Dna repair

Colorectal cancer (CRC) is one of the most common malignant cancers of the colon worldwide. Several novel approaches to cancer treatment have emerged, including gene therapy, targeted therapy, and adjuvant therapies.

7p viharuno 03-01-2025 3 2   Download

Chương này trình bày về sự nhân đôi và sửa chữa của DNA (DNA replication and repair). Nội dung chính trong chương gồm có: các base (purine và pyrimidine), cấu trúc nucleosome, vai trò của histone, sự nhân đôi NST và DNA diễn ra ở pha S, phức hợp protein tại ngã ba nhân đôi, Đặc điểm của các DNA polymerases,… Mời các bạn cùng tham khảo.

50p tieu_vu16 03-01-2019 51 3   Download

Tyrosyl-DNA phosphodiesterase (TDP) cleaves the phosphodiester bond linking the active site tyrosine residue of topoisomerase I with the 3¢ terminus of DNA in topoisomerase I–DNA complexes which accumulate during treatment of cancer with camptothecin. In yeast, TDP mutation confers a 1000-fold hypersensitivity to camptothecin in the presence of an additional mutation of RAD9 gene [Pouliot, J.J., Yao, K.C., Robertson, C.A. & Nash, H.A. (1999) Science 286, 552–555].

8p research12 01-06-2013 42 3   Download

We report the cloning and functional charaterization of the full-length cDNA and gene encoding a Toxoplasma gondii DNA repair enzyme designated TgDRE. The gene is composed of three exons separated by two introns of 780 and 630 bp, and encodes a protein with a predicted molecular mass of 49.6 kDa. The native TgDRE protein, with a molecular mass of 60 kDa, is only detected in the virulent tachyzoite stage of T. gondii. However, the transcript is present in both asexual parasite stages, virulent tachyzoite and avirulent encysted bradyzoite. ...

9p research12 01-06-2013 37 5   Download

Chromatin is a highly dynamic structure that plays an essential role in regulating all nuclear processes that utilize the DNA template including DNA repair, replication, transcription and recombination. Thus, the mechanisms by which chromatin structures are assembled and modified are questions of broad interest. This minireview will focus on two groups of proteins: (a) histone chaperones and (b) ATPdependent chromatin remodeling machines, that co-operate to assemble DNA and histone proteins into chromatin....

7p research12 01-06-2013 36 4   Download

The organization of DNA within eukaryotic cell nuclei poses special problems and opportunities for the cell. For example, assembly of DNA into chromatin is thought to be a principle mechanism by which adventitious general transcription is repressed. However, access to genomic DNA for events such as DNA repair must be facilitated by energy-intensive processes that either directly alter chromatin structure or impart post-translational modifications, leading to increased DNA accessibility.

6p research12 01-06-2013 36 4   Download

The RuvA, RuvB andRuvCproteins ofEscherichia coliact together to process Holliday junctions formed during recombination and DNA repair. RuvA has a well-de®ned DNA binding surface that is sculptured speci®cally to accommodate a Holliday junction and allow subsequent loading of RuvB and RuvC. A negatively charged pin pro-jecting from the centre limits binding of linear duplexDNA. The amino-acid sequences forming the pin are highly con-served.

9p research12 29-04-2013 42 4   Download

DNA ligases are the enzymes responsible for the repair of single-strandedanddouble-strandednicks indsDNA.DNA ligases are structurally similar, possibly sharing a common molecular mechanism of nick recognition and ligation catalysis. This mechanism remains unclear, in part because the structure of ligase in complex with dsDNAhas yet to be solved.DNA ligases share common structural elementswith DNA polymerases, which have been cocrystallized with dsDNA. Based on the observed DNA polymerase–dsDNA interactions, we propose a mechanism for recognition of a single-stranded nick by DNA ligase....

7p tumor12 22-04-2013 42 2   Download

The RuvABC resolvasome ofEscherichia colicatalyses the resolution of Holliday junctions that arise during genetic recombination and DNA repair. This process involves two key steps: branch migration, catalysed by the RuvB protein that is targeted to the Holliday junction by the structure specific RuvAprotein, and resolution, which is catalysed by the RuvC endonuclease.

10p tumor12 22-04-2013 35 2   Download

Cryptochromes are blue-light photoreceptors sharing sequence similarity to photolyases, a class of flavoenzymes catalyzing repair ofUV-damagedDNAvia electron transfer mechanisms. Despite significant amino acid sequence simi-larity in both catalytic and cofactor-binding domains, cryptochromes lack DNA repair functions associated with photolyases, and the molecular mechanism involved in cryptochrome signaling remains obscure.

