Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Plasmids carrying fragments of a cytochrome P-450 gene, inducible by 3-methylcholanthrene, were used to study the chromatin structure of this gene in the liver of normal and carcinogen-treated rats. Digestion with micrococcal nuclease revealed that the gene is not present in the typical 200 base pair nucleosomal structure. By use of indirect end-label hybridization, four DNase I hypersensitive sites were mapped in the 5'-terminal region of the gene. An S1 nuclease sensitive site is located close to a DNase I site. Gene induction by treatment with 3-methylcholanthrene does not result in detectable changes in the DNase I hypersensitive sites. Rat thymus chromatin does not contain DNase I hypersensitive sites in the P-450 gene, suggesting that in the liver the chromatin structure is altered so as to allow tissue-specific expression of the gene. This paper is the first study on the chromatin structure of a gene coding for a member of the cytochrome P-450 family of enzymes. The implications of our results to the understanding of gene regulation of the P-450 genes are discussed.
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PMID:Chromatin structure of a 3-methylcholanthrene-induced cytochrome P-450 gene. 407 94

Microinjection into an axon of an identified invertebrate neuron is shown to be a useful technique for analyzing the mechanisms of fast axonal transport. It permits direct assessment of the effect of agents that cannot permeate the plasma membrane on the translocation of material in the axon. The actin filament depolymerizer DNase I, when injected into the axon of the Aplysia neuron R2, caused a local block of fast transport of [3H]glycoprotein. Two agents that should interfere with the functioning of actin filaments without causing extensive depolymerization, tne N-ethylmaleimide-modified nuclease S1 fragment of myosin (injected) and dihydrocytochalasin B (applied externally). had no effect. Together these results suggest that actin plays a structural role in the axonal cytoskeleton rather than a role in transport force generation, the effect of DNase I being mediated by structural disordering of the axoplasm. Experiments were also done with inhibitors of dynein, the microtubule-associated ATPase. erythro-9-[3-(2-Hydroxynonyl)]adenine blocked transport but vanadate was ineffective.
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PMID:Microinjection into an identified axon to study the mechanism of fast axonal transport. 618 16

Plasmid pGS1 carries the Escherichia coli glyA gene and its neighboring regions on a 13-kb EcoRI insert. In a cell-free transcription-translation system, the insert directs the synthesis of two polypeptides with Mr values of about 46 500 and 45 500. When the glyA gene is inactivated with the transposable element Tn5, the Mr 46 500 polypeptide is not observed, identifying it as the glyA gene product. The Mr 45 500 polypeptide is the product of an unknown gene designated gene X. When plasmids with random insertions of the Tn5 element in either the glyA gene or gene X are used as templates in the cell-free transcription-translation system, the polypeptides observed are smaller than the glyA or X gene products. A comparison of the site of each Tn5 insertion within the glyA gene or within gene X and the size of the polypeptide observed in the cell-free system enabled us to determine the direction of transcription and translation of both genes. The glyA gene is transcribed and translated in a direction opposite to that of gene X. Nucleotide sequencing confirmed the location and orientation of the two genes in the insert. DNase I footprinting experiments defined the glyA gene and gene X control regions recognized by RNA polymerase, and S1 nuclease mapping experiments located the transcription start point for each gene. The transcription start points for the two genes are 216 bp apart, and the translation start sites are 327 bp apart. Less than 90 bp separate the two RNA polymerase molecules bound to the two promoters.
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PMID:Characterization of the Escherichia coli gene for serine hydroxymethyltransferase. 619 Jul 4

