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)

Human globin messenger RNA was isolated from reticulocytes of four Jewish patients of Kurdish origin with homozygous beta0-thalassemia. On translation in the wheat-germ cell-free system, messenger RNA from these patients directed extensive synthesis of alpha- and gamma-globin chains, but synthesis of beta-globin chains was not detectable. In contrast, nonthalassemic human globin messenger RNA directed the synthesis of essentially equimolar amounts of alpha- and beta-globin. The patterns of globin synthesized by beta0-thalassemic messenger RNA in the cell-free system were virtually identical to the patterns of globin synthesized in peripheral blood cells of these patients. beta0-thalassemic messenger RNA similarly failed to direct any detectable beta-globin synthesis in a micrococcal nuclease-treated rabbit reticulocyte lysate, even in the presence of an excess of purified eukaryotic initiation factor 2. These results strongly suggest that functional messenger RNA for beta-globin chains is absent in Kurdish Jews with homozygous beta0-thalassemia.
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PMID:Absence of functional beta-globin messenger RNA in Kurdish Jews with beta0-thalassemia. 75 May 36

Proteins interacting with pre-mRNAs during early stages of spliceosome formation in a HeLa nuclear extract were investigated by photochemical RNA-protein crosslinking. The level of protein crosslinking to a beta-globin pre-mRNA was positively correlated with the presence of an intron. Proteins of 110,000, 59,000 and 39,000 mol. wt. were crosslinked to the beta-globin pre-mRNA, the latter of which was identified as the A1 hnRNP protein. Comparable experiments with an adenovirus pre-mRNA revealed crosslinked proteins of 110,000, 56,000 and 45,000 mol. wt., with the latter identified as belonging to the C group hnRNP proteins. Crosslinking of hnRNP proteins to both the beta-globin and adenovirus pre-mRNAs was eliminated by oligodeoxynucleotide-directed RNase H excision of an internal region (nt 28-42) of U2 RNA, but was not affected by oligo/RNase H cleavage of the 5'-terminal 15 nucleotides of U2 RNA. Cleavage of the 5'-terminal 15 nucleotides of U1 RNA preferentially eliminated crosslinking of the hnRNP A1 protein to both pre-mRNAs. The requirement of intact U1 snRNP for A1 protein crosslinking was further demonstrated by the fact that although micrococcal nuclease-treated extracts did not support crosslinking of A1 hnRNP protein to beta-globin pre-mRNA, crosslinking was restored by addition of a U1 snRNP-enriched fraction.
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PMID:Crosslinking of hnRNP proteins to pre-mRNA requires U1 and U2 snRNPs. 214

A component present in splicing extracts selectively binds the 3' splice site of a precursor messenger RNA (pre-mRNA) transcript of a human beta-globin gene. Since this component can be immunoprecipitated by either autoantibodies of the Sm class or antibodies specifically directed against trimethylguanosine, it is a small nuclear ribonucleoprotein (snRNP). Its interaction with the 3' splice site occurs rapidly even at 0 degrees C, does not require adenosine triphosphate, and is altered by certain mutations in the 3' splice site region. Binding is surprisingly insensitive to treatment of the extract with micrococcal nuclease. The U5 particle is the only abundant Sm snRNP with a capped 5' end that is equally resistant to micrococcal nuclease. This suggests that, in addition to the U1 and U2 snRNP's, U5 snRNP's participate in pre-mRNA splicing.
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PMID:The 3' splice site of pre-messenger RNA is recognized by a small nuclear ribonucleoprotein. 293 10

The structure of the chicken adult beta-globin gene chromatin in immature and mature erythrocyte nuclei has been analysed using micrococcal nuclease digestion. The resulting DNA fragments were blotted onto DBM-papers and probed with labelled DNA fragments spanning the adult beta-globin gene and its 5'- and 3'-flanking regions. The structure of the nucleosomes within and in the regions flanking the adult beta-globin gene appears to be altered in at least two ways in erythrocyte chromatin, when compared with either bulk or inactive ovalbumin gene chromatin. First, oligomeric DNA fragments containing the beta-globin gene are released faster than those of either bulk or ovalbumin gene chromatin. Second, although the difference in size of the liberated oligomeric DNA fragments is similar to the nucleosomal repeat length of bulk and ovalbumin gene chromatin, the individual oligomers are approximately 100 bp shorter than their bulk or ovalbumin gene counterparts, most noticeably when the nuclease digestion is performed at 37 degrees C. This results in an atypical ladder of approximately 300, 500, 700, 900 bp instead of the canonical chicken erythrocyte ladder which is an integral multiple of 207 bp. The same ladder was obtained from immature erythrocytes, in which the beta-globin gene is actively transcribed, and from mature erythrocytes, in which it is considered to be inactive with RNA polymerase molecules clustered in the 5' moiety of the gene. This indicates that the alteration of the nucleosomal structure is not due to transcription per se.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Digestion of the chicken beta-globin gene chromatin with micrococcal nuclease reveals the presence of an altered nucleosomal array characterized by an atypical ladder of DNA fragments. 301

