endodeoxyribonucleases

..We observe comparably high frequencies in human T cells, raising the possibility of strategies based on zinc-finger nucleases for the treatment of disease...

..marcescens nuclease structure, the functional characteristics of the natural and mutational forms of the enzyme and consideration of its structural analogy with homing endo-nuclease I-PpoI...

..The use of tailored HEs opens up new possibilities for gene therapy in patients with monogenic diseases that can be treated ex vivo. This review provides an overview of recent advances in this field...

..Taken together with previous observations on NER-deficient M. tuberculosis, these results suggest that NER is an important DNA repair pathway in mycobacteria...

..Neither of these upstream genes, nor the downstream gene, are essential for either cell viability or transformability...

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..Systematic application of this approach should produce a global map of gene function...

..We suggest that Top3-Rmi1 and MRX are important for recruitment of the Sgs1-Dna2 complex to DSBs. Our experiments provide a mechanistic framework for understanding the initial steps of recombinational DNA repair in eukaryotes...

..The Fpg protein also excised FapyGua and 8-OH-Gua from visible light/MB-treated DNA. The presence of these products in the supernatant fractions confirmed their excision.(ABSTRACT TRUNCATED AT 250 WORDS)..

..Our findings suggest a general mechanism for repair of protein-linked DSBs...

..Our results suggest that CRN-1/FEN-1 may play a critical role in switching the state of cells from DNA replication/repair to DNA degradation during apoptosis...

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..The structure indicates that the two active sites of EndoG occupy the most remote spatial position possible at the molecular surface and a concerted substrate processing is unlikely...

..Finally, harnessing the cellular HR pathway through Rep-mediated nicking expands the range of strategies that make use of AAV elements to bring about stable genetic modification of human cells...

..Our results establish a novel functional role for MBD4 in the cellular response to DNA damage and may have implications for its role in suppressing neoplasia...

..The gp16 regulator is essential to coordinate the gp17 motor ATPase, translocase, and nuclease activities, otherwise it could be suicidal to the virus...

..Oligonucleotide cleavage assay results suggest the essential function of the three-base interaction may be to position the scissile phosphate for cleavage, rather than to directly contribute to binding affinity...

..Our results also demonstrate that overexpression of the nuclease in edelfosine-treated promastigotes causes a significant increase in the percentage of TUNEL-positive parasites...

..These observations suggest that the conserved role of the MRN complex in these meiotic functions is independent of Rec12(Spo11) removal...

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..We propose that the Penelope EN cleaves the target DNA during transposition, generating a primer for reverse transcription. Our results show that an active Uri EN has been adopted by a retrotransposon...

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..The comparison highlights the versatility of Holliday junction resolution, and extracts some general principles of recognition...

..Our data thus provide in vivo evidence for an essential function of FEN1 in DNA repair, as well as in DNA replication...

..The mus81 meiotic defect is rescued by expression of a bacterial Holliday junction resolvase. These findings constitute strong evidence that Mus81 and Eme1 are subunits of a nuclear Holliday junction resolvase...

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..The purified K166G mutant showed a loss of gp17-ATPase activity. The data, for the first time, implicated a specific ATPase center in the viral dsDNA packaging...

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..Collectively, these results suggest that BRCA1 may function as a coordinator of multiple activities required for maintenance of genomic integrity during the process of DNA replication and point to a central role for BRCA1 in DNA repair...

..Since the catalytic motifs of the N-terminal ATPase are highly conserved among >200 large terminase sequences analyzed, these may represent common themes in phage and herpes viral DNA translocation...

..We propose that the novel substrate specificities of Nfo and Apn1 play an important role in counteracting oxidative DNA base damage...

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..Although the DNA recognition mechanisms may be distinct, it appears that T4 and other phage terminases employ a common catalytic paradigm for phosphodiester bond cleavage that is used by numerous nucleases...

..We have also obtained evidence suggesting that the enzyme acts by the same mechanism on PydC photoproducts which are thought to be of primary importance in UV-induced mutagenesis...

