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

---

Query: EC:3.1.21.1 (DNase)
7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reversible cross-linking of proteins in nuclei and DNA-depleted nuclei from Friend erythroleukemia cells was used as a probe to determine whether the protein structure was preserved following treatment with DNAase I. Interactions between histones were analyzed through cross-linking with 2-iminothiolane or dimethyl 3,3'-dithiobispropionimidate. No alterations in the interactions between intranucleosomal histone proteins resulted from digestion of the nuclear DNA. There was, however, a diminished extent of cross-linking of histone H1 to itself and to the intranucleosomal histones in DNA-depleted nuclei. The interactions of a group of nonhistone proteins with histone H3 could be monitored by cross-linking through the formation of disulfide bonds caused by oxidation of nuclei with H2O2. These interactions were not markedly affected by treatment of the nuclei with DNAase I. However, differences were observed in the extent of cross-linking of some of these proteins when cross-linking in nuclei from undifferentiated cells was compared to that in nuclei from cells which had been induced to differentiate with dimethylsulfoxide.
...
PMID:Cross-linking of proteins in nuclei and DNA-depleted nuclei from Friend erythroleukemia cells. 29 21

The structure of chicken erythrocyte and chicken liver chromatin has been studied by enzymatic digestion with micrococcal nuclease and DNAase I. Comparison of the fragments produced by brief digestion with micrococcal nuclease indicates that chicken erythrocyte chromatin has a longer nucleosome repeat than chicken liver chromatin, 212 base pairs as opposed to 200 base pairs (bp). More extensive digestion with micrococcal nuclease demonstrates that both tissues have 140 bp mucleosome cores. The difference in the length of the nucleosome repeat must therefore result from a difference in the length of the DNA linker between cores. Chicken erythrocyte chromatin is known to contain a tissue-specific, H1-like histone, H5, and to be genetically dormant. A model is presented to explain how changes in histone H1 could cause changes in the nucleosome repeat length and thereby alter the genetic activity of chromatin.
...
PMID:A comparison of the structure of chicken erythrocyte and chicken liver chromatin. 100 80

Recent evidence indicates that chromatin accessibility to transcription factors is of regulatory significance. The polyanion heparin is known to increase chromatin accessibility to DNAase I and to stimulate both RNA and DNA synthesis. In the present study, chromatin structure and its modification by polyanions were examined by using trypsin and micrococcal nuclease as probes. Both heparin and poly(glutamic acid) were found to be equivalent to trypsin digestion of histones in their ability to increase nuclease accessibility in chromatin. However, no increase in nuclease accessibility was observed when trypsin-digested chromatin was further treated with heparin, indicating that polyanions and trypsin are not additive in their effects on chromatin accessibility. Moreover, sucrose-gradient analysis demonstrated that heparin binds tightly to intact nucleosomes but not to trypsin-digested nucleosomes. These data suggest that polyanions interact predominantly with the trypsin-sensitive lysine and arginine residues in histone H1 and the N-terminal segments of the core histones. The possible relevance of these results to the chromatin structure of actively transcribed regions is discussed.
...
PMID:Heparin increases chromatin accessibility by binding the trypsin-sensitive basic residues in histones. 128 84

We investigated the effect of various forms of DNA (double- and single-stranded calf thymus DNA, circular plasmid DNA, gamma- and UV-irradiated DNA and DNAase I-treated double-stranded DNA) aggregated with histones, on the proteolysis of these histones by proteinase associated with the rat liver nuclear scaffold. It was shown that the nuclear scaffold-associated proteinase is able to degrade selectively the histone H1 only in the presence of the DNA containing single-strand breaks induced by gamma-radiation or DNAase I treatment as well as in the presence of heat-denatured DNA. This proteinase is not activated by the double-stranded circular plasmid DNA or by UV-treated double-stranded DNA. Histone H1-specific proteinase (HSP) activated by gamma-irradiated DNA is inhibited by inhibitors of serine proteinases such as antipain, leupeptin, phenylmethylsulphonyl fluoride, as well as by dithiothreitol. The results lead us to suggest that DNA-activated HSP from rat liver nuclei is involved in the regulation of the access of repair enzymes to the damage portions of DNA within chromatin.
...
PMID:Gamma-irradiated DNA activates histone H1-specific proteinase of rat liver nuclei. 135 3

