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

Superhelical covalently closed circular replicative form DNA (RF I) of coliphage M13 appears as a relaxed molecule that has a base-unpaired region in the form of a bubble (100 to 200 base pairs long) seen in electron micrographs when spread in the presence of formaldehyde and formamide or after pretreatment with glyoxal. S1 endonuclease, specific for single-stranded DNA, converts superhelical M13 RF I DNA, but not nonsuperhelical M13 RF I to a significant extent, into unit-length linear molecules by sequential nicking of two strands. The locations of S1 nuclease-susceptible sites and glyoxal-fixed base-unpaired regions were both related to the five A-T-rich regions in M13 RF DNA. While S1 nuclease does not show preference for any of these sites, glyoxal-fixed bubbles occur predominantly at the major A-T-rich region in M13 RF DNA.
 ...
PMID:Base-unpaired regions in supercoiled replicative form DNA of coliphage M13. 32 5

The conformation of calf thymus DNA modified by reaction with (+/-)-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy7,8,9,10-tetrahydrobenzo[a]pyrene, which binds covalently mainly to the 2-amino group of guanosine residues, was studied. With samples in which 1.5 or 2.2% of the bases were modified, there was a slight decrease in Tm during heat denaturation and a slight increase in susceptibility to the single strand specific nuclease S1. In a DNA sample in which 4.5% of the bases were modified, there was an appreciable decrease in Tm and a marked increase in susceptibility to S1 nuclease. The kinetics of the reaction of the modified DNAs with formaldehyde provided evidence for locally destabilized regions ranging from 1 to 7 base plates, depending on the extent of modification. Alkaline and neutral sucrose gradient analyses revealed no evidence for strand breakage in the 1.5 and 2.2% modified samples, although single-strand breaks were found in the 4.5% modified samples. Taken together, these results suggest that DNA molecules containing a covalently bound benzo[a]pyrene derivative have an altered conformation characterized by small localized regions which are destabilized and easily denatured. The conformational changes associated with the covalent binding of the benzo[a]pyrene derivative to native DNA appear to be different from, and less marked, than those associated with the covalent binding of N-2-acetylaminofluorene to native DNA.
 ...
PMID:Conformation of DNA modified with a dihydrodiol epoxide derivative of benzo[a]pyrene. 56 Aug 57

The single-strand specific nuclease S1 from Aspergillus oryzae (EC 3.1.4.21) was purified 600-fold in 16% yield from dried mycelia. Determination of the isoelectric point of S1 nuclease as 4.3-4.4 allowed adjustment of chromatographic conditions such that the enzyme was isolated free of contaminating ribonucleases T1 and T2. S1 nuclease so purified was used for removal of single-stranded portions from the RNA of the Escherichia coli phage MS2, which has a helical content of about 65% in vitro. At 23 degrees, increasing amounts of enzyme converted the RNA to mononucleotides in about equimolar base ratios. No small intermediates of chain length 2-8 were found. At 0 degrees, MS2 RNA hydrolysis was slower and reached, in exhaustive digests, a plateau where 70% of the substrate RNA remained insoluble in 66% EtOH. With [32P]MS2 RNA, strip chart counting of 6% acrylamide-6 M urea electrophoresis patterns of such digests gave recoveries of 80-91% in the form of defined oligomer bands. On 2.5% acrylamide-0.5% agarose gels, the molecular weights of the major oligomers were found to range from 25,000 to 41,000. Similar to purified tRNAArg used as a control, these oligomers were not resistant to pancreatic RNase-RNase T1 hydrolysis at 37 degrees, and were not bound on hydroxylapatite at 50 degrees in 0.14 M sodium phosphate (pH 6.8). Melting of the oligomers gave complex profiles without a clear Tm and showed an increase in A260 of 35% at 93 degrees over that at 28 degrees. Upon formaldehyde denaturation of MS2 RNA prior to S1 nuclease hydrolysis, no resistant oligomers were found.
 ...
PMID:S1 nuclease hydrolysis of single-stranded nucleic acids with partial double-stranded configuration. 118 98

Highly purified recombinant human tumor necrosis factor (TNF) was found to induce interleukin 1 (IL 1) production in diploid human FS-4 fibroblasts. Demonstration of IL 1 activity was based on the ability of TNF-treated FS-4 cells, subsequently fixed with formaldehyde, to stimulate thymocyte proliferation in the presence of phytohemagglutinin. Incubation of FS-4 cells with the optimal dose of TNF (10 ng/ml) resulted in a marked increase in [3H] thymidine uptake by thymocytes co-cultured with formaldehyde-fixed FS-4 cells. Induction of this apparently membrane-associated IL 1 (MA-IL 1) activity was demonstrable at 6 hr and reached a plateau after 48 hr of incubation with TNF. FS-4 cells did not secrete soluble IL 1 in response to TNF. Dexamethasone suppressed the synthesis of TNF-induced MA-IL 1. A monoclonal antibody specific for TNF neutralized MA-IL 1 induction, indicating that the induction is due to TNF, and not to a contaminant in the TNF preparation. The ability of TNF to induce IL 1 synthesis in FS-4 fibroblasts at the transcriptional level was confirmed by S1 nuclease protection assay. Cytoplasmic RNA from uninduced FS-4 cells contained no demonstrable RNA hybridizing with a human IL 1-alpha cDNA probe and low levels of RNA hybridizing with an IL 1-beta cDNA. Induction with TNF resulted in the appearance of IL 1-alpha mRNA and a very significant increase in IL 1-beta mRNA, indicating that TNF induces the synthesis of both IL 1-alpha and IL 1-beta in FS-4 cells.
 ...
PMID:Induction of membrane-associated interleukin 1 by tumor necrosis factor in human fibroblasts. 349 60

