scholarly journals Preservation of lagging strand integrity at sites of stalled replication by Pol α-primase and 9-1-1 complex

2021 ◽  
Vol 7 (21) ◽  
pp. eabf2278
Author(s):  
Robin van Schendel ◽  
Ron Romeijn ◽  
Helena Buijs ◽  
Marcel Tijsterman
Keyword(s):  
Replication Fork ◽  
Genome Duplication ◽  
De Novo ◽  
Mechanistic Model ◽  
Dna Integrity ◽  
Whole Genome Analysis ◽  
Dna Loss ◽  
Replication Intermediates ◽  
Lagging Strand ◽  
Primase Complex

During genome duplication, the replication fork encounters a plethora of obstacles in the form of damaged bases, DNA–cross-linked proteins, and secondary structures. How cells protect DNA integrity at sites of stalled replication is currently unknown. Here, by engineering “primase deserts” into the Caenorhabditis elegans genome close to replication-impeding G-quadruplexes, we show that de novo DNA synthesis downstream of the blocked fork suppresses DNA loss. We next identify the pol α-primase complex to limit deletion mutagenesis, a conclusion substantiated by whole-genome analysis of animals carrying mutated POLA2/DIV-1. We subsequently identify a new role for the 9-1-1 checkpoint clamp in protecting Okazaki fragments from resection by EXO1. Together, our results provide a mechanistic model for controlling the fate of replication intermediates at sites of stalled replication.

scholarly journals The DNA Polymerase _-Primase Complex: Multiple Functions and Interactions

2003 ◽  
Vol 3 ◽  
pp. 21-33 ◽  
Author(s):  
Marco Muzi-Falconi ◽  
Michele Giannattasio ◽  
Marco Foiani ◽  
Paolo Plevani
Keyword(s):  
Dna Polymerase ◽  
Replication Fork ◽  
De Novo ◽  
Telomere Maintenance ◽  
Cellular Processes ◽  
Eukaryotic Dna ◽  
Initiation Of Dna Replication ◽  
Lagging Strand ◽  
Primase Complex

DNA polymerase _ (pol _) holds a special position among the growing family of eukaryotic DNA polymerases. In fact, pol _ is associated with DNA primase to form a four subunit complex and, as a consequence, is the only enzyme able to start DNA synthesis de novo. Because of this peculiarity the major role of the DNA polymerase _-primase complex (pol-prim) is in the initiation of DNA replication at chromosomal origins and in the discontinuous synthesis of Okazaki fragments on the lagging strand of the replication fork. However, pol-prim seems to play additional roles in other complex cellular processes, such as the response to DNA damage, telomere maintenance, and the epigenetic control of higher order chromatin assembly.

scholarly journals Inversions with deletions and duplications.

Genetics ◽  
1995 ◽  
Vol 140 (1) ◽  
pp. 411-414 ◽  
Author(s):  
A J Gordon ◽  
J A Halliday
Keyword(s):  
Dna Replication ◽  
Replication Fork ◽  
De Novo ◽  
Leading Strand ◽  
Lagging Strand

Abstract Complex mutational events, including de novo inversion with deletion and duplication of sequence, have been observed but are difficult to model. We propose that nascent leading-strand misalignment upon the lagging-strand template during DNA replication can result in the inversion of sequence. The positioning of this misalignment and of the realignment of the leading strand back into the leading-strand template will determine if the inversion is accompanied by deletion and duplication of sequence. We suggest that such strand misalignment-realignment events may occur at the replication fork during concurrent DNA replication.

scholarly journals A nuclease-hypersensitive region forms de novo after chromosome replication.

1987 ◽  
Vol 7 (10) ◽  
pp. 3822-3825 ◽  
Author(s):  
M J Solomon ◽  
A Varshavsky
Keyword(s):  
Base Pair ◽  
Replication Origin ◽  
Replication Fork ◽  
De Novo ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Transcriptional Enhancer ◽  
Exposed Region ◽  
Infected Cells ◽  
Replication Intermediates

Regular nucleosome arrays in eucaryotic chromosomes are punctuated at specific locations, such as active promoters and replication origins, by apparently nucleosome-free sites, also called nuclease-hypersensitive, or exposed, regions. The -400-base pair-exposed region within simian virus 40 (SV40) chromosomes is present in approximately 20% of the chromosomes in lytically infected cells and encompasses the replication origin, transcriptional enhancer, and both late and early SV40 promoters. We report that nearly all SV40 chromosomes lacked the exposed region during replication and that newly formed chromosomes acquired the exposed region of the same degree as did bulk SV40 chromosomes within 1 h after replication. Furthermore, a much lower but significant level of exposure was detectable in late SV40 replication intermediates, indicating that formation of the exposed region could start within minutes after passage of the replication fork.

scholarly journals A nuclease-hypersensitive region forms de novo after chromosome replication

1987 ◽  
Vol 7 (10) ◽  
pp. 3822-3825
Author(s):  
M J Solomon ◽  
A Varshavsky
Keyword(s):  
Base Pair ◽  
Replication Origin ◽  
Replication Fork ◽  
De Novo ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Transcriptional Enhancer ◽  
Exposed Region ◽  
Infected Cells ◽  
Replication Intermediates

