EXO1

..We show here that the Mre11 complex functions together with exonuclease 1 (Exo1) in activation of the Mec1 signaling pathway after DNA damage and replication block...

..Rap1 and Rif2 prevent telomere degradation by inhibiting MRX access to telomeres, which are also protected from the Exo1 nuclease by Yku...

..MRX) and Sae2 are implicated in the onset of 5'-strand resection, whereas Sgs1/Top3/Rmi1 with Dna2 and Exo1 are involved in extensive resection...

..Cdk1 activity is required to generate these single-stranded regions, and deleting the EXO1 nuclease partially suppresses ten1-ts growth defects...

..We found that exonuclease 1 (Exo1) is important in assuring accurate junction formation during NHEJ...

b>Exo1 is a nuclease involved in mismatch repair, DSB repair, stalled replication fork processing and in the DNA damage response triggered by dysfunctional telomeres...

..We show that Exo1 is unique among the repair genes tested because like Rad9 and Rad24 checkpoint proteins, Exo1 inhibits the growth ..

..We found that simultaneous inactivation of Sgs1, Exo1, and Rad9, three DNA damage response (DDR) proteins, is sufficient to allow cell division in the absence of Cdc13...

Previous work in budding yeast has indicated that telomeres are protected, at least in part, from the action of Exo1, which degrades the C-rich strand of partially uncapped telomeres...

..Here we demonstrate that the Exo1 exonuclease is an initiator of the recombination process that allows cells to escape senescence and become immortal ..

..the absence of end protection by Ku, the requirement for the MRX complex is bypassed and resection is executed by Exo1. In contrast, both the Exo1 and Sgs1 resection pathways contribute to DSB processing in the absence of Ku and Sae2 ..

..The results indeed show that both Exo1 and the Mre11/Rad50/Xrs2 complex are required for telomeric resection after Yku loss in non-dividing cells...

..Resection proceeds by two pathways dependent on Exo1 or the BLM homolog, Sgs1...

..No processing activity is detectable in sae2Delta sgs1Delta cells, while the Exo1 exonuclease contributes to telomere end processing and elongation in both sae2Delta and sgs1Delta cells, suggesting ..

..Consistent with this, deletion of EXO1, encoding a nuclease that contributes to single stranded DNA accumulation after telomere uncapping, improves growth ..

..but several factors have been implicated, including the Mre11 complex (Mre11-Rad50-Xrs2/NBS1), Sae2/CtIP/Ctp1 and Exo1. Here we demonstrate that yeast Exo1 nuclease and Sgs1 helicase function in alternative pathways for DSB processing...

..annealing between distant repeats while the remaining long-range resection activity depends on the exonuclease Exo1. In exo1Deltasgs1Delta double mutants, the MRX complex together with Sae2 nuclease generate, in a stepwise manner, ..

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..that the sensitivity of rad53 mutants to DNA-damaging agents can be almost completely suppressed by deletion of the EXO1 gene, which encodes an enigmatic flap endonuclease...

..DNA accumulation at the ends of DSBs, and this checkpoint function can be overcome by overproducing the exonuclease Exo1. Second, Tel1 can activate the checkpoint response to DSBs independently of Mec1, although its signalling activity ..

..Examining the genetic interaction of these two exo1 mutations with rad27Delta suggest that the Exo1p flap-endonuclease activity and not the dsDNA 5'-3' exonuclease is ..

..One gene was found to encode a homologue of Schizosaccharomyces pombe EXO1, a double-stranded DNA-specific 5'-3' exonuclease. S. cerevisiae EXO1 interacted with both S...

..Multiple copies of the EXO1 gene, encoding a 5' to 3' double-strand DNA exonuclease, were found to suppress the high MMS sensitivity of these ..

..In addition to the yeast MutS and MutL homologs, the exonuclease Exo1p and the nucleotide excision repair proteins Rad1p and Rad10p were found to have roles in inhibiting recombination between mismatched substrates...

..An allele, pol2-C1089Y, was identified in a screen of Polepsilon mutants that in combination with an exonuclease I (exo1) mutation could cause a synergistic increase in mutations within homonucleotide runs...

..Here, we reveal that in the absence of exonuclease Exo1 activity, deletion or mutation of the Saccharomyces cerevisiae RecQ-family helicase, Sgs1, causes pronounced ..