Two DNA endonuclease complexes have been isolated from the chromatin of normal human and xeroderma pigmentosum, complementation group A (XPA), lymphoblastoid cells which are active on DNA damaged with psoralen plus long wavelength ultraviolet radiation (UVA). In both normal and XPA cells, one endonuclease complex, pI 4.6, recognizes the psoralen cross-link and the other endonuclease complex, pI 7.6, recognizes the psoralen monoadduct. The levels of activity of these complexes from both normal and XPA cells are similar on damaged naked DNA. Kinetic analysis of assays using graduated concentrations of substrate revealed that selective activity of these endonuclease complexes on 8-MOP plus UVA treated DNA correlates with a reduction in Km of these complexes, indicating an increased affinity for, or rate of association with, damaged naked DNA. When the damaged substrates were reconstituted into core nucleosomes (without histone H1), both normal endonuclease complexes showed a 2.5-fold enhancement of activity, which correlated kinetically with a further increase in affinity, or rate of association (decreased Km), for this damaged nucleosomal substrate. This increase in activity and in affinity was reduced but not eliminated when histone H1 was present. By contrast, neither XPA endonuclease complex showed this enhanced activity on, or affinity for, damaged core nucleosomal DNA, and actually showed decreased activity, and affinity, when histone H1 was present. Introduction, via electroporation, of either of the normal complexes into 8-MOP plus UVA treated XPA cells in culture corrected their DNA-repair defect, further confirming the role of these complexes in the repair process.
...
PMID:Xeroderma pigmentosum endonuclease complexes show reduced activity on and affinity for psoralen cross-linked nucleosomal DNA. 137 99

The influence of nucleosomes on the activity of two chromatin-associated apurinic/apyrimidinic (AP) DNA endonuclease activities, pIs 9.2 and 9.8, from normal and xeroderma pigmentosum, complementation group A (XPA), lymphoblastoid cells was examined. These AP endonuclease activities were studied on non-nucleosomal and nucleosomal plasmid pWT830/pBR322 DNA which had been reconstituted with core (H2A, H2B, H3, H4) or total (core plus H1) histones from normal or XPA cells. Both nucleosomal and non-nucleosomal DNA was rendered partially AP by alkylation with 12.5 mM methyl methanesulfonate, followed by heating it at 70 degrees C, to produce approximately three AP sites per DNA molecule. The activities of both normal lymphoblastoid AP endonuclease activities on nucleosomal AP DNA, reconstituted with core histones, was approximately 2.5 times greater than that on non-nucleosomal AP DNA. When histone H1 was added to the system, this increase was reduced. XPA AP endonuclease activities, on the other hand, did not show any increase in activity on nucleosomal AP DNA reconstituted with core histones. These differences between normal and XPA endonuclease activities on AP nucleosomal DNA were the same regardless of whether histones from normal or XPA cells were used in the reconstituted system.
...
PMID:Enhancement of two apurinic/apyrimidinic endonuclease activities from normal but not xeroderma pigmentosum lymphoblastoid cells by nucleosome structure. 242 53

The levels and distribution between nucleus and cytoplasm of HMG1 and HMG2 proteins have been investigated in different tissues of mammals. In lymphoid tissues and testis high amounts of these proteins are present in both nuclei and cytoplasm, while in the hepatic tissues and brain they accumulate in cytoplasm, mainly in the cytosol. In particular, very low amounts, if any, of HMG1 and 2 are present in the nuclei active for DNA replication (rat regenerating liver and primary hepatoma) or transcription (adult liver and brain). Therefore, it appears that HMG1 and 2 are not necessary for these processes. On the other hand, nuclear (chromosomal) HMG1 and 2 are characteristic for the tissues containing undifferentiated cells: lymphoid tissues, testis, neonatal liver. These proteins are bound to the chromatin regions solubilized early by sonication or DNase action. Comparison of the data obtained for different tissues shows an inverse correlation between the amounts of chromosomal HMG1 and 2, on the one hand, and of histone H1(0), on the other hand. These results suggest that chromosomal HMG1 and 2 take part in the processes that occur during cell differentiation, while histone H1(0) is induced to preserve differentiated cells from dedifferentiation.
...
PMID:Tissue specificity of nucleo-cytoplasmic distribution of HMG1 and HMG2 proteins and their probable functions. 258 85

