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)

Bleomycin (BLM) exclusively affects thymidine-containing compounds such as DNA and polydeoxyribonucleotides by releasing free thymine and leaving aldehyde functions. Molecular morphology and base sequence of the DNA strongly influence BLM activity. High BLM concentrations, besides modifying DNA into oligothyminic or athyminic nucleic acids, cause strand scissions. Enzymatic DNA and RNA synthesis is strongly influenced by BLM. The inhibition in DNA-dependent DNA polymerase and DNA-dependent RNA polymerase assays is of the non-competitive type. Protein biosynthesis in in vitro systems is not affected by BLM even at high concentrations. BLM turns out to be a strong inhibitor of DNase I and of DNase II; the inhibition is of the competitive type. The enzymatic activities of nucleases using RNA as substrate (RNase A, RNase B, Rnase T1, venom phosphodiesterase I and spleen phosphodiesterase II) are not influenced by this antibiotic. The antibiotic reduces cell proliferation (L5178y mouse lymphoma cells) in vitro in low concentrations by cytostasis and at higher concentrations by cytotoxicity. In BLM-treated L5178y cells, DNA synthesis is strongly reduced, while RNA and protein synthesis are not affected. In vivo, using growing quail oviducts, cell proliferation and cytodifferentiation are markedly inhibited after BLM treatment. This is attributed to the observed inhibition of DNA synthesis. RNA and protein synthesis as well as gene expression are not influenced by BLM under the conditions used. The selective inhibition of DNA synthesis in vivo may be caused by the following mechanisms: (1) competition of BLM with RNA; (2) blocking of the accessibility of DNA in chromatin to BLM, and (3) dependence from the repair processes. BLM inhibits growth of sarcomas, induced by oncogenic RNA viruses in vivo; well-developed tumours show regression after BLM treatment. Transformation of chick embryo fibroblasts by oncogenic RNA viruses in vitro and growth of these viruses is blocked by BLM; the most sensitive period for BLM inhibition is the time during the first period (integration of viral genome into cellular genome?) after infection.
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PMID:Effect of bleomycin on DNA, RNA, protein, chromatin and on cell transformation by oncogenic RNA viruses. 6 69

The sequence of 129 nucleotides next to the poly(A) tail of encephalomyocarditis virus RNA has been determined by rapid gel sequencing of cDNA synthesized with DNA polymerase I or reverse transcriptase and a phasing primer, [5'-32P]p(dT)8dC. The sequence is in accord with (a) the pyrimidine tracts which were mapped in blocks along the cDNA, (B) the sequences of seven characteristic T1 RNase oligonucleotides in the RNA transcribed from the cDNA with RNA polymerase, and (c) a limited amount of sequence deduced by partial spleen phosphodiesterase digestion and depurination of endonuclease IV oligonucleotides. The 3' end shows little secondary structure on its own. Ten nonsense codons block all three reading frames such that at least 26 nucleotides do not code for protein. The possible function of a homology A-A-U-A-A-A with other polyadenylated RNAs is discussed.
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PMID:Sequence of 129 nucleotides at the 3'-terminus of encephalomyocarditis virus RNA. 7 85

The infectivity of replicative form RNA (RF-RNA) isolated from poliovirus-infected HeLa cells is completely resistant to the action of T-1 RNase but decreases after exposure to RNase A in the presence of 0.3 M NaCl. Under these conditions neither enzyme produces single-stranded nicks in RF-RNA. Three endonuclease-free exonuleases (RNase II, polynucleotide phosphorylase and spleen phosphodiesterase) rapidly destroy the infectivity of single-stranded RNA, but do not alter the infectivity of RF-RNA. It is concluded that RF-RNA does not contain single-stranded ends essential for infectivity. Indirect evidence suggests that all or most of the poly A region at the 3' end of the plus strand of infectious RF-RNA is base-paired to a poly U region at the 5 end of the minus strand.
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PMID:Poliovirus-induced infectious double-stranded RNA: Effect of RNA-degrading enzymes. 16 28

