Previous experiments showed that a synchronous population of Tetrahymena could divide even though DNA replication was blocked during the latter half of the preceding S-period byaddition of methotrexate plus uridine (M + U). Furthermore, it was found that the DNA fraction which was in replication at the time of inhibition became localized in the cytoplasm following elimination from the nucleus a...

Three phosphatidylinositol-3-kinase-related protein kinases implement cellular responses to DNA damage. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and ataxia-telangiectasia mutated respond primarily to DNA double-strand breaks (DSBs). Ataxia-telangiectasia and RAD3-related (ATR) signals the accumulation of replication protein A (RPA)-covered single-stranded DNA (ssDNA), which is ...

A model is proposed of the way in which the unwinding of the chromosomal DNA loops is controlled during DNA replication. It is based on the observation of a permanent binding of replication origins to the nuclear matrix and of a transient attachment of replicating DNA regions to sites in the immediate neighbourhood. DNA unwinding is controlled while the replicating loops are reeled through the ...

Mutations in genes involved in DNA replication, such as flap endonuclease 1 (FEN1), can cause single-stranded DNA breaks (SSBs) and subsequent collapse of DNA replication forks leading to DNA replication stresses. Persistent replication stresses normally induce p53-mediated senescence or apoptosis to prevent tumour progression. It is unclear how some mutant cells can overcome persistent replica...

In all organisms from bacteria and archaea to eukarya, single-stranded DNA binding proteins play an essential role in most, if not all, nuclear metabolism involving single-stranded DNA (ssDNA). Replication protein A (RPA), the major eukaryotic ssDNA binding protein, has two important roles in DNA metabolism: (1) in binding ssDNA to protect it and to keep it unfolded, and (2) in coordinating the...

The mechanism of epigenetic inheritance following DNA replication may involve dissociation of chromosomal proteins from parental DNA and reassembly on daughter strands in a specific order. Here we investigated the behaviour of different types of chromosomal proteins using newly developed methods that allow assessment of the assembly of proteins during DNA replication. Unexpectedly, most chromat...

The microbicidal myeloperoxidase (MPO)-H2O2-chloride system strongly inhibits Escherichia coli DNA synthesis. Also, cell envelopes from MPO-treated E. coli cells lose their ability to interact with hemimethylated DNA sequences of oriC, the chromosomal origin of replication, raising the prospect that suppression of DNA synthesis involves impairment of oriC-related functions (H. Rosen, et al. Pro...

Chromatin assembly factor 1 (CAF-1) is required for inheritance of epigenetically determined chromosomal states in vivo and promotes assembly of chromatin during DNA replication in vitro. Herein, we demonstrate that after DNA replication, replicated, but not unreplicated, DNA is also competent for CAF-1-dependent chromatin assembly. The proliferating cell nuclear antigen (PCNA), a DNA polymeras...

In response to replication stress cells activate the intra-S checkpoint, induce DNA repair pathways, increase nucleotide levels, and inhibit origin firing. Here, we report that Rrm3 associates with a subset of replication origins and controls DNA synthesis during replication stress. The N-terminal domain required for control of DNA synthesis maps to residues 186-212 that are also critical for b...

DNA replication is one of the most important events in living cells, and it is still a key problem how the DNA replication machinery works in its details. A replication fork has to be a very dynamic apparatus since frequent DNA polymerase switches from the initiating DNA polymerase alpha to the processive elongating DNA polymerase delta occur at the leading strand (about 8 x 10(4) fold on both ...