..Finally, our results show that much of the increase in spontaneous mutation observed in an exo1Delta strain is REV3-dependent, in turn suggesting that Exo1p is also involved in one or more MMR-independent mutation avoidance pathways...

..Mutation of EXO1, which encodes a 5' to 3' exonuclease, was found to increase the ionizing radiation sensitivity of both mre11Delta ..

..We propose that at least two separate activities associated with the N-terminus of Mre11p are required for its mitotic function...

..increasing levels of single-stranded DNA in subtelomeric Y' regions, and find that the mismatch repair-associated EXO1 gene is required for both ssDNA generation and cell cycle arrest of yku70Delta mutants...

..expressed cDNAs that suppress the DNA repair deficiency of rad50 mutants yielded multiple isolates of two genes: EXO1 and TLC1...

..technique (2D gel) and psoralen crosslinking combined with electron microscopy (EM), we found that the Exo1 exonuclease is recruited to stalled forks and, in rad53 mutants, counteracts reversed fork accumulation by ..

..Our results demonstrate that one major functional role that Est1 brings to the telomerase complex is the capping or protection of telomeres...

..The Mre11-Rad50-Xrs2 complex with Sae2 initiates resection, whereas two nucleases, Exo1 and Dna2, and the DNA helicase-topoisomerase complex Sgs1-Top3-Rmi1 generate longer ssDNA at DSBs...

The Rad2/XPG family nuclease, Exo1, functions in a variety of DNA repair pathways. During meiosis, Exo1 promotes crossover recombination and thereby facilitates chromosome segregation at the first division...

..In this study, we identified the site of yeast Mlh1 critical for the interaction with Exo1, Ntg2, and Sgs1 proteins, designated as site S2 by reference to the Mlh1/Pms1 heterodimerization site S1...

..Exonuclease 1 (Exo1) processes stalled replication forks in checkpoint-defective yeast cells...

..Analysis of strains with different mutant alleles of MRE11 (mre11-58S and mre11-H125N) and deleted for EXO1 indicated that these two nucleases make significant contributions to repair of VDE-DSBs...

..DSB in single cells, we found that nearly all DSBs are converted to CRBs in cells lacking both exonuclease 1 (EXO1) activity and MRX complex...

..We suggest that sumoylation of different domains of RecQ DNA helicases from different organisms contributes to conserved roles in regulating telomeric recombination...

..inverted repeat fusion, and that their activities are distinguishable by their interactions with exonuclease 1 (Exo1)...

..the telomere capping protein Cdc13 protects telomeres from the activity of the helicase Pif1 and the exonuclease Exo1. Our data support a two-stage model for the DDR at uncapped telomeres; Pif1 and Exo1 resect telomeric DNA <5 kb ..

b>Exo1 is a member of the Rad2 protein family and possesses both 5'-3' exonuclease and 5' flap endonuclease activities...

..We show that during repair of UV lesions in noncycling cells, Exo1-mediated processing of nucleotide excision repair (NER) intermediates competes with repair DNA synthesis...

..Therefore, the budding yeast 14-3-3 proteins contribute to the robustness of the two major mitotic checkpoints and, by doing so, may also ensure optimal coordination between the responses to two distinct types of damage...

..The mutator phenotype exhibited in mlh1-I296S strains was partially suppressed at 35 degrees by EXO1 overexpression...

..Therefore, we propose that the R/K-S-R/K-Y/F-Y/F sequence could define a Mhl1 binding motif. The results also suggest that base excision repair and MMR can cooperate to prevent deleterious effects of oxidative DNA damage...

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..Three members of the Saccharomyces cerevisiae Rad2 family, Rad2, Rad27, and exonuclease 1 (Exo1), exhibit both 5' exonuclease and flap endonuclease activities...

A plasmid gap repair assay was used to assess the role of three known nucleases, Exo1, Mre11 and Rad1, in the processing of DNA ends and resolution of recombination intermediates during double-strand gap repair...

..Mutation rates and spectra and synergistic interactions of the pol3-L523X mutations with msh2, exo1, and rad27/fen1 defects were indistinguishable from those observed with previously studied exonuclease-defective ..

..Here we establish a novel overlapping function for PSO2 with MutS mismatch repair factors and the 5'-3' exonuclease Exo1 in the repair of DNA ICLs, which is confined to S phase...

..proteins-Msh2, Mlh1, or Pms1-and severe sensitivity to PAA is observed in the absence of the core proteins Msh6 or Exo1, but not Msh3...

