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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined in the H4IIE rat hepatoma cell line the relationship between butyrate-induced changes in the nuclease sensitivity of chromatin and changes in transcriptional activity of specific genes. The butyrate-inducible metallothionein I (MT-I) gene underwent a dramatic increase in DNase I sensitivity after 3 h of butyrate treatment. However, genes not transcribed in H4IIE cells underwent the same changes in DNase I sensitivity. Thus, butyrate-induced increases in DNase I sensitivity are not sufficient for the transcriptional activation of a gene. Butyrate treatment has also been reported to alter the sensitivity of sequences to micrococcal nuclease (MNase) in a manner reflecting their tissue-specific expression. Butyrate exposure caused increased digestion of the MT-I gene by MNase. However, butyrate-induced MNase sensitivity also occurred for genes which are neither transcribed in untreated cells nor butyrate inducible. Moreover, cadmium, a potent transcriptional activator of the MT-I gene, does not alter the sensitivity of the MT-I gene to MNase. Thus, the butyrate-induced alterations in MNase sensitivity are neither sufficient for, necessary for, nor indicative of transcriptional activation.
Mol Cell Biol 1987 Nov
PMID:Butyrate-induced changes in nuclease sensitivity of chromatin cannot be correlated with transcriptional activation. 343 45

Previous work has shown that DNA and the histone proteins will combine to form structures of a complex, yet definite nature. Here, we describe three experiments aimed at a better understanding of the interactions of DNA with the histone octamer and with histone H5. First, there has been some question as to whether the methylation of DNA could influence its folding about the histone octamer. To address this point, we reconstituted the histone octamer onto a 440 base-pair DNA of defined sequence at various levels of cytosine methylation, and also onto the unmethylated DNA. The reconstituted structures were probed by digestion with two different enzymes, micrococcal nuclease and DNase I. All samples were found to contain what appear to be three histone octamers, bound in close proximity on the 440 base-pair DNA. The cutting patterns of micrococcal nuclease and DNase I remain the same in all cases, even if the DNA has been extensively methylated. The results show, therefore, that methylation has little, or no, influence on the folding of this particular DNA about the histone octamer. Second, there has been concern as to whether the base sequence of DNA could determine its folding in a long molecule containing several nucleosomes, just as it does within any single, isolated nucleosome core. In order to deal with this problem, we cut the 440 base-pair DNA into three short fragments, each of nucleosomal length; we reconstituted each separately with the histone octamer; and then we digested the reconstituted complexes with DNase I for comparison with similar data from the intact 440 base-pair molecule. The results show that the folding of this DNA is influenced strongly by its base sequence, both in the three short fragments and in the long molecule. The rotational setting of the DNA within each of the three short fragments is as predicted from a computer algorithm, which measures its homology to 177 known examples of nucleosome core DNA. The rotational setting of the DNA in the 440 base-pair molecule remains the same as in two of the three short fragments, but changes slightly in a third case, apparently because of steric requirements when the nucleosomes pack closely against one another. Finally, there has been little direct evidence of where histone H5 binds within a DNA-octamer complex.(ABSTRACT TRUNCATED AT 400 WORDS)
J Mol Biol 1987 Oct 05
PMID:Structural analysis of a reconstituted DNA containing three histone octamers and histone H5. 344 Oct 8

Peptides derived from calf thymus H1 and rat liver H1, comprising only the globular and COOH-terminal domains of the intact molecule and therefore lacking NH2-terminal domains, have been shown by reconstitution to be as effective as the complete H1 molecule in inducing higher-order-chromatin structure. As the globular domain of H1 alone cannot induce chromatin folding, our results demonstrate that this function is primarily controlled by the COOH-terminal domain of the molecule. Surprisingly, these peptides do not locate correctly with respect to the nucleosome. This is demonstrated by their failure to confer upon reconstitutes the ability to protect DNA fragments of chromatosome length when digested with micrococcal nuclease. The precise placement of the H1 molecule (globular domain) with respect to the nucleosome is shown to be influenced by the "tail" domains of both H1 and the core histones.
J Mol Biol 1986 Feb 20
PMID:Roles of H1 domains in determining higher order chromatin structure and H1 location. 345 26

