Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In mammalian cells, the Ku heterodimer is involved in DNA double-strand-break recognition and repair. We have established in yeast a connection between Ku activity and DNA double-strand-break damage repair, and a connection between Ku activity and commitment to DNA replication. We generated double-stranded DNA breaks in yeast cells in vivo by expressing a restriction endonuclease and have shown that yeast mutants lacking Ku p70 activity died while isogenic wild-type cells did not. Moreover, we have discovered that DNA damage occurs spontaneously during normal yeast mitotic growth, and that Ku functions in repair of this damage. We also observed that mitotically growing Ku p70 mutants have an anomalously high DNA content, suggesting a role for Ku in regulation of DNA synthesis. Finally, we present evidence that Ku p70 function is conserved between yeast, Drosophila, and humans.
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PMID:DNA double-strand-break sensitivity, DNA replication, and cell cycle arrest phenotypes of Ku-deficient Saccharomyces cerevisiae. 902 48

The Mre11/Rad50 complex is a critical component of the cellular response to DNA double-strand breaks, in organisms ranging from archaebacteria to humans. In mammalian cells, Mre11/Rad50 (M/R) associates with a third component, Nbs1, that regulates its activities and is targeted by signaling pathways that initiate DNA damage-induced checkpoint responses. Mutations in the genes that encode Nbs1 and Mre11 are responsible for the human radiation sensitivity disorders Nijmegen breakage syndrome (NBS) and ataxia-telangiectasia-like disorder (ATLD), respectively, which are characterized by defective checkpoint responses and high levels of chromosomal abnormalities. Here we demonstrate nucleotide-dependent DNA binding by the human M/R complex that requires the Nbs1 protein and is specific for double-strand DNA duplexes. Efficient DNA binding is only observed with non-hydrolyzable analogs of ATP, suggesting that ATP hydrolysis normally effects DNA release. The alleles of MRE11 associated with ATLD and the C-terminal Nbs1 polypeptide associated with NBS were expressed with the other components and found to form triple complexes except in the case of ATLD 3/4, which exhibits variability in Nbs1 association. The ATLD 1/2, ATLD 3/4, and p70 M/R/N complexes exhibit nucleotide-dependent DNA binding and exonuclease activity equivalent to the wild-type enzyme, although the ATLD complexes both show reduced activity in endonuclease assays. Sedimentation equilibrium analysis of the recombinant human complexes indicates that Mre11 is a stable dimer, Mre11 and Nbs1 form a 1:1 complex, and both M/R and M/R/N form large multimeric assemblies of approximately 1.2 MDa. Models of M/R/N stoichiometry in light of this and previous data are discussed.
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PMID:Regulation of Mre11/Rad50 by Nbs1: effects on nucleotide-dependent DNA binding and association with ataxia-telangiectasia-like disorder mutant complexes. 1296 88

Nucleotide excision repair (NER) is a very important defense system against various types of DNA damage, and it is necessary for maintaining genomic stability. The molecular mechanism of NER has been studied in considerable detail, and it has been shown that proper protein-protein interactions among NER factors are critical for efficient repair. A structure-specific endonuclease, XPF-ERCC1, which makes the 5' incision in NER, was shown to interact with a single-stranded DNA binding protein, RPA. However, the biological significance of this interaction was not studied in detail. We used the yeast two-hybrid assay to determine that XPF interacts with the p70 subunit of RPA. To further examine the role of this XPF-p70 interaction, we isolated a p70-interaction-deficient mutant form of XPF that contains a single amino acid substitution in the N-terminus of XPF by the reverse yeast two-hybrid assay using randomly mutagenized XPF. The biochemical properties of this RPA-interaction-deficient mutant XPF-ERCC1 are very similar to those of wild-type XPF-ERCC1 in vitro. Interestingly, expression of this mutated form of XPF in the XPF-deficient Chinese hamster ovary cell line, UV41, only partially restores NER activity and UV resistance in vivo compared to wild-type XPF. We discovered that the RPA-interaction-deficient XPF is not localized in nuclei and the mislocalization of XPF-ERCC1 prevents the complex from functioning in NER.
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PMID:Role of interaction of XPF with RPA in nucleotide excision repair. 2187 96