We examined the relationship between pre-mRNA splicing and the nuclear matrix by using an in vivo system that we have developed. Plasmids containing the inducible herpesvirus tk gene promoter linked to an intron-containing segment of the rabbit beta-globin gene were transfected into HeLa cells, and then the promoter was transactivated by infection with a TK- virus. Northern analysis revealed that the globin pre-mRNA and all its splicing intermediates and products are associated with the nuclear matrix prepared from such transfected cells. When the nuclear matrix was incubated with a HeLa cell in vitro splicing extract in the presence of ATP, the amount of matrix-associated precursor progressively decreased without a temporal lag in the reaction, with a corresponding increase in free intron lariat. Thus, most of the events of the splicing process (endonucleolytic cuts and branching) occur in this in vitro complementation reaction. However, ligation of exons cannot be monitored in this system because of the abundance of preexisting mature mRNA. Since the matrix is not a self-splicing entity, whereas the in vitro splicing system cannot process efficiently deproteinized matrix RNA, we conclude from our in vitro complementation results (which can be reproduced by using micrococcal nuclease-treated splicing extract) that the nuclear matrix preparation retains parts of preassembled ribonucleoprotein complexes that have the potential to function when supplemented with soluble factors (presumably other than most of the small nuclear ribonucleoproteins known to participate in splicing) present in the HeLa cell extract.
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PMID:Pre-mRNA splicing and the nuclear matrix. 303 50

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

The organization of nucleosomes associated with a cell cycle regulated human H4 histone gene was examined in synchronized HeLa S3 cells. At various times during the cell cycle, nuclei were digested with micrococcal nuclease, and the nucleosomal pattern of the gene was obtained by Southern blot analysis using radiolabeled human histone H4 gene probes. We have detected reversible changes during the cell cycle in the chromatin structure of this gene, as reflected by the shortening of the nucleosomal spacing after replication and the peak of transcription. This variation is also observed when DNA and protein syntheses are inhibited. By using a probe that comprises 250 base pairs (bp) of the coding region and 240 bp of the 5' end of the gene, containing the promoter and DNase I sensitive sequences, we also have observed a general disruption of the nucleosomal organization, which is reflected by a degeneration of the characteristic nucleosomal ladder produced by micrococcal nuclease digestion. This modification coincides with the replication and active transcription of the gene (early S phase), which recovers its regular nucleosomal appearance when both processes have been completed, although the nucleosome linker length is shortened. When the probe utilized comprises the distal 3' end of the gene, there is no disruption of the nucleosomal pattern, but the linker region also exhibits a shortened length. A non-cell cycle regulated gene (beta-globin) does not exhibit such modifications in any of the situations analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Reversible changes in the nucleosomal organization of a human H4 histone gene during the cell cycle. 377 65

We [Rocha, E., Davie, J.R., van Holde, K.E., & Weintraub, H. (1984) J. Biol. Chem. 259, 8558-8563] have previously reported that the transcriptionally competent beta-globin gene domain is selectively enriched in chromatin fractions eluted with solutions of approximately physiological ionic strength from micrococcal nuclease digested mature chicken erythrocyte nuclei. In this report, we demonstrate that beta-globin chromatin is eluted as oligonucleosomes while vitellogenin, a transcriptionally inactive gene, is eluted as mononucleosomes as is the bulk of sequences found in this fraction. Following removal of the salt, the eluted chromatin was made 100 mM KCl and separated into aggregation-prone and aggregation-resistant fractions. Globin sequences were present in both fractions and had the greatest enrichment in the aggregation-prone fraction which contained H1 and H5, H1 being more abundant. A procedure is presented in which H1 is selectively removed from the erythrocyte nuclei. Following the selective removal of H1 and subsequent fractionation, globin but not vitellogenin oligonucleosomes were present in the aggregation-resistant chromatin fraction. The results indicate the beta-globin domain is a mosaic of aggregation-resistant and aggregation-prone regions with the latter being associated with H1 and H5. Vitellogenin sequences were associated principally with aggregation-prone regions complexed with H5.
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PMID:Selective solubilization of beta-globin oligonucleosomes at low ionic strength. 382 4

During differentiation of murine erythroleukemia cells, adult beta-globin gene chromatin acquires site-specific, DNase I hypersensitivity and an increased sensitivity in the globin gene region toward micrococcal nuclease (MNase) digestion. The relationship of these changes in chromatin structure to globin gene activation and to cellular commitment events has been studied. Imidazole, which blocks globin gene transcription during induction does not affect the terminal differentiation of the cells nor does it prevent the acquisition of DNAse I hypersensitivity. The formation of the inducible DNase I-hypersensitive site near the globin gene accompanies the developmental events which lead to cellular differentiation independent of the transcription process. The increased MNase sensitivity of the adult beta-globin gene region, normally preceded by the acquisition of 5' DNase I hypersensitivity, was blocked by the addition of imidazole prior to but not after globin gene activation. The enhanced MNase sensitivity was not abolished by the addition of actinomycin D and, thus, reflects a part of chromatin alterations that define potential for transcription. Therefore, there is a sequential series of chromatin alterations in the globin gene region associated with murine erythroleukemia cell differentiation. The appearance of the inducible 5' DNase I-hypersensitive site precedes the onset of globin gene transcription and is strongly correlated with commitment events. The enhanced MNase sensitivity is closely related to globin gene transcription, but it is not a consequence of the transcription process. In addition, the commitment of cells to terminal differentiation is dissociable from the stimulation of globin gene transcription.
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PMID:Sequential alterations in globin gene chromatin structure during erythroleukemia cell differentiation. 385 50

A nuclear extract from HeLa cells has been separated by DEAE-cellulose chromatography into two fractions, both of which are required for mRNA splicing in vitro. Both fractions are heat labile and sensitive to N-ethylmaleimide. The activity of one of the fractions was abolished by preincubation with micrococcal nuclease, while the other fraction was unaffected by this treatment. This abolition indicates an essential nucleic acid component. Fractions I and II are required for the in vitro splicing of human beta-globin and adenovirus transcripts.
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PMID:Isolation and characterization of two fractions from HeLa cells required for mRNA splicing in vitro. 385 67


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