..The data demonstrate that MBD2 and MBD4 bind specifically to methyl-CpG in vitro and in vivo and are therefore likely to be mediators of the biological consequences of the methylation signal...

..However, Mre11 nuclease activity is essential for resection in the absence of extensive resection enzymes. The results provide new insights into how MRX catalyses end resection and recombination initiation...

..We further show that sgs1Delta mre11-H125N, but not sgs1Delta, is very sensitive to IR, implicating the Sgs1 helicase in the Dna2-mediated pathway...

..We suggest that escape from the DNA damage-induced G2/M checkpoint depends on the extent of ssDNA created at broken chromosome ends. RPA appears to play a key intermediate step in this adaptation...

..7 A, b = 74.5 A, c = 68.9 A, and diffract to beyond 2 A. Low-resolution native data sets have been recorded and a search is under way for heavy-atom derivatives...

..003%. This system should also be readily applicable for directed evolution of other DNA cleavage enzymes...

..Because FEN-1 is an essential enzyme that plays its roles in DNA repair and DNA replication, DSBs may be produced in cells as by-products of the activity of FEN-1...

..The combination of a compact core and a flexible outer layer could be related to the structural requirements of DNA-protein binding...

..The method can find applications in sensitive and specific detection of viral duplex DNA...

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..These biochemical properties suggest that deoxyinosine 3'-endonuclease might be important in the repair of IDM structures generated in lagging strand during DNA replication...

..The implications of these results with respect to the two roles of the terminase holoenzyme, DNA maturation and DNA packaging, are discussed...

..These results suggest that Mre11 (with Sae2) and Slx4 represent two new structure-specific endonucleases that protect cells from trapped topoisomerase by removing topoisomerase-DNA adducts...

..Our data also suggest that early prophase barriers to utilization of sister chromatids as repair templates do not depend on central region assembly...

..Deletion of NUC1 diminishes apoptotic death when mitochondrial respiration is increased but enhances necrotic death when oxidative phosphorylation is repressed, pointing to dual--lethal and vital--roles for EndoG...

..A caspase-activated DNase performs DNA degradation in caspase-dependent apoptosis, but other endonucleases like L-DNase II or GAAD are activated in caspase-independent apoptosis, allowing the complete dismantling of the cell...

..Recent studies imply the involvement of several mitochondrial proteins, including endonuclease G (EndoG) and Bcl-2/adenovirus E1B 19 kDa-interacting protein (BNIP3), in the pathway of non-neuronal cells...

..We have recently demonstrated that epidermal keratinocytes strongly express DNase1-like 2 (DNase1L2) in a differentiation-associated manner...

..Emission fluorescence suggested that the three Trp residues of MobM are located within a hydrophobic environment. A molecular model of MobM on the known structure of colicin Ia has been built...

..Loss of activity in the DH1-1A endonuclease and target site provides one explanation for co-existence of the intein(+) and intein(-) alleles...

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..Since no differences were found between the open reading frame sequences of these alleles, it is likely that the A-75G transition causes the allelic difference in the promoter activity of the gene, underlying the genetic polymorphism...

..These results demonstrate essential but separable roles for NHEJ pathway genes in the repair of chromosomal DSBs that are structurally similar to those occurring during cellular development...

..This selection system may facilitate the study of sequence-specific DNA cleaving enzymes, and selections based on this work may enable the evolution of homing endonucleases with novel activities or specificities...

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..Instead, we find that Rad50 inhibits ssDNA accumulation and promotes cdc13-1 cell viability, consistent with a major role for MRX in telomere capping...

..The recruitment of DNA repair-related proteins to the telomeres at particular times in the cell cycle suggests that the normal terminus of a chromosome is recognized as a DSB during the course of replication...

..Only after specific binding of the UvrB dimer to a damaged site and subsequent release of UvrA is the contact between the domain 4 regions broken, allowing recruitment of UvrC and subsequent incisions...