DNA isolated from 12 patients with childhood acute lymphoblastic leukaemia (T-ALL), analysed by gel electrophoresis exhibited a degradation pattern of increasing nucleosome repeat size, similar to that observed when nuclei from normal control cells are incubated with micrococcal nuclease. None of a group of adult T-ALL showed this fragmentation, nor was the pattern observed in normal control T-cells, cells from patients with a number of other forms of leukaemia, or in B-lymphoblastoid cells under the same incubation conditions. This phenomenon appears to be related to the changes in DNA that occur in glucocorticoid-induced cell death in mouse thymocytes, radiation-damaged spleen cells, and in cytotoxic T-cells deprived of interleukin 2. The method described here promises to be a reliable, simple approach to the characterization of T-ALL in childhood and may aid in the clinical management of this form of leukaemia.
Mol Biol Med 1987 Apr
PMID:DNA fragmentation in childhood T-cell acute lymphoblastic leukaemia. 349 10

A multicopy yeast plasmid containing the TRP1 gene (coding for N-5'-phosphoribosylanthranilate isomerase) and ARS1 (autonomously replicating sequence 1) has been purified as chromatin. Electrophoretic analysis of nucleic acid and proteins and electron microscopy show that the plasmid chromatin is largely free of contaminants. Electron-microscopic and linking-number analyses indicate that the plasmid chromatin contains seven nucleosomes, as predicted by the indirect end-label analyses of Thoma, Bergman, and Simpson [J. Mol. Biol. (1984) 177, 715-733]. Indirect end label mapping of micrococcal nuclease cuts demonstrates that nucleosome positions and nuclease-sensitive regions are not altered by the purification. The plasmid chromatin behaves homogeneously with respect to its elution from nuclei, template activity, and intrinsic buoyant density. Taken together, these observations suggest that different copies of the TRP1ARS1 plasmid do not differ from each other grossly in chromatin structure. We discuss the potential for understanding eukaryotic gene regulation offered by the ability to isolate unique genes as chromatin.
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PMID:Isolation of an episomal yeast gene and replication origin as chromatin. 353 6

A requisite step in the biosynthesis of tRNA is the removal of 5' leader sequences from tRNA precursors. We have detected an RNase P activity in yeast mitochondrial extracts that can carry out this reaction on a homologous precursor tRNA. This mitochondrial RNase P was sensitive to both micrococcal nuclease and protease, demonstrating that it requires both a nucleic acid and protein for activity. The presence of RNase P activity in vitro directly correlated with the presence of a locus on yeast mitochondrial DNA previously shown by genetic and biochemical studies to be required for tRNA maturation. The product of the locus, the 9S RNA, and this newly described mitochondrial RNase P activity cofractionated, providing further evidence that the 9S RNA is the RNA component of yeast mitochondrial RNase P.
Mol Cell Biol 1986 Apr
PMID:RNase P activity in the mitochondria of Saccharomyces cerevisiae depends on both mitochondrion and nucleus-encoded components. 353 97