A spermidine-dependent endoribonuclease (designated as RNase 65) activity requires both RNA and protein components (Nashimoto et al. (1991) Biochem. Biophs. Res. Comm. 176:1163-1169). In this study, we fractionated RNAs from mouse FM3A cell extracts and showed that an RNA fraction containing two major RNAs and two minor ones restored the micrococcal nuclease-inhibited RNase 65 activity. Partial sequences of these four RNA species were determined by chemical RNA sequencing. A sequence homology search revealed that the two major RNAs were glutamine tRNA lacking its 3' terminus, and that the two minor RNAs were initiator methionine tRNA and glycine tRNA lacking their 3' termini.
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PMID:Transfer RNA lacking its 3' terminus is required for spermidine-dependent ribonuclease 65 activity in mouse FM3A cell extracts. 187 44

A cell-free system for the study of transcription of African swine fever virus (ASFV) mRNA was developed from cytoplasmic extracts of infected cells permeabilized with lysolecithin. Extracts prepared from infected cells early and late after infection incorporated [alpha-32P]UTP into acid-insoluble material that was resistant to DNase and sensitive to RNase. The incorporation was inhibited by actinomycin D but not by alpha-amanitin. The presence of the nuclei was not required. In vitro transcription was optimal at pH 7.9 and at concentrations of 100 mM NH4Cl, 5 mM magnesium acetate, and 250 microM MnCl2. Early infected cell extracts transcribed from endogenous viral DNA a set of RNAs similar in electrophoretic migration to that observed in intact infected cells. Late infected cell extracts seemed to be unable to transcribe new RNA species besides those transcribed early after infection. The activity of the extracts could be made dependent on exogenous templates by digestion with micrococcal nuclease. RNAs transcribed after addition of native or denatured viral DNA to nuclease-treated extracts were indistinguishable from those transcribed from endogenous viral DNA. Late infected cell extracts digested with micrococcal nuclease were also active in transcribing virus-specific RNA from p2SB21, a recombinant plasmid containing the SalI B fragment of ASFV DNA.
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PMID:In vitro transcription by cytoplasmic extracts from cells infected with African swine fever virus. 259 35

The turnover rates of some mRNAs vary by an order of magnitude or more when cells change their growth pattern or differentiate. To identify regulatory factors that might be responsible for this variability, we investigated how cytosolic fractions affect mRNA decay in an in vitro system. A 130,000 X g supernatant (S130) from the cytosol of exponentially growing erythroleukemia cells contains a destabilizer that accelerates the decay of polysome-bound c-myc mRNA by eightfold or more compared with reactions lacking S130. The destabilizer is deficient in or absent from the S130 of cycloheximide-treated cells, indicating that it is labile or is repressed when translation is blocked. It is not a generic RNase, because it does not affect the turnover of delta-globin, gamma-globin, or histone mRNA and does not destabilize a major portion of polysomal polyadenylated mRNA. The destabilizer accelerates the turnover of the c-myc mRNA 3' region, as well as subsequent 3'-to-5' degradation of the mRNA body. It is inactivated in vitro by mild heating and by micrococcal nuclease, suggesting that it contains a nucleic acid component. c-myb mRNA is also destabilized in S130-supplemented in vitro reactions. These results imply that the stability of some mRNAs is regulated by cytosolic factors that are not associated with polysomes.
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PMID:Regulation of c-myc mRNA stability in vitro by a labile destabilizer with an essential nucleic acid component. 274 42

