Journal ArticleDOI
RPA governs endonuclease switching during processing of Okazaki fragments in eukaryotes
TLDR
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).Abstract:
Extensive work on the maturation of lagging strands during the replication of simian virus 40 DNA suggests that the initiator RNA primers of Okazaki fragments are removed by the combined action of two nucleases, RNase HI and Fen1, before the Okazaki fragments join1,2,3,4,5 Despite the well established in vitro roles of these two enzymes6, genetic analyses in yeast revealed that null mutants of RNase HI and/or Fen1 are not lethal7,8,9, suggesting that an additional enzymatic activity may be required for the removal of RNA One such enzyme is the Saccharomyces cerevisiae Dna2 helicase10,11,12/endonuclease12, which is essential for cell viability13,14 and is well suited to removing RNA primers of Okazaki fragments15 In addition, Dna2 interacts genetically and physically with several proteins involved in the elongation or maturation of Okazaki fragments10,16 Here we show that the endonucleases Dna2 and Fen1 act sequentially to facilitate the complete removal of the primer RNA The sequential action of these enzymes is governed by a single-stranded DNA-binding protein, replication protein-A (RPA) Our results demonstrate that the processing of Okazaki fragments in eukaryotes differs significantly from, and is more complicated than, that occurring in prokaryotes We propose a novel biochemical mechanism for the maturation of eukaryotic Okazaki fragmentsread more
Citations
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Proliferating cell nuclear antigen (PCNA): a dancer with many partners.
Giovanni Maga,Ulrich Hübscher +1 more
TL;DR: Structural and biochemical studies are starting to provide a first glimpse of how both PCNA temporally and spatially organise their functions and how both tasks can be achieved.
Journal ArticleDOI
Sgs1 helicase and two nucleases Dna2 and Exo1 resect DNA double-strand break ends.
TL;DR: Monitoring 5'-strand resection at inducible DSB ends in yeast and identified proteins required for two stages of resection shows that the Mre11-Rad50-Xrs2 complex (MRX) initiates 5' degradation, whereas Sgs1 and Dna2 degrade 5' strands exposing long 3' strands.
Journal ArticleDOI
BLM–DNA2–RPA–MRN and EXO1–BLM–RPA–MRN constitute two DNA end resection machineries for human DNA break repair
Amitabh V. Nimonkar,Jochen Genschel,Eri Kinoshita,Piotr Polaczek,Judith L. Campbell,Claire Wyman,Paul Modrich,Stephen C. Kowalczykowski +7 more
TL;DR: Two of the core machineries that initiate recombinational DNA repair in human cells are established: Bloom helicase and DNA2 nuclease, and the complex comprising MRE11, RAD50, and NBS1 (MRN).
Journal ArticleDOI
Trex1 Exonuclease Degrades ssDNA to Prevent Chronic Checkpoint Activation and Autoimmune Disease
TL;DR: It is reported that Trex1, ordinarily associated with the endoplasmic reticulum (ER), relocalizes to the S phase nucleus after gamma irradiation or hydroxyurea treatment and acts on a single-stranded DNA polynucleotide species generated from processing of aberrant replication intermediates to attenuate DNA damage checkpoint signaling and prevent pathological immune activation.
Journal ArticleDOI
DNA end resection by Dna2-Sgs1-RPA and its stimulation by Top3-Rmi1 and Mre11-Rad50-Xrs2
Petr Cejka,Elda Cannavo,Piotr Polaczek,Taro Masuda-Sasa,Subhash Pokharel,Judith L. Campbell,Stephen C. Kowalczykowski +6 more
TL;DR: It is established that Dna2, Sgs1 and RPA constitute a minimal protein complex capable of DNA resection in vitro and that both the topoisomerase 3 and Rmi1 complex and the Mre11–Rad50–Xrs2 complex (MRX) have important roles as stimulatory components.
References
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Journal ArticleDOI
REPLICATION PROTEIN A: A Heterotrimeric, Single-Stranded DNA-Binding Protein Required for Eukaryotic DNA Metabolism
TL;DR: Replication protein A (RPA) is a single-stranded DNA-binding protein that is required for multiple processes in eukaryotic DNA metabolism, including DNA replication, DNA repair, and recombination.
Journal ArticleDOI
The dna replication fork in eukaryotic cells
Shou Waga,Bruce Stillman +1 more
TL;DR: Biochemical studies, principally of plasmid DNAs containing the Simian Virus 40 origin of DNA replication, and yeast genetic studies have uncovered the fundamental mechanisms of replication fork progression.
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Anatomy of a DNA replication fork revealed by reconstitution of SV40 DNA replication in vitro
Shou Waga,Bruce Stillman +1 more
TL;DR: Complete enzymatic replication of DNA from the simian virus 40 origin has been reconstituted with T antigen and highly purified cellular proteins to replicate both strands of the double helix conjointly.
Journal ArticleDOI
The FEN-1 family of structure-specific nucleases in eukaryotic dna replication, recombination and repair
TL;DR: The crystal structures of two enzymes in the F EN‐1 nuclease family have been solved and they provide a structural basis for the interesting steric requirements of FEN‐1 substrates.