• Journal of Microbiology and Biotechnology
• /
• v.25 no.10
• /
• pp.1768-1771
• /
• 2015

Human Fen1 protein (hFen1) plays an important role in Okazaki fragment processing by cleaving the flap structure at the junction between single-stranded (ss) DNA and doublestranded (ds) DNA, an intermediate formed during Okazaki fragment processing, resulting in ligatable nicked dsDNA. It was reported that hChlR1, a member of the cohesion establishment factor family, stimulates hFen1 nuclease activity regardless of its ATPase activity. In this study, we found that cohesion establishment factors cooperatively stimulate endonuclease activity of hFen1 in in vivo mimic condition, including replication protein-A-coated DNA and high salt. Our findings are helpful to explain how a DNA replication machinery larger than the cohesion complex goes through the cohesin ring structure on DNA during S phase in the cell cycle.

• Journal of Radiation Industry
• /
• v.10 no.4
• /
• pp.243-248
• /
• 2016

Argonaute 2 (AtAGO2) is a well characterized effector protein in Arabidopsis for its functionalities associated with DNA double-strand break (DSB)-induced small RNAs (diRNAs) and for its inducible expression upon ${\gamma}$-irradiation. However, its transcriptional regulation depending on the recovery time after the irradiation and on the specific response to DSBs has been poorly understood. We analyzed the 1,313 bp promoter sequence of the AtAGO2 gene ($1.3kb_{pro}$) to characterize the transcriptional regulation of AtAGO2 at various recovery times after ${\gamma}$-irradiation. A stable transformant harboring $1.3kb_{pro}$ fused with GUS gene showed that the AtAGO2 is highly expressed in response to ${\gamma}$-irradiation, after which the expression of the gene is gradually decreased until 5 days of DNA damage recovery. We also confirm that the AtAGO2 expression patterns are similar to that of ${\gamma}$-irradiation after the treatments of radiomimetic genotoxins (bleomycin and zeocin). However, methyl methanesulfonate and mitomycin C, which are associated with the inhibition of DNA replication, do not induce the expression of the AtAGO2, suggesting that the expression of the AtAGO2 is closely related with DNA DSBs rather than DNA replication.

• BMB Reports
• /
• v.41 no.11
• /
• pp.778-783
• /
• 2008

Turnip yellow mosaic virus (TYMV) RNA has two hairpins in its 5' untranslated region (5'-UTR). To investigate the role of the hairpins in replication of TYMV, mutants lacking one or both of the two hairpins were constructed. The TYMV constructs were introduced into Chinese cabbage by an Agrobacterium-mediated T-DNA transfer method, called agroinfiltration. Analysis of total RNA from agroinfiltrated leaves showed that replication of the mutant TYMV RNA lacking both hairpins was about 1/100 of wild type. This mutant was also impaired in systemic spread. Deletion analysis of each hairpin revealed that both hairpins were needed for maximal replication. The deletion analysis along with sequence modification of the hairpin structure indicates that the second hairpin plays a role in efficient long-distance systemic movement of TYMV.

• BMB Reports
• /
• v.29 no.1
• /
• pp.63-67
• /
• 1996

In order to elucidate the molecular mechanism of plasmid incompatibility of broad host-range plasmid R1162, the plasmid-encoded replication protein RepIB was purified and tested for binding to the 20 bp direct repeat (DR) DNA sequence which is reiterated 3 and 1/2 times within the replicative origin of the plasmid. The RepIB protein specifically binds to the DR DNA. Point mutations in the DR which affect expression of plasmid incompatibility also coordinately affect binding. These results indicate that the incompatibility of broad host-range plasmid R1162 is exerted by the DR DNA by titrating the essential replication protein RepIB.

• Journal of Life Science
• /
• v.10 no.6
• /
• pp.610-616
• /
• 2000

The DPB11 gene, which genetically interacts with DNA polymerase II ($\varepsilon$) encoded by POL2 and DPB2, is required for DNA replication and the S phase checkpoint in Saccharomyces cerevusiae. The transcripts of DPB11 did not fluctuated as evidently as DPB2 and POL2 genes during cell cycle. To identify the physical interaction between Dpb2 and Dpb11, we examined the interaction by two-hybrid system. The interaction between Dpb2 and Dpb11 was detected in a two-hybrid assay. These results suggest that the amount of the Dpb2-Dpb11 complex may peak at the G1/S boundary. Therefore, we strongly suggest the involvement of the Dpb2-Dpb11 complex in a progression of DNA replication and S-phase checkpoint.

