Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DNA replication”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1986

Synthesis of bacteriophage phi X174 in vitro: mechanism of switch from DNA replication to DNA packaging.

Replication of a replicative form DNA of bacteriophage phi X174 initiates by rolling-circle synthesis of the viral DNA followed by discontinuous synthesis of the complementary DNA. Gene C protein of phi X174, which is involved in DNA packaging, inhibits the rolling-circle DNA synthesis by binding to the initiation complex in vitro. The gene C protein-associated initiation complex can synthesize and package the viral DNA to produce infectious phage when supplemented with phi X174 gene J protein and the prohead. Multiple rounds of phage synthesis occur without dissociation of the gene C protein from the complex. These results indicate that gene C protein is central in the switch from replication of a replicative form DNA to synthesis and concomitant packaging of viral DNA into phage capsid, which occurs in the late stage of infection.

Bacteriophage phi X 174↗
PubMed1997

A role for DNA primase in coupling DNA replication to DNA damage response.

The temperature-sensitive yeast DNA primase mutant pri1-M4 fails to execute an early step of DNA replication and exhibits a dominant, allele-specific sensitivity to DNA-damaging agents. pri1-M4 is defective in slowing down the rate of S phase progression and partially delaying the G1-S transition in response to DNA damage. Conversely, the G2 DNA damage response and the S-M checkpoint coupling completion of DNA replication to mitosis are unaffected. The signal transduction pathway leading to Rad53p phosphorylation induced by DNA damage is proficient in pri1-M4, and cell cycle delay caused by Rad53p overexpression is counteracted by the pri1-M4 mutation. Altogether, our results suggest that DNA primase plays an essential role in a subset of the Rad53p-dependent checkpoint pathways controlling cell cycle progression in response to DNA damage.

Blotting, Western↗
PubMed1981

An autoradiographic demonstration of nuclear DNA replication by DNA polymerase alpha and of mitochondrial DNA synthesis by DNA polymerase gamma.

The incorporation of thymidine into the DNA of eukaryotic cells is markedly depressed, but not completely inhibited, by aphidicolin, a highly specific inhibitor of DNA polymerase alpha. An electron microscope autoradiographic analysis of the synthesis of nuclear and mitochondrial DNA in vivo in Concanavalin A stimulated rabbit spleen lymphocytes and in Hamster cell cultures, in the absence and in the presence of aphidicolin, revealed that aphidicolin inhibits the nuclear but not the mitochondrial DNA replication. We therefore conclude that DNA polymerase alpha performs the synchronous bidirectional replication of nuclear DNA and that DNA polymerase gamma, the only DNA polymerase present in the mitochondria, performs the "strand displacement" DNA synthesis of these organelles.

Animals↗
PubMed1998

Stoichiometry and mechanism of assembly of SV40 T antigen complexes with the viral origin of DNA replication and DNA polymerase alpha-primase.

The interactions of simian virus 40 (SV40) large T antigen with DNA carrying the viral origin of DNA replication, as well as its interactions with cellular replication proteins, have been investigated by using fluorescent ATP analogues as specific probes. The enhanced fluorescence of 3'(2')-O-(2,4, 6-trinitrophenyl)adenosine diphosphate (TNP-ADP) induced by T antigen binding to the nucleotide was decreased upon binding of T antigen to origin DNA. Similarly, the enhanced fluorescence induced by T antigen binding to TNP-ADP or TNP-ATP was decreased upon binding to human DNA polymerase alpha-primase (pol alpha), but not to replication protein A (RPA). Fluorescence titrations revealed noncompetitive inhibition of TNP-ADP binding by origin DNA, and noncompetitive inhibition of TNP-ADP and TNP-ATP binding by pol alpha, suggesting that T antigen complexed with either origin DNA or pol alpha was not able to bind the TNP nucleotide. From these titrations, we have measured a binding stoichiometry of 11.5 +/- 0.8 T antigen monomers per viral origin DNA, in agreement with the double hexamer assembly of T antigen on the origin as reported earlier. The stoichiometry of pol alpha binding to T antigen was measured to be 5.5 +/- 0.6 mol of T antigen per mole of pol alpha. While monomeric T antigen-nucleotide complex was a preferred ligand over free T antigen in the double hexamer assembly reaction, preformed T antigen hexamers were incapable of forming double hexamers on the DNA. The results support a model in which double hexamer assembly on the viral origin occurs by successive binding of 12 free T antigen or monomeric T-nucleotide complexes to the DNA. In contrast with this stepwise assembly of T antigen monomers on DNA, hexameric T antigen was able to bind directly to pol alpha with concomitant release of the bound TNP nucleotide. The possible implications of these results for the mechanism of initiation of SV40 DNA replication are discussed.