Production of 10-base multiple DNA ladder fragments during DNase I digestion of chromatin is explained by a model which does not involve site-specific nicking by the DNase I. This model was tested because it explains why 10-base (actually 10.4 base) multiple-related fragments are paradoxically generated by both endonucleolytic (DNase I) and exonucleolytic (exonuclease III) mechanisms. This new model also explains the phenomenon of substantial single-stranded DNA production during DNase I digestion of chromatin. The latter phenomenon has been widely observed but is not explained by previous models. The single-stranded gap model to be presented makes testable predictions. Primarily, these are that DNase I produces single-stranded gaps in chromatin DNA and that the termini of 10-base multiple ladder fragments are separated by single-stranded gaps. Single-stranded gap production by DNase I was confirmed by a number of methods. Sensitivity of ladder band components (from DNase I but not staphylococcal nuclease digests) to S1 nuclease suggested that the ladder fragments themselves may compose a significant portion of these gaps. Separation of ladder fragment termini by single-stranded gaps was verified by demonstrating both resistance to the nick-specific NAD+-dependent ligase and sensitivity to T4 ligase which can ligate across gaps. Many single-stranded gaps, occurring both individually and clusters, were observed by electron microscopy using either cytochrome c labeling (where the gaps) are thinner than duplex) or gene 32 protein labeling (gaps thicker than duplex). Gap sizes were estimated by protecting them with gene 32 protein and digesting away unprotected duplexes. By this method, gap sizes fall into a ladder distribution (from 10 or 20 bases up to 120 bases), which, at least in the region of the shorter sizes, clearly indicates the sizes of single-stranded gaps formed in chromatin by DNase I.
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PMID:Deoxyribonuclease I generates single-stranded gaps in chromatin deoxyribonucleic acid. 624 43

The activities of 17 endonucleases: the restriction endonucleases AvaI, Bam HI, EcoRI, HindIII, PstI and SalI, which cleave pBR322 DNA once: AluI, AvaII, CfoI, HaeIII, HhaI, HinfI, HpaII and TaqI, which cut pBR322 DNA several times, and three 'unspecific' nucleases (S1 nuclease, staphylococcal nuclease and DNase I from bovine pancreas) were determined between 0 degrees and 65 degrees C. The reaction was followed by the disappearance of covalently closed circular pBR322 DNA, using the alkaline ethidium fluorescence assay of Morgan et al. [Nucleic Acids Res. (1979) 7, 547-594]; the activity of T4 DNA ligase was similarly measured by the conversion of nicked circular DNA to closed circular DNA. For each enzyme, small aliquots of the same solution were incubated at different temperatures simultaneously in a temperature gradient device, resulting in a high relative precision. The experimental results are summarized by the simplest possible theoretical description, using linear or exponential kinetics and apparent activation energies Ea for the enzymatic reaction, Ei for the enzyme inactivation and Ti for the inactivation temperature. To a good approximation these three parameters suffice for describing the temperature dependence of the activity of most of the enzymes.
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PMID:Temperature dependence of the activity of DNA-modifying enzymes: endonucleases and DNA ligase. 627 95

The effect of chicken erythrocyte High Mobility Group protein 1 (HMG-1) on the enzymatic hydrolysis of purified double-stranded and single-stranded bacteriophage lambda DNA was studied. HMG-1 was found to inhibit the digestion of single- and double-stranded DNA by S1 nuclease and DNase I, respectively. HMG-I increased the rate of hydrolysis of double-stranded DNA by micrococcal nuclease, particularly at low HMG-1/DNA ratios, and had little effect on the hydrolysis of single-stranded DNA by micrococcal nucleases, even at high HMG-1 DNA ratios. We also present a semi-quantitative estimate that HMG-1 and HMG-2 occur in chromatin from rapidly dividing, cultured rat hepatoma cells at about 8 times the level that they occur in adult rat liver chromatin.
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PMID:Influence of nonhistone chromatin protein HMG-1 on the enzymatic digestion of purified DNA. 629 Oct 2

The adenovirus-specific DNA-binding protein (DBP) has been shown to inhibit the hydrolysis of single-stranded DNA by a DNase isolated from KB cells, (Nass, K., and Frenkel, G.D. (1980). J. Virol. 35, 314-319). The specificity of the inhibition has now been investigated. The DBP inhibits the hydrolysis of single-stranded DNA by several different DNases (DNase II, KB DNase, S1 nuclease) under a variety of reaction conditions, but it has no effect on DNase I-catalyzed hydrolysis of single-stranded DNA. The DBP also inhibits the rate of hydrolysis of double-stranded DNA by KB DNase and DNase II, but has no effect on DNase I-catalyzed hydrolysis of this substrate. The DBP also inhibits the dephosphorylation of 5'-phosphoryl-terminated DNA by bacterial alkaline phosphatase but stimulates the phosphorylation of 5'-hydroxyl-terminated DNA by polynucleotide kinase.
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PMID:DNase inhibition by the adenovirus DNA-binding protein exhibits specificity for the enzyme but not for the secondary structure of the DNA. 630 53