..However, the non-homologous end joining function of MRX complex does not appear to participate in the suppression of GCRs...

..In addition, trm2 exo1 double mutants were synergistically more sensitive to MMS and ionizing radiation than either of the single mutant ..

..inviability of two mutants, msh2-L560S pol3-01 and msh2-L910P pol3-01, was suppressed by overexpression of EXO1 and MSH6, respectively...

..b>EXO1 codes for a Rad2p family member nuclease that has been implicated in a multitude of eukaryotic DNA metabolic ..

..This analysis underscores the importance of functional characterization of missense alleles to ensure that they are the causative factor for disease...

..Moreover, we observed that while overexpression of the 5'-3' exonuclease gene EXO1 partially complements the MMS sensitivity of mre11, rad50, and xrs2 null mutants, it has no effect on telomere ..

..Our data thus provide in vivo evidence for the types of DNA lesions predicted to occur when lagging-strand synthesis is deficient and suggest that Dna2p and Rad27p collaborate in the processing of Okazaki fragments...

..We have genetically characterized the roles of the 5'-->3' Exo1 and the 3'-->5' DNA polymerase exonucleases in mismatch repair in the yeast Saccharomyces cerevisiae by using ..

b>EXO1 interacts with MSH2 and MLH1 and has been proposed to be a redundant exonuclease that functions in mismatch repair (MMR)...

..Mutation in EXO1 reduces gene conversion frequencies significantly at some but not all loci, suggesting that other enzymes are also ..

..These results provide a molecular explanation for the observed in vivo defects of the rad50 Walker mutant strains and reveal a novel ATP-independent function for Rad50 in DNA end-bridging...

..at the MAT locus by HO-endonuclease with higher sterility rate among the survivors compared to wild type (wt) or exo1 single mutants...

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..023), ERCC6 Q1413R (P = 0.025), POLE (P = 0.014) and base excision repair: APEX1 D148E (P = 0.028); EXO1 E670G (P = 0.007); POLB P242R (P = 0.018)...

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..function in homologous recombination and interstrand cross-link (ICL) repair pathways, respectively, while the Exo1 nuclease is involved in homologous recombination and mismatch repair...

..These data suggest that MSH2 and possibly other components of DNA mismatch repair exist in a complex with NER proteins, providing a biochemical and genetical basis for these proteins to function in common processes...

..The last aim includes in vitro studies to identify preferred DNA substrates for Rad55:Rad57 binding and stabilization of the Rad51 nucleoprotein by Rad55:Rad57 in the presence or absence of Srs2. ..

..Finally, we have shown high frequency RAD51-independent recombination of repeated sequences; genetic studies are proposed to identify components of the RAD51-independent recombination pathway. ..

..elegans and Xenopus will be featured. Much of the conference will be devoted to topics of concern both to the National Cancer Institute and to the Institute of Environmental and Health Sciences. ..

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..The last aim includes in vitro studies to identify preferred DNA substrates for Rad55:Rad57 binding and stabilization of the Rad51 nucleoprotein by Rad55:Rad57 in the presence or absence of Srs2. ..

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..Finally, we have shown high frequency R/AD57-independentrecombination of repeated sequences; genetic studies are proposed to identify components of the R/\D57-independent recombination pathway. ..

..of DNA ends: first the Mre11 complex and Sae2 remove short oligonucleotides from the 5'end, second, Exo1 or Sgs1 and Dna2 carry out extensive resection of the tailed intermediate...

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..In this proposal, genetic and physical approaches will be used to identify the genes that regulate chromosome rearrangements during BIR, and to define the mechanism for DNA synthesis used in BIR. ..

..The use of gene replacement for targeted gene disruption has application for gene therapy, thus an understanding of the mechanism is of fundamental importance. ..

..Other genes that function in the RAD51 -independent recombination pathway will be identified using the colony-color sectoring assay and by interaction of their products with Rad59 in a two hybrid screen ..

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..Finally, we plan to screen for hyperactive alleles of RAD51 that suppress the DNA repair defect of rad55/57 mutants. Characterization of such alleles may provide insight into the function of these proteins. ..

..Conserved residues in Mre11 predicted to be important for nuclease activity will be altered and tested for in vivo function, and the Mre11 protein complex will be purified to test the hypothesis that is a nuclease. ..

..Dr. Lundblad's laboratory in the Department of Molecular and Human Genetics at the Baylor College of Medicine provides an excellent environment in which to develop my scientific skills. ..

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