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)

Mitochondrial (mt) DNA from four sibling species within the Paramecium aurelia complex, including stocks of different geographic origin and mutants, were analyzed using four 6-bp recognition site and one 4-bp recognition site endonucleases and the sequence divergence was estimated using Upholt's (1977) statistical procedure. All four species were readily distinguishable regardless of the restriction endonuclease employed. With intraspecies comparisons, no differences were observed which could be accounted for on the basis of geographic origin. Except for species 4, each stock (and mutant) gave a species-specific fragment pattern. For species 4, while the patterns were distinct from the other species, two species-specific type of patterns were found, designated A and B. The sequence divergence between these was estimated to be between 1 and 2 percent. With interspecies comparisons, the sequence divergence ranged from 3.9 to 10.3% with the greatest divergence being between species 1 and 4, and the least between species 1 and 5. The similarity between species 1 and 5 is in accord with other criteria for interspecies comparisons. The degree of sequence divergence measured here in Paramecium mt DNA is well within the range reported for rodents and primates. All four species mt DNA were cleaved to many DNA fragments by DPN II, an enzyme which recognizes non-methylated sites, and not by DPNI, the methyl-site specific counterpart of DPN II, suggesting that mt DNA from Paramecium aurelia is not appreciably methylated, if at all.
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PMID:Evolutionary divergence of mitochondrial DNA from Paramecium aurelia. 625 97

Hjc resolvase is an archaeal enzyme involved in homologous DNA recombination at the Holliday junction intermediate. However, the structure and the catalytic mechanism of the enzyme have not yet been identified. We performed database searching using the amino acid sequence of the enzyme from Pyrococcus furiosus as a query. We detected 59 amino acid sequences showing weak but significant sequence similarity to the Hjc resolvase. The detected sequences included DPN:II, HAE:II and Vsr endonuclease, which belong to the type II restriction endonuclease family. In addition, a highly conserved region was identified from a multiple alignment of the detected sequences, which was similar to an active site of the type II restriction endonucleases. We substituted three conserved amino acid residues in the highly conserved region of the Hjc resolvase with Ala residues. The amino acid replacements inactivated the enzyme. The experimental study, together with the results of the database searching, suggests that the Hjc resolvase is a distantly related member of the type II restriction endonuclease family. In addition, the results of our database searches suggested that the members of the RecB domain superfamily are evolutionarily related to the type II restriction endonuclease family.
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PMID:Hjc resolvase is a distantly related member of the type II restriction endonuclease family. 1107 43

Properties of a mutant bacteriophage T2 DNA [N:(6)-adenine] methyltransferase (T2 Dam MTase) have been investigated for its potential utilization in RecA-assisted restriction endonuclease (RARE) cleavage. Steady-state kinetic analyses with oligonucleotide duplexes revealed that, compared to wild-type T4 Dam, both wild-type T2 Dam and mutant T2 Dam P126S had a 1.5-fold higher k(cat) in methylating canonical GATC sites. Additionally, T2 Dam P126S showed increased efficiencies in methylation of non-canonical GAY sites relative to the wild-type enzymes. In agreement with these steady-state kinetic data, when bacteriophage lambda DNA was used as a substrate, maximal protection from restriction nuclease cleavage in vitro was achieved on the sequences GATC, GATN and GACY, while protection of GACR sequences was less efficient. Collectively, our data suggest that T2 Dam P126S can modify 28 recognition sequences. The feasibility of using the mutant enzyme in RARE cleavage with BCL:I and ECO:RV endonucleases has been shown on phage lambda DNA and with BCL:I and DPN:II endonucleases on yeast chromosomal DNA embedded in agarose.
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PMID:Methylation by a mutant T2 DNA [N(6)-adenine] methyltransferase expands the usage of RecA-assisted endonuclease (RARE) cleavage. 1126 50