..Together, these results demonstrate that the DNA repair machinery distinguishes between different types of damage in G1, which translates into different modes of checkpoint activation in G1 and S/G2 cells...

..A model that summarizes our present and puzzling data on the origin and repair of endogenous AP sites is also presented...

..Thus, MRX may regulate two pathways of chromatin changes: nucleosome displacement for efficient recruitment of homologous recombination proteins; and phosphorylation of H2A, which modulates checkpoint responses to DNA damage...

..The interaction of Rsc1p with Mre11p appears to be vital for survival from genotoxic stress. These results suggest that chromatin remodeling by RSC is important for NHEJ...

..BIR is also elevated in rad51 mutants, but yku70Delta did not suppress BIR in a rad51 background. These results indicate that Mre11 functions in Rad51-independent BIR, and that Ku functions in Rad51-dependent BIR...

..These data indicate, at least in budding yeast, that alternate pathways enforce replication slowing depending on the particular DNA lesion...

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..These results suggest that the MRX complex is essential for joining of incompatible ends by NHEJ, and the ATP-dependent activities of Rad50 are critical for this process...

..Sequence identities of 1-5 base pairs are present at all of these junctions, and their diversity is consistent with the products of nonhomologous end-joining observed in vivo...

..These results identify a novel role in yeast NHEJ for the poorly characterized Ku80 C-terminal and Xrs2 FHA domains, and they suggest that redundant binding of DNA ligase IV facilitates completion of this DNA repair event...

..This result suggests that the total amount of Xrs2 protein is a critical determinant for the function of the MRX complex especially with regard to telomere maintenance and meiotic DSB formation...

..We would predict that the HAP1 protein is important in human cells for protection against the toxic and mutagenic effects of DNA damaging agents...

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..Similarities and differences between NHEJ repair in yeast and mammalian cells are discussed...

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..Genetic analyses demonstrate that the complex events are dependent on the Pol zeta translesion polymerase, thus implicating the DNA damage bypass activity of low-fidelity translesion polymerases in hypermutation phenomena...

..Additionally, an aberrant transcript without genomic mutation was found in a breast tumor. These findings suggest an occasional role for MRE11 alterations in the development of primary tumors...

..In doing so, Ku helps to avoid the formation of the intermediary free double strand breaks, possibly helping to reduce the mutagenic event that might result from the misjoining of frank double strand breaks...

..This study suggests a novel link between transcription factor regulation, oxidative signalling and DNA repair processes in higher eukaryotes...

..These results support models in which RecG acts at a replication fork stalled at a lesion in the DNA, catalysing fork regression and forming a Holliday junction that can then be acted upon by Hjc...

..We also demonstrate that Mre11 binds as a dimer between the catalytic domains of Rad50, bringing the nuclease activities of Mre11 in close proximity to the ATPase and DNA binding activities of Rad50...

..Thus, the integrity of the Mre11/Rad50/Xrs2 complex is specifically required for checkpoint activation after the formation of DSBs...

..Taken together, these results demonstrate a clear role for the lesion-specific enzyme, Tpp1, in the repair of a subset of DNA strand breaks...

..Therefore, this large inhibition of the excision of DHT by the presence of an opposite AP site may minimize the formation of double-strand breaks in the processing of DNA clustered damages...

..Genetic analysis of these mutants suggested that at least three distinct pathways can suppress GCRs: two that suppress microhomology-mediated GCRs (RFA1 and RAD27) and one that suppresses non-homology-mediated GCRs (RAD50/MRE11/XRS2)...

..Together, these results support and extend a current model regarding Mre11 structure and functions in mitosis and meiosis...

..Using a two-hybrid system, we found that Mre11 interacts with Rad50 and itself in vivo. These results suggest that Mre11 and Rad50 proteins work in a complex in DSB formation and DNA repair during vegetative growth...

..Thus, the processivity subunit of the holoenzyme is not required for type II UV mutagenesis, in agreement with a mechanism involving filling-in of short single-stranded DNA gaps...