With the application of radioactive formaldehyde and glycine the ability of aminomethylol compounds to combine with S1 nuclease treated DNA at 25 degrees and pH 5.8--7.4 has been shown. The reaction leads to modification of 22--26% of base pairs without changes of the DNA UV-absorption spectrum. Besides that the flexibility coefficient, the kinetics of despiralization under the action of formaldehyde and the stability of DNA molecule towards the S1 nuclease action permit to conclude that modification does not cause DNA despiralization. In experiments with the use of synthetic double-stranded polynucleotides poly(dA) times poly(dT), poly(rC) times poly(rl), poly(rG) times poly(dC) and poly(dC-dG) times poly(dC-dG) it has been shown that binding of methylol compounds to nucleic acids is due to reaction with guanine residues. Methylol derivatives of glycine reacts with guanine residues of double-stranded DNA only 10 times slower than with the monomer--deoxyguanosine-5'-phosphate. The studied reaction is reversible and the half-period of modified DNA reduction is found to be 5 hours at 25 degrees and pH 6.5. The rate constants of forward and reverse reactions and equilibrium constants of the reaction between methylolglycine and native DNA were determined.
 ...
PMID:[Modification of guanine residues in double-stranded DNA by aminomethylol compounds without denaturation of nucleic acid]. 627 61

We have analyzed the differential expression of a family of beta-like globin genes during the development of rabbits, from four days post implantation to one week before birth. The family is composed of four genes, arranged 5'-beta 4-beta 3-psi beta 2-beta 1-3' on the chromosome; psi beta 2 is an inactive pseudogene. Using the technique of hybrid-arrested translation in vitro, we have identified the embryo-specific globin polypeptides encoded by genes beta 3 and beta 4. The beta 3 and beta 4 globins are replaced by the adult beta 1 globin halfway through gestation; this corresponds temporally with the switch in site of erythropoiesis from the embryonic yolk sac to the fetal liver. The decline in production of beta 3 globin polypeptide precedes the decline in beta 4 globin. Transcripts from genes beta 1, beta 3 and beta 4 were analyzed at progressive stages of gestation by a blot-hybridization assay and by an S1 nuclease protection assay. Mature messenger RNA and presumptive precursor RNAs from genes beta 3 and beta 4 are synthesized abundantly in embryonic erythroid cells but only at very low levels later in fetal development. Conversely, precursor and mature mRNA from gene beta 1 are found at very low levels in embryos but are abundant in fetal and adult erythroid cells. The co-ordinate appearance of precursor RNA, mRNA and polypeptide from all three active genes indicates that the primary developmental regulation of this gene family is exerted at the level of transcription. RNA species larger than the expected precursors were observed when the RNA was denatured with formaldehyde but not when methylmercury was the denaturant. These large RNAs are a formaldehyde-generated artifact, possibly a result of cross-linking globin transcripts to ribosomal RNA. We observe no extensive stable transcripts from the 5' or 3' flanking regions of these genes.
 ...
PMID:Analysis of rabbit beta-like globin gene transcripts during development. 684 97

Bean golden yellow mosaic virus (GYMV) DNA sedimented in sucrose density gradients and in an analytical ultracentrifuge as a single component. Values of s(20,w) which depended upon ionic strength (i) and pH, were 16.0 (pH = 7.0, i = 0.1); 16.3 (pH = 7.0, i = 1.0); 9.0 (pH = 13, i = 0.1); and 12.0 (0.1 N NaOH, i = 1.0). GYMV-DNA banded in CsCl as a single component with a buoyant density of 1.7170 g/ml and exhibited hyperchromicity when heated between 20 and 70 degrees . Hyperchromicity and a shift in the ultraviolet light absorption maximum were observed when the DNA was treated with formaldehyde (1.8%) at room temperature. Nuclease sensitivity tests showed that the DNA was susceptible to hydrolysis by DNase I and nuclease S1 (specific for single-stranded DNA) but not to hydrolysis by RNase A or by 0.3 N NaOH. Molecular weight values calculated from sedimentation velocity and CsCl equilibrium data were in the range of 0.66 to 0.95 x 10(6) daltons GYMV thus contains DNA with the properties of a predominantly single-stranded molecule and represents the first reported single-stranded DNA virus from plants.
 ...
PMID:Single-stranded DNA genome in a whitefly-transmitted plant virus. 1862 85