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)

The influence of cis-diamminedichloroplatinum (II) (cis-DDP) binding to chromatin in chicken erythrocyte nuclei and the nucleosomal core particle is investigated. The cis-DDP modifications alter DNA-protein interactions associated with the higher order structure of chromatin to significantly inhibit the rate of micrococcal nuclease digestion and alter the digestion profile. However, cis-DDP modification of core particle has little effect on the digestion rate and the relative distribution of DNA fragments produced by microccocal nuclease digestion. Analysis of the monomer DNA fragments derived from the digestion of modified nuclei suggests that cis-DDP binding does not significantly disrupt the DNA structure within the core particle, with its major influence being on the internucleosomal DNA. Together these findings suggest that cis-DDP may preferentially bind to the internucleosomal region and/or that the formation of the intrastrand cross-link involving adjacent guanines exhibits a preference for the linker region. Sucrose gradient profiles of the modified nucleoprotein complexes further confirm that the digestion profile for micrococcal nuclease is altered by cis-DDP binding and that the greatest changes occur at the initial stages of digestion. The covalent cross-links within bulk chromatin fix a sub-population of subnucleosomal and nucleosomal products, which are released only after reversal by NaCN treatment. Coupled with our previous findings, it appears that this cis-DDP mediated cross-linking network is primarily associated with protein-protein crosslinks of the low mobility group (LMG) proteins.
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PMID:cis-diamminedichloroplatinum (II) modified chromatin and nucleosomal core particle. 185 41

Chicken erythrocyte chromatin was depleted of histones H1, H5, H2A and H2B. The resulting (H3/H4)-containing chromatin was digested with micrococcal nuclease to yield monomer, dimer, trimer etc. units, irregularly spaced on the DNA, with even-number multimers being more prominent. Sucrose density gradient centrifugation separated monomers and dimers (7.7 S and 10.5 S). Sodium dodecyl sulphate gel electrophoresis and cross-linking indicated: the monomer contains 50-base-pair (bp), 60-bp and 70-bp DNA and the dimer 125-bp DNA; the monomer contains a tetramer and the dimer an octamer of H3 and H4. Partial association of monomer units to dimers inhibits structural studies of monomers. The internal structure of the dimer, i.e. and (H3/H4)4-125-bp-DNA particle, was studied using circular dichroism, thermal denaturation and nuclease digestion. Both micrococcal nuclease and DNase I digestion indicate that, unlike core particles, accessible sites occur in the centre of the particle and it is concluded that the (H3/H4)4-125-bp-DNA particle is not a 'pseudo-core particle' in which the 'extra' H3 and H4 replace H2A and H2B. It is proposed that the octamer particle is formed by the sliding together of two 'monomer' units, each containing the (H3/H4)2 tetramer and 70 bp of DNA. Excision of this dimer unit with micrococcal nuclease results in the loss of 10 readily digestible base pairs at each end, leaving 125 bp.
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PMID:The structure of sub-nucleosomal particles. The octameric (H3/H4)4--125-base-pair-DNA complex. 404 75

The nuclear distribution of Drosophila DNA topoisomerase II was determined by immunoblot analysis after nuclease digestion and cell fractionation. About 60% of DNA topoisomerase II could be removed from nuclei by RNase A, about 70% by DNase I, and about 90% by incubation with both enzymes together or with micrococcal nuclease. Nuclease treatment of nuclei did not affect the distribution of lamins Dm1 and Dm2 or other nuclear proteins similarly. Nuclease-mediated solubilization of DNA topoisomerase II from Drosophila nuclei was also dependent on NaCl concentration. Solubilization was not efficient below 100 mM NaCl. Sucrose velocity gradient ultracentrifugation demonstrated that DNA topoisomerase II solubilized from nuclei by either RNase A or DNase I migrated at about 9 S, as expected for the homodimer. Results of chemical crosslinking supported this observation. We conclude that DNA topoisomerase II has both RNA- and DNA-dependent anchorages in Drosophila embryo nuclei.
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PMID:Nuclear distribution of Drosophila DNA topoisomerase II is sensitive to both RNase and DNase. 761 83

In cell-free translations of RNA from primary cultures of pig trachea surface epithelial cells we observed that a mRNA encoding a 20 kDa proline-rich protein (sPRP) was dramatically induced during culturing (Tesfaigzi et al., 1990, Biochem. Biophys. Res. Commun., 172:M1304-1309). This mRNA was not detected in tracheal tissue or in epithelial cells prior to culturing. Antisera were raised to synthetic peptide sequences corresponding to 23 amino acids on the C-terminus (C23-antiserum) and 29 amino acids on the N-terminus (N29 antiserum) of sPRP. On Western blot analysis, C23 antiserum reacted with a 20 kDa protein in cytosolic extracts from pig tracheal cells maintained in culture for 4 days. The reaction with the 20 kDa protein was inhibited by adding C23 peptide. Two nuclear proteins (66 and 70 kDa) obtained by micrococcal nuclease treatment of tracheal cell nuclei were detected on Western blots with C23 antiserum. These proteins were present in cells both before and after culturing. Sucrose gradient fractionation indicated that these nuclear proteins are associated with chromatin. Small amounts of the 66 and 70 kDa proteins were obtained from nuclear matrix fractions. These nuclear proteins also reacted with N29 antiserum. Since these proteins share similar epitopes with the N- and C-termini of sPRP, it is likely that the 20 kDa protein (sPRP) is part of these proteins. However, purification of the nuclear proteins followed by an amino acid sequence analysis is necessary to clarify whether sPRP is part of these proteins.
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PMID:Two nuclear proteins in tracheal epithelial cells are recognized by antibodies specific to a squamous differentiation marker, sprI. 765 64

Replication protein A (RPA) is the major single strand-specific DNA-binding protein in eukaryotic cells. We have investigated the distribution of RPA in nuclei of proliferating HeLa cells and found that only one-third of the detectable RPA appeared to be bound to DNA in chromatin, whereas the remainder was free in the nucleosol. This distribution did not significantly change when cells were released from a double thymidine block into the S phase of the cell cycle. Single strand-specific endonucleases failed to mobilize RPA bound to chromatin in G1 phase and S phase HeLa cells. In contrast, brief treatments with pancreatic DNase I or with micrococcal nuclease sufficed to release RPA from its chromatin-binding sites. Sucrose gradient analysis of soluble micrococcal nuclease digests showed that the released RPA sedimented free of mono- or oligonucleosomal chromatin fragments, possibly indicating that most of the detectable RPA may be associated with chromatin sites, which are more open to nuclease attack than bulk chromatin. The surprising conclusion is that the majority of the detectable RPA is, either directly or indirectly, associated with double-stranded DNA regions in chromatin from HeLa cells in G1 phase and in S phase.
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PMID:Chromatin association of replication protein A. 982 37