We have reported the presence of insulin-related poly A+ RNA sequences in human placenta by RNA to DNA hybridization. In this study we have used a monoclonal antibody to somatomedin C/insulin-like growth factor I (Sm-C/IGF-I) to identify somatomedin-like proteins whose synthesis is directed by placental mRNA. Poly A+ RNA from first trimester and term placenta was translated in a cell-free system using micrococcal nuclease-treated reticulocyte-lysate and [35S]methionine as a label. From 2.0 X 10(6) cpm of specifically incorporated [35S]methionine labeled protein, an immunoprecipitate with an apparent molecular weight of 14,000 represented about 0.1% of total radioactivity in the translational products of poly A+ RNA of first trimester placenta. A less prominent band (0.006%) of the same apparent molecular weight was also evident from translational products of term placental mRNAs. This protein could be competed with either acromegalic serum or synthetic Sm-C/IGF-I when added prior to immunoprecipitation. Translational products synthesized from mRNA of term placenta showed a second labeled band of 24,000 daltons. This band was less effectively competed by acromegalic serum and not competed with either Sm-C/IGF-I or IGF-II and therefore its identity is uncertain. A protein similar to Sm-C/IGF-I is, therefore synthesized in first trimester placenta and to a lesser extent at term, suggesting developmental changes in Sm-C/IGF-I synthesis. Because Sm-C/IGF-I may act in a paracrine fashion, our findings suggest a role for Sm-C/IGF-I in growth of the placenta during early gestation.
Mol Biol Rep 1986
PMID:Synthesis of somatomedin C/insulin-like growth factor I by human placenta. 354 54

The contact points of transcription factor IIIA with the internal control region of the 5 S RNA gene of Xenopus have been investigated by probing the accessibility of the DNA in the protein-DNA complex to dimethylsulphate and to micrococcal nuclease. The results of quantitative measurements, combined with those from earlier DNase I and DNase II protection studies, are consistent with a series of multiple contacts about five base-pairs apart, or half a double-helical turn, along the whole length of the internal control region. The nine patches of contact we have mapped could correspond to nine DNA-binding fingers in the protein. A model for the overall geometry of the interaction is presented in which the protein lies on one face of the DNA double helix.
J Mol Biol 1986 Dec 05
PMID:Mapping of the sites of protection on a 5 S RNA gene by the Xenopus transcription factor IIIA. A model for the interaction. 356 Feb 27

The unfolding of nucleosome cores in transcriptionally active chromatin uncovers the sulfhydryl groups of histone H3, making them accessible to SH-reagents. This has suggested that nucleosomes from active genes could be retained selectively on organomercurial/agarose columns. When nucleosomes released from rat liver nuclei by limited digestion with micrococcal nuclease were passed through an Hg affinity column, a run-off fraction of compact, beaded nucleosomes was separated from a retained nucleosome fraction. Although both contained monomer-length DNA and a full complement of core histones, histones in the retained fraction were hyperacetylated. Dot blot hybridizations showed the Hg-bound nucleosome fraction to be enriched in DNA sequences transcribed by hepatocytes (serum albumin and transferrin genes), while a brain-specific gene (preproenkephalin) was not retained, but appeared in the nucleosomes of the run-off fraction. The results are discussed in light of other evidence linking hyperacetylation of histones H3 and H4 to conformational changes at the middle of the nucleosome core.
J Mol Biol 1987 Jul 20
PMID:Affinity chromatographic purification of nucleosomes containing transcriptionally active DNA sequences. 365 49

Histone octamers were reconstituted on plasmids carrying the alternating nucleotide sequence (G-C)15. The plasmids, radioactively labeled at one of two neighboring sites near the (G-C) insert, were digested with micrococcal nuclease. Nucleosome core particles were isolated and the monomer DNA subjected to restriction analysis. Quite different results are obtained if the reconstitution is carried out with relaxed plasmids, in which the (G-C) insert is in the B form, or with supercoiled plasmids, where it is in the Z form. With supercoiled plasmids, there is a marked reduction (compared with relaxed plasmids) in the abundance of labeled monomers, the result of a large decrease in core particles carrying any (G-C) sequence. Some core particles formed on supercoiled (Z) plasmids are positioned either just outside the (G-C) sequence, or with the sequence occupying the terminal position within the core particle. In contrast, monomers obtained from relaxed plasmids incorporate the (G-C) sequence in the B form more or less randomly in the interior of the core particle; species showing discrete positioning make only a minor contribution. We conclude that DNA in the Z form cannot be incorporated within core particles, except at their termini, and that a transition from the B to the Z form in vivo might result in a significantly altered local placement of nucleosomes.
J Mol Biol 1987 Aug 05
PMID:Effect of Z-DNA on nucleosome placement. 368 69


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