of DNA replication at the lagging strand of the replication fork.

DNA replication fork proteins.

This review will summarize the properties of DNA replication proteins that function exclusively at the replication fork that have been shown to be essential in sensing and transducing DNA damages through the checkpoint cascade pathways.

RPA governs endonuclease switching during processing of Okazaki fragments in eukaryotes

It is shown that the endonucleases Dna2 and Fen1 act sequentially to facilitate the complete removal of the primer RNA in Okazaki fragments, governed by a single-stranded DNA-binding protein, replication protein-A (RPA).

DNA Polymerases that Propagate the Eukaryotic DNA Replication Fork

The burden of evidence suggests that DNA polymerase ε normally replicates this strand, but under conditions of dysfunction, DNA polymerases δ may substitute, and this strand is thought to function at the eukaryotic DNA replication fork.

The structure-specific endonuclease Mus81 contributes to replication restart by generating double-strand DNA breaks

It is suggested that Mus81 suppresses chromosomal instability by converting potentially detrimental replication-associated DNA structures into intermediates that are more amenable to DNA repair.

Idling by DNA polymerase delta maintains a ligatable nick during lagging-strand DNA replication.

These studies highlight a remarkably efficient mechanism for Okazaki fragment maturation in which Pol delta by default displaces 2-3 nt of any downstream RNA or DNA it encounters.

Polymerase Dynamics at the Eukaryotic DNA Replication Fork*

  • P. Burgers
  • Biology
    Journal of Biological Chemistry
  • 2009
This review discusses recent insights in the roles of DNA polymerases (Pol) δ and ϵ in eukaryotic DNA replication. A growing body of evidence specifies Pol ϵ as the leading strand DNA polymerase and

Okazaki Fragment Maturation in Yeast

Results suggest that FEN1, but not DNA ligase, is a stable component of the maturation complex and shortened the nick-translation patch to 4–6 nt from 8–12 nt with equimolar ligase.

Multiple Functions of DNA Polymerases

The properties and functions of DNA polymerases focusing on yeast and mammalian cells but paying special attention to the plant enzymes and the special circumstances of replication and repair in plant cells are reviewed.

Mechanisms of Dealing with DNA Damage-Induced Replication Problems

How checkpoint signaling adjusts cell cycle progression to the emergency situation and the use of specialized pathways promoting replication restart is reviewed, which gives cells more time to deal with the damage.