Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Superhelical [3-H]DNA (replicative form I, RFI) of bacteriophage phiX174 slowly but spontaneously took up 32-P-labeled homologous single-stranded fragments at 4 degrees. Uptake was accelerated by heating to 75 degrees. RFI did not take up single-stranded fragments derived from DNA of Escherichia coli or from separated strands of phage lambda. Uptake was inhibited by low concentrations of ethidium bromide. Relaxed circular phiX174 DNA did not take up homologous fragments. Per molecule of RFI, the complexes contained as much as 90 nucleotide residues of homologous fragment. The 32-P-lebeled fragments were largely resistant to digestion by exonuclease I, and were not displaced by heating complexes at 60 degrees for 1 min in 16 mM or 100 mM NaCl. Under comparable conditions of temperature and salt all of the fragments were displaced from complexes in which at least one phosphodiester bond was cleaved by pancreatic DNase, but a significant fraction of the fragments was retained in complexes that were relaxed by digestion with S1 nuclease. These observations are interpreted to mean that S1 nuclease digested the plus (viral) strand of the recipient RF at the site of uptake in some instances. Transfection of E. coli by heterozygous complexes produced recombinant progeny, thereby showing that genetic information can be transferred from the fragment of plus strand to progeny plus strands. We propose that both uptake of a third strand by superhelical DNA and the action of nucleases on the resulting complex may simulate early steps in genetic recombination.
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PMID:Uptake of homologous single-stranded fragments by superhelical DNA: a possible mechanism for initiation of genetic recombination. 109 67

The complete nucleotide sequence of the structural gene for Escherichia coli exonuclease I has been determined. The coding region corresponds to a 465-amino acid protein with molecular weight of 53,174. The partial amino acid sequence of purified exonuclease I agrees with that predicted by the DNA sequence. Two putative weak promoters have been localized by S1 nuclease analysis. The sbcB coding sequence contains many non-optimal codons, characteristic of many poorly expressed E. coli genes.
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PMID:Determination of the nucleotide sequence for the exonuclease I structural gene (sbcB) of Escherichia coli K12. 353 37

Hybridization of heterologous nucleic acids has provided the means for isolating a repeating sequence which is located next to template regions of DNA. Separated single strands of 32P-labelled DNA from Escherichia coli were to a limited extent able to anneal with DNA of Micrococcus lysodeikticus immobilized on nitrocellulose membrane filters. The resulting hybrid was resistant to enzymes specific for unpaired strands, nuclease S1 (Aspergillus oryzae) and exonuclease I (E. coli). The E. coli DNA so hybridized was isolated and characterized. It contained all four bases with cytosine predominating; strand length was about 50-60 nucleotides. Since these units occupied about 1-2% of the length of the E. coli chromosome, they would have to be repeated about 2000 times in a single cell. Formation of the unusual hybrid was not diminished by prior saturation of the E. coli DNA with homologous 3H-labelled RNA. In fact both RNA and additional increments of DNA were detected on the filters approximately in a 1:1 ratio, showing that some of the repeating sequences were physically continuous with transcribed regions of DNA.
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PMID:Isolation of a short, cytosine-rich repeating unit from the DNA of Escherichia coli. 1140 Apr 31

Here, we examined the effects of molecular crowding on the function, structure and stability of nucleases. We found that the hydrolysis of a 29-mer double-stranded DNA by the endonucleases DNase I and S1 nuclease was substantially enhanced by molecular crowding using polyethylene glycol (PEG); however, molecular crowding had little effect on hydrolysis by exo III and exo I exonucleases. Moreover, kinetic analysis showed that the maximum velocity for the reaction of DNase I at 25 degrees C was increased from 0.1 to 2.7 microM/min by molecular crowding with 20% (w/v) PEG, whereas that of exonuclease I at 37 degrees C decreased from 2.2 to 0.4 microM/min. In contrast, molecular crowding did not significantly affect the Michaelis constant of DNase I or exonuclease I. These results indicate that molecular crowding has different effects on the catalytic activities of exonucleases and endonucleases.
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PMID:Regulation of DNA nucleases by molecular crowding. 1756 1

Micrococcal nuclease (MNase) is a nonspecific endo-exonuclease that digests single-stranded/double-stranded DNA and RNA. The existence of MNase can serves as an important diagnostic biomarker of Staphylococcus aureus (S. aureus) infection. However, most of the substrates in MNase-based sensors are single-stranded DNA, which could also be digested by exonuclease I or S1 nuclease and interfere the MNase detection. In this work, we developed a highly selective fluorescent method for MNase detection using a specific dsDNA and nucleic acid dye SYBR Green I (SGI) as the indicator. After rational design, an AT-rich dsDNA with 3' protruding termini was screened as the high-specific substrate of MNase assay and efficient enhancer of SGI. The AT-rich dsDNA substrate can resist the digestion of other exonuclease and greatly enhance the fluorescence of SGI. This high-specific substrate-based probe can detect MNase in buffer as well as biological sample with highly selectivity. Moreover, this method was also applied to monitor the MNase secreted by S. aureus. Thus, the proposed MNase-based assay has a strong potential to identify S. aureus in food safety and microbial infection due to its excellent analytical sensitivity and high selectivity.
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PMID:High specific MNase assay for rapid identification of Staphylococcus aureus using AT-rich dsDNA substrate. 3135 54