8p tumor12 20-04-2013 38 3   Download

Formamidopyrimidine-DNA glycosylase (Fpg protein) of Escherichia coliis a DNA repair enzyme that excises oxi-dized purine bases, most notably the mutagenic 7-hydro-8-oxoguanine, from damaged DNA. In order to identify specific contacts between nucleobases of DNA and amino acids from theE. coliFpg protein, photochemical cross-linking was employed using new reactive DNA duplexes containing 5-[4-[3-(trifluoromethyl)-3H-diazirin-3-yl]phe-nyl]-2¢-deoxyuridine dU* residues near the 7-hydro-8-oxoguanosine (oxoG) lesion. ...

5p fptmusic 16-04-2013 32 3   Download

One of the most drastic post-translational modification of proteins in eu-karyotic cells is poly(ADP-ribosyl)ation, catalysed by a family enzymes termed poly(ADP-ribose) polymerases (PARPs). In the human genome, 18 different genes have been identified that all encode PARP family members.

14p fptmusic 11-04-2013 53 2   Download

We have previously reported that sulfoquinovosylmonoacylglycerol (SQMG) is a potent inhibitor of mammalian DNA polymerases. DNA polymeraseb(pol b) is one of the most important enzymes protecting the cell against DNA damage by base excision repair. In this study, we charac-terized the inhibitory action of SQMG against rat pol b. SQMG competed with both the substrate and the template-primer for binding to polb.

13p fptmusic 11-04-2013 42 2   Download

Cockayne syndrome (CS) is a rare inherited human genetic disorder char-acterized by developmental abnormalities, UV sensitivity, and premature aging. The CS group B (CSB) protein belongs to the SNF2-family of DNA-dependent ATPases and is implicated in transcription elongation, transcription coupled repair, and base excision repair. It is a DNA stimula-ted ATPase and remodels chromatin in vitro. We demonstrate for the first time that full-length CSB positively cooperates in ATP hydrolysis as a function of protein concentration....

9p fptmusic 11-04-2013 41 2   Download

Histones are modified post-translationally, e.g. by methylation of lysine and arginine residues, and by phosphorylation of serine residues. These modifications regulate processes such as gene expression, DNA repair, and mitosis and meiosis. Recently, evidence has been provided that histones are also modified by covalent binding of the vitamin biotin.

11p fptmusic 11-04-2013 40 2   Download

DNA repair must take place within the context of chromatin, and it is therefore not surprising that many aspects of both chromatin components and proteins that modify chromatin have been implicated in this process. One of the best-characterized chromatin modification events in DNA-dam-age responses is the phosphorylation of the SQ motif found in histone H2A or the H2AX histone variant in higher eukaryotes. This modification is an early response to the induction of DNA damage, and occurs in a wide range of eukaryotic organisms, suggesting an important conserved func-tion....

10p fptmusic 11-04-2013 27 2   Download

Replication protein A (RPA), a heterotrimeric protein composed of 70, 32 and 14-kDa subunits, has been shown to be essential for DNA replication, repair, recombination, and transcription. Previously, we found that, in two seed plants, rice and Arabidopsis, there are two different types of RPA70-kDa subunit. Substantial biochemical and genetic characterization of these two subunits, termed OsRPA70aand OsRPA70bor AtRPA70a and AtRPA70b, respectively, is described in this report.

12p fptmusic 11-04-2013 43 3   Download

Human cells contain two homologs of the yeast RAD23 protein, hHR23A and hHR23B, which participate in the DNA repair process. hHR23B hou-ses a domain (residues 277–332, called XPCB) that binds specifically and directly to the xeroderma pigmentosum group C protein (XPC) to initiate nucleotide excision repair (NER). This domain shares sequence homology with a heat shock chaperonin-binding motif that is also found in the stress-inducible yeast phosphoprotein STI1.

10p awards 06-04-2013 35 3   Download

Base excision repair (BER), a major pathway for the removal of simple lesions in DNA, requires the co-ordinated action of several repair and ancillary proteins, the impairment of which can lead to genetic instability. We here address the role of poly(ADP-ribose) polymerase-1 (PARP-1) in BER. Using anin vitro cross-linking assay, we reveal that PARP-1 is always involved in repair of a uracil-containing oligonucleotide and that it binds to the damaged DNA during the early stages of repair.

0p awards 06-04-2013 44 2   Download

As an essential element, selenium is present in enzymes from several families, including glutathione peroxidases, and is thought to exert anticarcinogenic properties. A remarkable feature of selenium consists of its ability to oxidize thiols under reducing conditions. Thus, one mode of action recently suggested is the oxidation of thiol groups of metal-lothionein, thereby providing zinc for essential reactions.

10p awards 05-04-2013 47 3   Download