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:3.1.31.1 (micrococcal nuclease)
2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three major satellite DNAs comprise 40-45% of the genome of Drosophila virilis. Since these satellites are not substrates for most restriction enzymes, we were able to digest D. virilis nuclei with HaeIII and micrococcal nuclease and isolate chromatin fractions containing variable levels of satellite DNA. Electrophoretic analysis of these chromatin fractions revealed that the level of the acid-soluble chromosomal protein, cp17.3, was directly related to the percentage of satellite DNA in chromatin. The correlation between cp17.3 and satellite DNA abundance suggests that cp17.3 is involved in the heterochromatic condensation of satellite DNAs. cp17.3 occurs at a frequency of one molecule per 10-20 nucleosomes. It is detected in an electrophoretically distinguishable class of mononucleosomes, provisionally identified as MN1uH2A, which contains ubiquitinated histone H2A (uH2a) but lacks histone H1. It is not detected in MN1, a second class of mononucleosomes, which lacks uH2A and H1. Since cp17.3 is correlated with satellite DNAs and present in nucleosome cores, it might be a histone variant specifically associated with satellite DNAs.
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PMID:Satellite DNA-correlated nucleosomal proteins in Drosophila virilis. 300 8

To investigate the chromatin surrounding an active gene, we have determined the distribution of RNA polymerase molecules, the intactness of nucleosomal structure, and the subnuclear compartmentalization along 15 kilobase pairs (kb) of the mouse kappa immunoglobulin locus of MPC-11 plasmacytoma cells. Hybridization of in vitro nuclear transcripts to probes specific for the template strand reveals that transcription terminates within the region between 1.1 and 2.3 kb downstream from the poly(A) addition site. Ten different short sequences (8-13 base pairs) reside within 460 base pairs of this termination region that exhibit homology with sequences found in the termination regions of mouse beta-globin and chicken ovalbumin genes. Transcription of the nontemplate strand occurs on either side of this termination region. We find that both within the transcription unit and 6.5 kb downstream of the termination region of the kappa gene, the canonical nucleosomal structure is perturbed, the chromatin exhibits pronounced insolubility, and the nucleosomes liberated by micrococcal nuclease appear to lack histone H1. The insolubility is characterized by interactions that are disrupted by 0.3 to 0.6 M NaCl treatment. We conclude that the active chromatin phenotype spreads a considerable distance along the kappa locus, well beyond the region of transcription termination.
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PMID:Transcription termination and chromatin structure of the active immunoglobulin kappa gene locus. 308 10

By means of selective micrococcal nuclease digestion chromatin from early stages of the sea urchin St. droebachiensis embryogenesis was divided into fractions differing by their transcriptional activity. The electrophoretic analysis of histones at the gastrula stage showed that the transcriptionally active chromatin fraction was enriched with early variants of histone H2A and H1. On the stage of pluteus, when primary cell differentiation is completed, the amount of total histone H1 in this fraction was significantly decreased, however it was enriched in an early alpha variant. It was shown that after mild micrococcal nuclease digestion mononucleosomes, which were mostly derived from active chromatin, were significantly enriched with in vivo labeled early histone variants.
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PMID:[Nucleosomes of active chromatin from sea urchin embryo cells are rich in early histone variants]. 337 87

We have compared mononucleosomes that were obtained by hydrolysis of chromatin micrococcal nuclease from a number of sources with the length of a nucleosomal repeat 185--245 b. p. long. For hydrolysis of chromatin isolated from nuclei, a series of nucleosomes was formed: MN145 (core particle), MN165, MN175...MN205, MN215, the lengths of their DNAs differing (by approximately 10.n b.p. where n = 1, 2, 3...) by a factor of 10. A feature of hydrolysis of chromatin in nuclei was the appearance of an additional H1-depleted MN155 particle. It is suggested that upon isolation of chromatin from nuclei, its partial decompactization takes place. This decompactization changes the character of nuclease splitting and seems to be connected with rearrangement of histone H1. These observations demonstrate that besides core particles MN145 and chromatosomes MN165, the major particles of digest of nuclei appear to be MN155, and for isolated chromatin--MN175. Unlike this standard picture, mainly MN145, MN155, MN235 and MN245 are formed upon hydrolysis of sea urchin sperm nuclei.
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PMID:[Structure of nucleosomes and organization of inter-nucleosomal DNA in chromatin]. 339 53

In murine L-cell nuclei micrococcal nuclease causes chromatin fragmentation with predominant liberation of dinucleosomes. Analysis of dynamics of rat liver nuclear chromatin cleavage by micrococcal nuclease revealed that the "dinucleosomal" mode of fragmentation is due to the pretreatment of nuclei with the non-ionic detergent Triton X-100 in the course of the isolation procedure. The set of particles detected in nuclease hydrolysates of nuclear chromatin pretreated with Triton X-100 and those isolated by the standard procedure was shown to be significantly different. In Triton X-100 treated nuclei the dichromatosome is the main hydrolysate component under various experimental conditions of nuclease hydrolysis and the sole component under "mild" conditions, whereas sucrose-treated nuclei contain three types of dinucleosomes. In Triton-treated nuclei prolongation of hydrolysis results in the liberation of the chromatosome which is absent in chromatin hydrolysates of sucrose-treated nuclei. Hydrolysis of Triton-treated nuclear chromatin by micrococcal nuclease is unaccompanied by the liberation (up to the stage of "deep" hydrolysis) of the core particle, the major component of the "sucrose" nuclear hydrolysate under the conditions used. The sharp differences in the accessibility of various types of dinucleosomes observed during pretreatment of nuclei with Triton X-100 are interpreted in terms of the localization of histone H1. The non-random type of the histone H1 molecule orientation along the nucleosome fibril is postulated.
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PMID:[Internucleosome interaction: detection of dinucleosome fragmentation of chromatin by micrococcal nuclease. Analysis of the products of cleavage of chromatin from rat liver nuclei and L cells by micrococcal nuclease]. 344 Jan 14