Antigens, Polyomavirus Transforming↗
PubMed1993

DNA replication in fertilized eggs of the starfish Asterina pectinifera.

Early starfish embryos were labeled with 5-bromo-2'-deoxyuridine (BrdU; the thymidine analogue) for 3-4 min of pulse, and the BrdU incorporated into newly replicated DNA was immunocytochemically detected with anti-BrdU antibody. Series of optical sections of the stained embryos observed with a confocal laser scanning microscope (CLSM) were collected, and three-dimensional images of the chromatin and the incorporated BrdU were reconstructed on a computer display. The distribution of the DNA replication sites and the chromatin structure were investigated from a three-dimensional point of view. The oocytes fertilized during maturation and the eggs fertilized after maturation were examined for the timing of S phase, DNA replication pattern, and chromatin distribution in the nucleus. Duration of the first S phase between the two types of embryos differed in the first S phase, but was the same in the second and third S phases. We observed a successive change in the distribution of DNA replication sites from a "uniform" to a "condensing" pattern during a single S phase traverse, except in the first S phase of the eggs fertilized after maturation. These two patterns of DNA replication almost coincided with chromatin visualized by anti-single-stranded DNA antiserum. The apparent change in the pattern of DNA replication sites thus simply reflects the change in the spatial distribution of chromatin. The spatial pattern of DNA replication at the first S phase of the eggs fertilized after maturation was unique in that the whole nucleus was a mosaic of two distinct regions, each supposedly derived from the female and male pronuclei. The putative female region had a fibrillar pattern of DNA replication sites confined to the periphery of the nucleus, while the male region showed condensed sites of DNA replication, which persisted longer than the sites in the female pronuclear region. We discuss such a singularity of the first S phase in starfish eggs on the basis of the temporal relation between the progress of maturation and the time of activation.

Animals↗
PubMed1990

An abnormal profile of DNA replication intermediates in Bloom's syndrome.

Bloom's syndrome (BS) cells display a characteristic genomic instability, notably an elevated frequency of sister-chromatid exchange. Replicating DNA in cultured BS cells was labeled with [3H]thymidine using several time schedules. Separation of DNA in agarose gels showed high molecular weight DNA and three classes of DNA replication intermediates: 20-kilobase DNA, 10-kilobase DNA, and Okazaki fragments. In contrast newly replicated DNA from normal cells showed no 20-kilobase DNA replication intermediates. Certain BS cells, exceptional in that their characteristic genomic instability has for unknown reasons been corrected, also differed from normal cells in having the 20-kilobase intermediate, but they differed from both normal cells and the other (the uncorrected) BS cells in lacking the 10-kilobase DNA replication intermediates.

Aphidicolin↗
PubMedDate not supplied

[Stimulation of replicative DNA synthesis by eukaryotic proteins bound to single-stranded DNA].

The paper deals with the effect of the single-strand (ss) DNA-binding proteins (SSB-proteins) from the Ehrlich ascites tumor (EAT) cells and from the eggs of silkworm, as well as the mouse serum blood proteins, having preferential affinity to ss DNA, on the DNA replicative synthesis in the EAT cells permeable for the macromolecules, and, for the silkworm proteins and on the DNA replicative synthesis in the nuclei from the eggs of silkworm proteins and on the DNA replicative synthesis in the nuclei from the eggs of silkworm permeable for macromolecules. SSB-proteins of EAT to considerable extent stimulated the DNA synthesis. At the same time, the other proteins (from the silkworm and from the serum) activated the DNA synthesis in the permeable cells to the less extent. It was found that SSB-proteins from the silkworm had a 1.5-13 fold stimulating effect on the DNA replicative synthesis in the homologous system (in the permeable nuclei). If the permeability for the macromolecules of the cells and nuclei treatment with Triton X-100 may be different, it is supposed that the activation of the DNA synthesis by the exogenous proteins depends on the homologous system of the DNA replicative complex. It is possible that the effect of the serum proteins on the DNA synthesis is connected with the masking of the ss regions of DNA which inhibited DNA-polymerase alpha. Perhaps the mechanisms of the activation of the DNA replicative synthesis by the proteins in vitro with the purified DNA polymerase alpha and in vivo are of different nature and are conditioned by homology of the deoxyribonucleoproteins.