We show that bromoacetaldehyde, which reacts selectively at the N-1 and N-6 positions of unpaired adenine and at the N-3 and N-4 positions of unpaired cytosine residues reacts with chromosomal DNA in intact cells at probable regulatory sequences near active genes. A region of about 200 base pairs 5' to the chicken beta A-globin gene, which contains sites sensitive to nuclease S1, to several restriction endonucleases, and to very low levels of DNase I, also contains DNA structures that are preferentially sensitive to bromoacetaldehyde. These altered DNA structures are found at reproducible positions relative to the beta A-globin gene regardless of whether the bromoacetaldehyde is presented to intact erythrocytes, erythrocyte nuclei, or the beta A-globin gene itself carried in pBR322 as purified supercoiled DNA. The unpaired DNA 5' to the adult beta A-globin gene in adult erythrocytes is not detectable in embryonic erythrocytes that express embryonic beta-globin in contrast to adult beta A-globin. Our results suggest that well-defined regions of DNA with effectively unpaired bases occur in intact nuclei and that these structures may be important for specific recognition because they are tissue specific and are found at putative regulatory regions.
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PMID:Detection of an altered DNA conformation at specific sites in chromatin and supercoiled DNA. 630 20

The transcriptional activation and chromatin structure of the alpha 1-globin gene was analyzed during induced erythroid differentiation in murine erythroleukemia cells (MELC). In uninduced MELC, a low level of alpha 1-globin, coding-strand-specific transcription is detectable. Hexamethylene bisacetamide (HMBA)-mediated MELC differentiation is associated with a 10 to 20-fold increase in the rate of alpha 1-globin gene transcription. In induced MELC, alpha 1-globin gene transcription initiated predominantly near the cap site, occurs only off the coding strand, and might terminate, or attenuate, in a region 50 to 250 base-pairs 3' of the polyadenylation site. Before transcriptional activation of the gene, chromatin surrounding the gene displays overlapping DNase I and S1 nuclease sensitive sites, which map to a region 100 to 200 base-pairs 5' of the cap site. After induction, the nuclease sensitivity of these pre-established, overlapping sites increases. In addition, induction generates novel, non-overlapping DNase I and S1 nuclease sensitive sites, which map to regions centered 300 base-pairs 5', and approximately coincident with the cap site, respectively. We compared the time-course of alpha 1-globin transcriptional activation to the chromatin structure changes. A twofold increase in gene transcription is detected within two cell cycles (approximately 24 hours) of exposure of cells synchronized in the G1/early S-phase to inducer. Transcription rates continue to increase for at least 48 hours in MELC cultured with HMBA (the latest time assayed). Chromatin structure changes appear nearly complete after two cell cycles.
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PMID:Gene expression in murine erythroleukemia cells. Transcriptional control and chromatin structure of the alpha 1-globin gene. 631 18

We have examined the S1 nuclease sensitivity in the promoter of both the chicken and mouse alpha 2(I) collagen genes. When these DNAs are introduced into supercoiled plasmids and digested with S1 nuclease, a discrete region containing one or more cleavages is found in each promoter. These S1 cleavage sites were mapped by the distance of the S1 site from known restriction enzyme cleavage sites. In the chicken gene, the S1-sensitive segment is located 180 to 200 base pairs preceding the start site of transcription, whereas in the mouse promoter it is between -145 to -165 base pairs. This site in the chicken promoter maps to the segment that has previously been shown to be S1 and DNase I hypersensitive in chromatin. Although these S1 sites are found at different distances from the start site of transcription in the two promoters, the sequences at these sites are strongly conserved between the two species. Each sequence consists of an identical tandem repeat containing a short palindrome within each repeat. Since the DNA sequence does not exhibit the features that would favor either a left-handed Z-DNA configuration or a cruciform structure, an alternative model is discussed that could account for the S1 sensitivity of these sequences. The conservation of these sequences and their S1 sensitivity suggests they play a role in the activation or regulation of the alpha 2(I) collagen gene promoters.
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PMID:A sequence conserved in both the chicken and mouse alpha 2(I) collagen promoter contains sites sensitive to S1 nuclease. 632 89


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