The chromatin-bound histone deacetylase of Chinese hamster ovary cells has been studied by using as a substrate an acetylated amino-terminal peptide of histone H4. These studies demonstrate that histone deacetylase activity is associated with mononucleosomes solubilized by digestion with micrococcal nuclease. The deacetylase activity remained bound to the nucleosomes, even in the presence of 1 M NaCl. This unique class of deacetylase-associated mononucleosomes is resolved from the major classes of mononucleosomes by polyacrylamide gel electrophoresis. These mononucleosomes contain 290 and 190 base pair DNAs and demonstrate the presence of histone H1 and non-histones HMG-1 and HMG-2 and the absence of HMG-14 and HMG-17. They are further characterized by a specific acetylation pattern of histone H4 and likely represent a functionally important chromatin-DNA complex.
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PMID:A Chinese hamster ovary cell histone deacetylase that is associated with a unique class of mononucleosomes. 344 54

The content of histone H1 (H1/H4 ratio) in dinucleosomes with the DNA of various length liberated from L-cell nuclear chromatin by micrococcal nuclease was analyzed. It was found that the histone H1 content in the dichromatosome is two times as low as that in the largest dinucleosome and in the complete mononucleosome. The set of chromatin fragments liberated from the Triton X-100 pretreated nuclei differs considerably from that of chromatin sites devoid of histone H1 (the de novo replicating chromatin and the chromatin formed on the undermethylated DNA). A scheme for asymmetric distribution of histone H1 with molecules oriented along the nucleosomal fibril, which reflects the peculiarities of chromatin fragmentation by micrococcal nuclease with predominant liberation of the dichromatosome, is proposed.
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PMID:[Internucleosome interactions: detecting the dinucleosome fragmentation of chromatin using micrococcal nuclease. Heterogeneity of nucleosomes and localization of histone H1]. 344 29

A protease activity associated with the micrococcal nuclease-solubilized chromatin from mouse seminiferous tubules has been characterized. Proteolysis of histone H1 and core histones is stimulated in the presence of 3 M urea. The pH optimum of this protease is between pH 8 and 9, and the activity is not inhibited by trypsin or chymotrypsin-active site inhibitors. Leupeptin is an effective inhibitor of the protease at low concentrations. Soluble chromatin from neonatal and prepubertal mice lacks this proteolytic activity until three to four weeks after birth. That the protease activity is localized in the dinucleosomes and higher oligomers but is lacking in mononucleosome populations suggests its association with the linker DNA. Rat testis-soluble chromatin apparently lacks such a protease activity. The developmental expression of this protease and its in situ localization are consistent with a role in histone displacement during mouse spermiogenesis.
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PMID:A protease activity is associated with testicular chromatin of the mouse. 355 31

The size distribution of chromatin fragments released by micrococcal nuclease digestion of liver chromatin at various ionic strengths was examined. Below 20 mM ionic strength, gradient profiles with a peak centered at 6 nucleosomes are generated, whereas between 20 and 50 mM the peak is always centered on 12 nucleosomes, and above 50 mM ionic strength the 30-nm fiber becomes less accessible to the nuclease and there is a corresponding increase in the size distribution of fragments in the gradients. However, extensive digestions always give profiles with a peak of 12 nucleosomes as nuclease-resistant dodecamers accumulate. All of these observations are consistent with the winding of the 10-nm polynucleosome chain into a helical coil commencing at about 20 mM ionic strength. The helical turns are stabilized by histone H1 interactions between 20 and 50 mM ionic strength producing stable dodecamers. Above 50 mM ionic strength the coil condenses longitudinally and the profiles are consistent with a random attack of this fiber by the nuclease. Consequently it is not necessary to invoke the existence of a subunit bead to explain the profiles. We further define the conditions at which specific structural transitions take place and provide methodology for the preparation of chromatin at various levels of condensation.
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PMID:Chromatin structure. Further evidence against the existence of a beaded subunit for the 30-nm fiber. 362 52

Conditions have been found for the isolation of rat liver nuclei which maintain chromatin in its native state and suppresses endogenous nuclease activity. Chromatin prepared in this way can be dispersed into buffers containing various concentrations of monovalent or divalent cations so that the 30-nm fiber is either totally or partially decondensed. When probed with micrococcal nuclease, the digestion profiles show that although the 30-nm fiber can be cleaved periodically to generate superbead-like particles this only occurs under certain ionic conditions when the fiber is partially decondensed. It is likely that this cleavage pattern reflects the transient exposure of specific nuclease sensitive sites as the 30-nm fiber condenses, rather than the existence of a specific subunit of a beaded 30-nm fiber. The periodicity of these nuclease-sensitive sites appear to be related to the asymmetric distribution of histone H1 molecules along the length of the fiber.
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PMID:Chromatin structure. Nuclease digestion profiles reflect intermediate stages in the folding of the 30-nm fiber rather than the existence of subunit beads. 370 Apr 26


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