Animals↗
PubMed1981

DNA polymerase accuracy and spontaneous mutation rates: frequencies of purine.purine, purine.pyrimidine, and pyrimidine.pyrimidine mismatches during DNA replication.

DNA from the am16 mutant of bacteriophage phi X174 may be replicated in vitro and expressed in vivo to give five classes of revertants. Each class may be specifically induced by the appropriate biasing of the concentrations of deoxynucleoside triphosphates in a predictable manner. The frequency of each reversion follows a kinetic rate equation relating it to the concentrations of the triphosphates involved in the substitution. The reversions corresponding to TAG leads to GAG, AAG, CAG, TGG, and TCG are calculated to occur with frequencies of 5 X 10(-7), 4 X 10(-7), 4 X 10(-7), approximately 2 X 10(-7), and approximately 5 X 10(-9), respectively, at the concentration of triphosphates found in vivo. The frequencies are in the range found for the reversion of the phage in vivo and so are consistent with errors in nucleotide selection by DNA polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) III being largely responsible for the rate of spontaneous mutation in vivo. The relative frequency of mispairing leading to misincorporation is: purine.purine approximately purine.pyrimidine much greater than pyrimidine.pyrimidine, confirming predictions from model-building studies that transversions arise through purine.purine mismatches.

Bacteriophage phi X 174↗
PubMed1981

Association of newly replicated DNA with the nuclear matrix of Physarum polycephalum.

We have studied the role of the nuclear matrix in DNA replication in a naturally synchronized eucaryote, Physarum polycephalum. When P. polycephalum. When P. polycephalum macroplasmodia were pulse labeled with 3H-thymidine, the DNA remaining tightly associated with the matrix was highly enriched in newly synthesized DNA. This enrichment was found both in nuclei that had just initiated DNA replication as well as in nuclei isolated later during S phase. Pulse chase experiments showed that the association of newly replicated DNA with the matrix is transient, since most of the newly replicated DNA could be chased from the matrix by incubating pulse labeled macroplasmodia in media containing unlabeled thymidine. Studies measuring the size distribution of the matrix DNA supported the hypothesis that replication forks are attached to the nuclear matrix. Reconstitution controls indicated that these results were unlikely to be due to preferential, nonspecific binding of nascent DNA to the matrix during the extraction procedures. These results with P. polycephalum in combination with previous studies in non-synchronized rodent cells, suggest that the association of newly replicated DNA with the nuclear matrix may be a general feature of eucaryotic DNA replication.

Cell Cycle↗
PubMed1966

Enzymatic mechanisms of DNA replication.

DNA polymerases purified from several sources are characterized by replication of the 3'-hydroxy-terminated strand of a helical template. Failure to achieve simultaneous replication of the 5'-strand leads to aberrations in the synthesized DNA, described as nondenaturability and branching. Aberrations in synthesized DNA were not observed when (a) the 5'-strand was destroyed by a specific nuclease during the course of replication or (b) a single-stranded (circular) phage (M13) DNA served as template. Replication of a single-stranded, circular DNA produced a helical product, but the nature of initiation of a new strand by the circular template remains to be explained. Hypothetical mechanisms for simultaneous replication of the 5'-strand are presented as is the possibility that the tertiary structure of the DNA, as for example, a circular form of the helix, is of prime importance in in vivo replication.

Bacteriophages↗
PubMed1975

Adenovirus type 2 DNA replication. II. Termini of DNA replication.