..The extent of excision is therefore controlled by one or more components of the repair system...

..This second repair pathway involves the products of the rhp51 gene (the homolog of the RAD51 gene of S. cerevisiae) and the rad2 gene...

..The MRE11 locus maps to human chromosome 11q21 in a region frequently associated with cancer-related chromosomal abnormalities. A MRE11-related locus was found on chromosome 7q11.2-q11.3...

..These findings indicate that the function of the RAD52 epistasis group is conserved in human cells...

..The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination...

..S. cerevisiae NTG1 does not have the [4Fe-4S] cluster DNA binding domain characteristic of the other members of this family...

..Surprisingly, a high basal level of DIN7 expression was found in strains in which the DUN1 gene was inactivated by transposon insertion. We suggest that a form of Dun1 may be a negative regulator of the DIN7 gene expression...

..This will allow the comparison of representative examples of the two classes of enzymes that, although otherwise unrelated, carry out the same biological function. ..

..The results of the proposed study should provide insight into the suitability of PARP-1 as a novel target for the treatment of allergen-induced respiratory diseases such as asthma. ..

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..Applications to human health include defining the causes of individual variation in radiosensitivity and the development of mechanistic models for risk estimation of cancer etiology by low dose and low dose rate exposures. ..

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..Applications to human health include defining the causes of individual variation in radiosensitivity and the development of mechanistic models for risk estimation of cancer etiology by low dose and low dose rate exposures. ..

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..If increases in mutation frequency drive tumor progression, it is extremely important to identify agents that can inhibit mutagenesis and thereby prevent or impede the progression of human cancers. ..

..Also, potential regulatory pathways and molecules involved in control of muscle size will be determined. ..

..Further, this system will be used to study the roles played by various DNA repair enzymes, DNA polymerases and accessory proteins in shaping the strand bias and spectrum of mutations responsible for antibody maturation. ..

..This work will create the tools necessary for the monitoring of tumor cells in live animals when they are treated with PB as part of combination chemotherapy. ..

..cerevisiae. As a consequence, it is anticipated that these studies will provide genetic and biochemical insights that can be applied to the study of the genetics of human cancer susceptibility. ..

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..Fifth, we search for enzymatic activities in extracts that carry out the cleavage step in class switch recombination. ..

..Furthermore, the application of the knowledge gleaned from this research provides the starting point for potentially new therapeutics and research tools. ..

..These studies may impact upon other genetic disorders as well, and upon cancer patients with low levels of ATM protein. ..

..d) Development of dynamic models of the DNA packaging process from the above data and the testing of these models...

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..This application will identify and characterize damage- surveillance and other mechanisms that suppress chromosome translocation to understand the defects in blood cancers and develop novel preventive and/or therapeutic strategies. ..

..Furthermore, since DSB repair by NHEJ is remarkably conserved from yeast to humans, these studies will help to dissect the similar pathways in humans. ..

..Some of the principles gleaned from this study will have implications in global symbiotic or commensalist relationships among host-parasite genomes. ..

..The experiments in this proposal are aimed at understanding the processes of mutagenesis and repair of mitochondrial DNA in yeast, however, these studies may lead to insights into similar processes in human mitochondrial DNA. ..

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..The information gleaned from the proposal will also provide a logical framework as to how cells tolerate cancer therapeutic agent-induced DNA lesions and shed lights on the prevention and improved therapeutic intervention of cancers. ..

..Since the components of DSB repair are conserved from yeast to humans, the insights garnered from our research will be valuable for dissecting the equivalent process in human cells and will be of relevance to public health. ..

..Some of the principles gleaned from this study will have implications in global symbiotic or commensalist relationships among host-parasite genomes. ..

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..These insights will lead to new tools for cancer diagnostics as well as insights for use in improving the efficacy of known chemotherapeutic agents as well as for use in the development of new therapeutic approaches. ..

..These studies are directed at understanding how packaging protein interactions with DNA account for the major reconfiguring of packaging proteins that occurs during DNA packaging. ..

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