• BMB Reports
• /
• v.50 no.7
• /
• pp.379-383
• /
• 2017

We previously reported that p53 plays a role as a key regulator in the tetraploid G1 checkpoint, which is activated by actin damage-induced cytokinesis blockade and then prevents uncoupled DNA replication and nuclear division without cytokinesis. In this study, we investigated a role of Skp2, which targets CDK2 inhibitor p27/Kip1, in actin damage-induced tetraploid G1 arrest. Expression of Skp2 was reduced, but p27/Kip1 was increased, after actin damage-induced cytokinesis blockade. The role of Skp2 repression in tetraploid G1 arrest was investigated by analyzing the effects of ectopic expression of Skp2. After actin damage, ectopic expression of Skp2 resulted in DNA synthesis and accumulation of multinucleated cells, and ultimately, induction of apoptosis. These results suggest that Skp2 repression is important for sustaining tetraploid G1 arrest after cytokinesis blockade and is required to prevent uncoupled DNA replication and nuclear division without cytokinesis.

• The Korean Journal of Pharmacology
• /
• v.28 no.2
• /
• pp.213-222
• /
• 1992

We investigated effects of several chemical carcinogens, i.e., $benzo({\alpha})pyrene$ (BP),7,12-dimethylbenz(a)anthracene (DMBA), nitrosomethyl urea (NMU), and nicotine on the replication, cytolyticity, DNA synthesis, and protein synthesis of type 1 herpes simplex virus (HSV-1) in viral infected Vero cell monolayers. We observed that the BP and DMBA did not show such activity. All chemical carcinogens did not inhibit the synthesis of viral DNA, but the expression of gamma viral proteins that are expressed from the newly synthesized progeny viral DNA was somewhat notably inhibited by BP and DMBA. However, the synthesis of alpha and beta viral proteins was not altered by the chemical carcinogens. These data indicate that the gamma viral proteins expressed from the newly synthesized DNA in the presence of chemical carcinogens in the culture medium may be defective. This is further supported by the fact that the virus fail to replicate in the presence of these chemical carcinogens, in spite of viral DNA and proteins are somewhat normally synthesized.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.4
• /
• pp.637-647
• /
• 2016

Proliferating cell nuclear antigen (PCNA) is a critical eukaryotic replication accessory factor that supports DNA binding in DNA processing, such as DNA replication, repair, and recombination. PCNA consists of three toroidal-shaped monomers that encircle double-stranded DNA. The diverse functions of PCNA may be regulated by its interactions with partner proteins. Many of the PCNA partner proteins generally have a conserved PCNA-interacting peptide (PIP) motif, located at the N- or C- terminal region. The PIP motif forms a 3₁₀ helix that enters into the hydrophobic groove produced by an interdomain-connecting loop, a central loop, and a C-terminal tail in the PCNA. Post-translational modification of PCNA also plays a critical role in regulation of its function and binding partner proteins. Structural and biochemical studies of PCNA-protein will be useful in designing therapeutic agents, as well as estimating the outcome of anticancer drug development. This review summarizes the characterization of eukaryotic PCNA in relation to the protein structures, functions, and modifications, and interaction with proteins.

• Molecular & Cellular Toxicology
• /
• v.3 no.sup4
• /
• pp.35.2-35.2
• /
• 2007

• Proceedings of the SCSK Conference
• /
• 2003.09b
• /
• pp.405-406
• /
• 2003

DNA is known as the genetic material in cells. Various environmental factors can cause DNA damages. One of them is sunlight. The life on earth depends on the sunlight, but on the other hand, the UV light in sunlight can cause skin DNA damages. When these damages are not fully repaired before replication, they can lead to mutations of oncogenes and tumour suppressor gene and result in photo carcinogenesis, in the end, skin cancer.(omitted)