Complete, mature adenovirus type 2 DNA molecules were isolated from virus-infected HeLa cells, pulse-labeled at 20 h postinfection in [3H]thymidine pulses shorter than the time necessary for one round of viral DNA replication. After digestion with the restriction endonucleases Eco RI, Hpa I, and Hind III, a temporal order of synthesis of different regions of the viral genome was established from the relative specific radioactivities in the restriction enzyme fragments. A comparison with the physical order of these fragments revealed the existence of two termini of DNA replication towards both the molecular right and left ends, respectively, of the viral chromosome.

Adenoviridae↗
PubMed1978

DNA replication in Physarum polycephalum: bidirectional replication of DNA within replicons.

The direction of replication of DNA within replicons of Physarum polycephalum was studied by pulse-labelling with 5-bromouracil-deoxyriboside (BrdUrd) and 3H-adenosine deoxyriboside (dAdo), followed by ultraviolet- (UV) -photolysis and analysis of molecular weights of single strand DNA fragments on alkaline sucrose gradients. Newly made DNA within replicons at all stages of completion is split in two equal halves upon UV irradiation when BrdUrd was given at the time of initiation of DNA synthesis. This shows that replication within replicons of Physarum polycephalum starts at an origin located in the center of each unit, proceeding bidirectionally from this origin.

Bromodeoxyuridine↗
PubMed1997

Proteolysis and tyrosine phosphorylation of p34cdc2/cyclin B. The role of MCM2 and initiation of DNA replication to allow tyrosine phosphorylation of p34cdc2.

Previously, it has been shown that Aspergillus cells lacking the function of nimQ and the anaphase-promoting complex (APC) component bimEAPC1 enter mitosis without replicating DNA. Here nimQ is shown to encode an MCM2 homologue. Although mutation of nimQMCM2 inhibits initiation of DNA replication, a few cells do enter mitosis. Cells arrested at G1/S by lack of nimQMCM2 contain p34(cdc2)/cyclin B, but p34(cdc2) remains tyrosine dephosphorylated, even after DNA damage. However, arrest of DNA replication using hydroxyurea followed by inactivation of nimQMCM2 and bimEAPC1 does not abrogate the S phase arrest checkpoint over mitosis. nimQMCM2, likely via initiation of DNA replication, is therefore required to trigger tyrosine phosphorylation of p34(cdc2) during the G1 to S transition, which may occur by inactivation of nimTcdc25. Cells lacking both nimQMCM2 and bimEAPC1 are deficient in the S phase arrest checkpoint over mitosis because they lack both tyrosine phosphorylation of p34(cdc2) and the function of bimEAPC1. Initiation of DNA replication, which requires nimQMCM2, is apparently critical to switch mitotic regulation from the APC to include tyrosine phosphorylation of p34(cdc2) at G1/S. We also show that cells arrested at G1/S due to lack of nimQMCM2 continue to replicate spindle pole bodies in the absence of DNA replication and can undergo anaphase in the absence of APC function.

Amino Acid Sequence↗
PubMed1985

The origin of adenovirus DNA replication: minimal DNA sequence requirement in vivo.

Adenovirus mini-chromosomes which contain two cloned, inverted adenovirus termini replicate in vivo when supplied with non-defective adenovirus as a helper. This system has been used to define the minimum cis acting DNA sequences required for adenovirus DNA replication in vivo. Deletions into each end of the adenovirus inverted terminal repeat (ITR) were generated with Bal31 exonuclease and the resulting molecules constructed into plasmids which contained two inverted copies of the deleted ITR separated by the bacterial neomycin phosphotransferase gene. To determine the effect of the deletion in vivo plasmids cleaved to expose the adenovirus termini were co-transfected with adenovirus type 2 DNA into tissue culture cells. The replicative ability of the molecules bearing adenovirus termini was assayed by Southern blotting of extracted DNA which had been treated with DpnI, a restriction enzyme which cleaves only methylated and therefore unreplicated, input DNA. Molecules containing the terminal 45 bp of the viral genome were fully active whereas molecules containing only 36 bp were in-active in this assay. Therefore sequences required for DNA replication are contained entirely within the terminal 45 bp of the viral genome. Thus, both the previously described highly conserved region (nucleotides 9-18) and the binding site for the cellular nuclear factor I (nucleotides 19-48) are essential for adenovirus DNA replication in vivo.

Adenoviruses, Human↗