The granular particles of chromatin peripheral layer, were isolated together, with the nuclear envelope by treatment of nuclei with nuclease. These particles differ from total chromatin by a decreased content of histone H1, a specific set of minor acid-soluble proteins and a low DNA methylation level. Taking account of the fact that these particles facilitate chromatin interaction with the nuclear envelope, the latter were termed as "anchorosomes". Using UV-induced cross-linking of DNA to the proteins, it was found that all anchorosome-specific acid-soluble proteins can directly interact with anchorosomal DNA. Treatment of anchorosomes with staphylococcal nuclease and electron microscopic data showed that anchorosomes have a nucleosomal organization. Five to ten per cent of anchorosomal DNA appear to be firmly bound to nuclear lamina. This DNA cannot be separated from the lamina by treatment with 2 M NaCl, 1% SDS or heparin (1 mg/ml). The bulk of DNA in the laminal fraction after treatment with the above reagents is protected from hydrolysis with DNAase I by anchorosomal proteins and thus has a high molecular weight (10,000-30,000 base pairs). After treatment of anchorosomes with 0.6 M or 2 M NaCl, DNAase I splits this DNA, predominantly to minor fragments.
...
PMID:[Study of peripheral chromatin granules--anchorosomes]. 262 53

Peripheral chromatin granules bound to the nuclear envelope of rat liver nuclei have been further investigated. Judging by the results of Staphylococcal nuclease digestion of nuclei and electron microscopical observations, the peripheral granules have nucleosomal organization. As shown by ultraviolet radiation DNA-protein cross-linkage, the histone-like proteins present in the peripheral chromatin instead of histone H1 (Fais et al., 1982) are in close contact with DNA. The peripheral chromatin contains a DNA firmly bound to the lamina. This DNA, resistant to extraction in high salt, heparin and SDS, is protected against a DNase attack since, as shown by DNA electrophoresis data, high molecular weight molecules (up to 20 kbas) are still present in the lamina residue. However, the high molecular weight DNA disappeared if the nuclear envelope fraction was again DNase-digested after high salt treatment. Altogether, the data of the previous (Fais et al., 1982; Prusov et al., 1980: Prusov et al., 1982) and the present investigations demonstrate that the peripheral chromatin granules are endowed with properties which distinguish them from the bulk chromatin and account for the chromosome bond to the nuclear envelope during interphase. This is why we suggest the term "anchorosome" for the peripheral protein granule attached to the nuclear envelope.
...
PMID:The anchorosome, a special chromatin granule for the anchorage of the interphase chromosome to the nuclear envelope. 280 85

Light treatment of nuclei of Physarum polycephalum microplasmodia with DNase I, at low MgCl2 concentration (less than or equal to 3% DNA acid solubility, 0.1 mM MgCl2) selectively solubilizes a defined fraction of chromatin, in the form of a macromolecular complex. This fraction (up to 15% of the total chromatin) contains a full complement of the core histones and a reduced amount of histone H1, and is enriched in the high-mobility-group type of proteins. It is preferentially associated with nascent RNA and RNA polymerase B actively engaged in transcription. Digestion of DNAase-I-solubilized chromatin by micrococcal nuclease releases a size-heterogeneous population of cleavage products, indicative of lack of a typical nucleosomal packaging. It is concluded that the procedure used allows the isolation of structurally and functionally distinct regions of Physarum chromatin.
...
PMID:Lack of nucleosomal structure in a DNase-I-solubilized transcriptionally active chromatin fraction of Physarum polycephalum. 397 88


1 2 3 Next >>

---