Regular nucleosome arrays in eucaryotic chromosomes are punctuated at specific locations, such as active promoters and replication origins, by apparently nucleosome-free sites, also called nuclease-hypersensitive, or exposed, regions. The -400-base pair-exposed region within simian virus 40 (SV40) chromosomes is present in approximately 20% of the chromosomes in lytically infected cells and encompasses the replication origin, transcriptional enhancer, and both late and early SV40 promoters. We report that nearly all SV40 chromosomes lacked the exposed region during replication and that newly formed chromosomes acquired the exposed region of the same degree as did bulk SV40 chromosomes within 1 h after replication. Furthermore, a much lower but significant level of exposure was detectable in late SV40 replication intermediates, indicating that formation of the exposed region could start within minutes after passage of the replication fork.

scholarly journals Interactions between Telomerase and Primase Physically Link the Telomere and Chromosome Replication Machinery

2002 ◽  
Vol 22 (16) ◽  
pp. 5859-5868 ◽  
Author(s):  
Saugata Ray ◽  
Zemfira Karamysheva ◽  
Libin Wang ◽  
Dorothy E. Shippen ◽  
Carolyn M. Price
Keyword(s):  
De Novo ◽  
Telomerase Activity ◽  
Nuclear Antigen ◽  
Replication Machinery ◽  
Developmentally Regulated ◽  
Coordinate Regulation ◽  
Euplotes Crassus ◽  
Order Complexes ◽  
Proliferating Cell ◽  
Lagging Strand

ABSTRACT In the ciliate Euplotes crassus, millions of new telomeres are synthesized by telomerase and polymerase α-primase during macronuclear development in mated cells. Concomitant with de novo telomere formation, telomerase assembles into higher-order complexes of 550 kDa, 1,600 kDa, and 5 MDa. We show here that telomerase is physically associated with the lagging-strand replication machinery in these complexes. Antibodies against DNA primase precipitated telomerase activity from all three complexes from mated cells but not the 280-kDa telomerase complex from vegetatively growing cells. Moreover, when telomerase was affinity purified, primase copurified with enzyme from mated cells but not with the 280-kDa vegetative complex. Thus, the association of telomerase and primase is developmentally regulated. Intriguingly, PCNA (proliferating cell nuclear antigen) was also found in the 5-MDa complex from mated cells. We therefore speculate that this complex is a complete telomere synthesis machine, while the smaller complexes are assembly intermediates. The physical association of telomerase and primase explains the coordinate regulation of telomeric G- and C-strand synthesis and the efficiency of telomere addition in E. crassus.

Mitochondrial topoisomerase II activity is essential for kinetoplast DNA minicircle segregation

1994 ◽  
Vol 14 (6) ◽  
pp. 3660-3667
Author(s):  
T A Shapiro
Keyword(s):  
Replication Fork ◽  
Topoisomerase Ii ◽  
Potent Inhibitor ◽  
Late Replication ◽  
Kinetoplast Dna ◽  
Two Dimensional Gel Electrophoresis ◽  
Trypanosoma Equiperdum ◽  
Replication Intermediates ◽  
Novel Structures

Etoposide, a nonintercalating antitumor drug, is a potent inhibitor of topoisomerase II activity. When Trypanosoma equiperdum is treated with etoposide, cleavable complexes are stabilized between topoisomerase II and kinetoplast DNA minicircles, a component of trypanosome mitochondrial DNA (T. A. Shapiro, V. A. Klein, and P. T. Englund, J. Biol. Chem. 264:4173-4178, 1989). Etoposide also promotes the time-dependent accumulation of small minicircle catenanes. These catenanes are radiolabeled in vivo with [3H]thymidine. Dimers are most abundant, but novel structures containing up to five noncovalently closed minicircles are detectable. Analysis by two-dimensional gel electrophoresis and electron microscopy indicates that dimers joined by up to six interlocks are late replication intermediates that accumulate when topoisomerase II activity is blocked. The requirement for topoisomerase II is particularly interesting because minicircles do not share the features postulated to make this enzyme essential in other systems: for minicircles, the replication fork is unidirectional, access to the DNA is not blocked by nucleosomes, and daughter circles are extensively nicked and (or) gapped.

scholarly journals Structure-Specific Endonucleases and the Resolution of Chromosome Underreplication

Genes ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 232 ◽  
Author(s):  
Benoît Falquet ◽  
Ulrich Rass
Keyword(s):  
Sister Chromatid ◽  
Replication Fork ◽  
Genome Stability ◽  
Molecular Mechanisms ◽  
Chromosome Breakage ◽  
Repair Synthesis ◽  
Daughter Cells ◽  
Oncogene Activation ◽  
Dna Repair Synthesis ◽  
Replication Intermediates

Complete genome duplication in every cell cycle is fundamental for genome stability and cell survival. However, chromosome replication is frequently challenged by obstacles that impede DNA replication fork (RF) progression, which subsequently causes replication stress (RS). Cells have evolved pathways of RF protection and restart that mitigate the consequences of RS and promote the completion of DNA synthesis prior to mitotic chromosome segregation. If there is entry into mitosis with underreplicated chromosomes, this results in sister-chromatid entanglements, chromosome breakage and rearrangements and aneuploidy in daughter cells. Here, we focus on the resolution of persistent replication intermediates by the structure-specific endonucleases (SSEs) MUS81, SLX1-SLX4 and GEN1. Their actions and a recently discovered pathway of mitotic DNA repair synthesis have emerged as important facilitators of replication completion and sister chromatid detachment in mitosis. As RS is induced by oncogene activation and is a common feature of cancer cells, any advances in our understanding of the molecular mechanisms related to chromosome underreplication have important biomedical implications.

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