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

Apurinic/apyrimidinic (AP) sites in cellular DNA are considered to be both cytotoxic and mutagenic, and can arise spontaneously or following exposure to DNA damaging agents. We have isolated cDNA clones which encode an endonuclease, designated HAP1 (human AP endonuclease 1), that catalyses the initial step in AP site repair in human cells. The predicted HAP1 protein has an Mr of 35,500 and shows striking sequence similarity (93% identity) to BAP 1, a bovine AP endonuclease enzyme. Significant sequence homology to two bacterial DNA repair enzymes, E. coli exonuclease III and S. pneumoniae ExoA proteins, and to Drosophila Rrp1 protein is also apparent. We have expressed the HAP1 cDNA in E. coli mutants lacking exonuclease III (xth), endonuclease IV (nfo), or both AP endonucleases. The HAP1 protein can substitute for exonuclease III, but not for endonuclease IV, in respect of some, but not all, DNA repair and mutagenesis functions. Moreover, a dut xth (ts) double mutant, which is nonviable at 42 degrees C due to an accumulation of unrepaired AP sites following excision of uracil from DNA, was rescued by expression of the HAP1 cDNA. These results indicate that AP endonucleases show remarkable conservation of both primary sequence and function. 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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PMID:Isolation of cDNA clones encoding a human apurinic/apyrimidinic endonuclease that corrects DNA repair and mutagenesis defects in E. coli xth (exonuclease III) mutants. 171 77

6-Benzylaminopurine (6-BAP) (1 mg/ml) does not influence the growth of E. coli B cell cultures or the number of [8-14C] labeled N6-methyladenine (m6A) residues in the total DNA [(100.m6A/(A x m6A) = 1.7]. The growth of bacterial cells in the presence of adenine or cytokinins (6-BAP, kinetin, zeatin) (1 mg/ml) was unaccompanied by significant changes in the intracellular content of plasmid pBR 322. The mode of restriction by endonuclease Cfu I hydrolyzing the Gm6ATC site of plasmids pBR 322 from E. coli B cells grown in the presence of adenine or one of the above-mentioned cytokinins is identical. These plasmids also have identical restriction products Mbo I or Sau 3AI. Thus, the cytokinins under study do not markedly affect the methylation of adenine residues in total DNA of E. coli B cell cultures and the GATC sequence in plasmids pBR 322 isolated from these cells.
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PMID:[Cytokinins do not noticeably change the methylation of adenine residues of DNA in cultured Escherichia coli B]. 269 Sep 61

Drosophila Rrp1 (Recombination repair protein 1) belongs to a family of DNA repair nucleases that includes Escherichia coli exonuclease III, Streptococcus pneumoniae exonuclease A, bovine BAP, mouse APEX endonuclease, and human APE. Within a 252 amino acid region, colinear homology is shared between all members. Rrp1 is unique in that it includes a 427 amino acid N-terminal region not related to any known sequence. The protein copurifies with an apurinic endonuclease and a double-stranded DNA 3'-exonuclease. In this study, a 5'-end-labeled 37 base pair oligonucleotide substrate containing a single apurinic site was used to characterize the endonuclease activity of Rrp1. This substrate is utilized efficiently by Rrp1: the specific activity observed is 1 x 10(5) units/mg. The abasic double-stranded DNA oligonucleotide is cleaved only at the abasic site to create a single-strand break. Strand breaks are not detected in the complementary strand, in the single-stranded DNA oligonucleotide, or in the base-paired control substrate. After endonucleolytic cleavage at the abasic site, exonucleolytic processing at the nick is slow and requires a molar excess of Rrp1, while exonuclease III degrades the nicked substrate more efficiently. The Rrp1 cleavage product comigrates with a DNaseI cleavage product, and the newly formed terminus supports DNA synthesis by DNA polymerase. Therefore, Rrp1 cleaves the phosphodiester backbone at one position 5' to the apurinic site and leaves a 3'-hydroxyl terminus. Rrp1 is a class II apurinic endonuclease and is likely to be important in DNA repair in Drosophila.
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PMID:Characterization of the apurinic endonuclease activity of Drosophila Rrp1. 769 63

The synthesis of oligodeoxynucleotides (ODNs) containing 5-[N-[2-[N,N-bis(2-aminoethyl)amino]ethyl]-carbamoyl]-2'-deoxyuridine (BAE) and 5-[N-[3-[N,N-bis(3-aminopropyl)amino]propyl]carbamoyl]-2'- deoxyuridine (BAP) is described. The thermal stabilities of duplexes containing these ODNs and either the complementary DNA or RNA strand and of triplexes consisting of these ODNs and the target duplex were studied by thermal denaturation. ODNs containing BAE or BAP stabilize duplex formation with either the complementary DNA or RNA strands but destabilize triplex formation with the target duplex. Furthermore, the resistance of these ODNs to nuclease hydrolysis was studied by using snake venom phosphodiesterase (a 3'-exonuclease) and nuclease S1 (an endonuclease). It was found that ODNs containing either BAE or BAP were more resistant to nucleolytic hydrolysis by either of the nucleases than the unmodified ODN.
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PMID:Nucleosides and nucleotides. 170. Synthesis and properties of oligodeoxynucleotides containing 5-[N-[2-[N,N-bis(2-aminoethyl)- amino]ethyl]carbamoyl]-2'-deoxyuridine and 5-[N-[3-[N,N-bis(3-aminopropyl) amino]propyl]carbamoyl]-2'-deoxyuridine. 946 May 44