Model transcripts containing mammalian pre-rRNA sequences were incubated with a HeLa cell extract, digested with T1 RNase, and immunoprecipitated with anti-(U3)RNP or control antibodies. Two overlapping fragments derived from the 3' domain of human 28S rRNA were specifically immunoprecipitated although transcripts which spanned the transcription initiation site, the ETS processing site, the 5' end of 18S, and both termini of 5.8S yielded no protected fragments. The sequence of these fragments was determined using a novel technique in which the [32P]-labeled fragment was co-finger-printed with [3H]-labeled total transcript serving as an internal marker. The fragments immunoprecipitated derive from nucleotides 4570-4590 and 4575-4590 of human 28S and are adjacent to the alpha-sarcin site. Protection most likely involves the U3 RNA since it is sensitive to pretreatment of the extract with micrococcal nuclease. Complementarity between U3 and this rRNA region is phylogenetically conserved in species ranging from human to S. cerevisiae. The possible significance of this finding is discussed.
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PMID:An in vitro interaction between the human U3 snRNP and 28S rRNA sequences near the alpha-sarcin site. 297 35

Retinol (vitamin A alcohol), which plays an important role in the differentiation of epithelia, can be transferred to chromatin in vitro. Rat liver chromatin can accept retinol in a specific and saturable manner only when the retinol is presented as a complex with cellular retinol-binding protein (CRBP). A partial characterization of the nuclear components responsible for accepting retinol is reported here. A preparation of solubilized chromatin isolated from liver nuclei was able to accept retinol from its complex with CRBP as described previously for nuclei and chromatin. The binding of retinol to chromatin was noncovalent. However, chromatin prepared from nuclei which were incubated with DNase I or micrococcal nuclease did not accept retinol specifically. Chromatin in the form of mono and dinucleosomes also did not accept retinol. However, treatment of nuclei with RNase did not affect the specific binding of retinol. Furthermore, it has been found that retinol was not transferred to purified double or single stranded DNA. These results are interpreted to indicate that the transfer of retinol to specific nuclear binding sites requires a higher order of chromatin structure than that occurring in nucleosome preparations.
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PMID:Partial characterization of nuclear binding sites for retinol delivered by cellular retinol binding protein. 298 10

With the use of a reconstituted poly(ADP-ribosyl)ating enzyme system and three purified nucleases, micrococcal nuclease (MN), bull seminal RNase (BS RNase) and Ca2+, Mg2+-dependent endonuclease (BS DNase), as model acceptor proteins for ADP-ribose, the effect of ionic strength on the modification reaction was examined in detail. When these three nucleases were extensively poly(ADP-ribosyl)ated in this system at a low ionic strength (5 mM Tris), they were all inhibited by about 80% and the chain length of the polymer covalently bound to the nucleases was 13 to 23 ADP-ribose units. The observed inhibition was markedly prevented by increasing the ionic strength in the reaction mixture with a concomitant decrease in the polymer size bound to the nucleases. The NaCl concentrations required for decreasing the extent of the inhibition to half of the maximum were calculated to be 20, 50, and 100 mM for MN, BS RNase, and BS DNase, respectively. These values are similar to the NaCl concentrations required for decreasing the average chain lengths of the polymer to half, suggesting that the length of polymer is closely correlated to the extent of inhibition of these nucleases. DNA-binding affinities of these nucleases, expressed in terms of the NaCl concentrations required for eluting the enzymes from DNA-cellulose, were 140, 280, and 340 mM for MN, BS RNase, and BS DNase, respectively. Considering that maintainance of a ternary complex of poly(ADP-ribose) synthetase, acceptor and DNA may be essential for the modification reaction, the relatively strong salt effect observed in the modification of MN may be explained by its low DNA-binding affinity.
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PMID:Effect of ionic strength on chain elongation in ADP-ribosylation of various nucleases. 371 Oct 53

A new method to determine oligo- and poly(ADP-ribosyl)ated enzymes and proteins in vitro has been developed. This method is based on the facts that in Mg2+-depleted condition automodification of poly(ADP-ribose)polymerase is minimized and exogenously added acceptor protein is oligo(ADP-ribosyl)ated predominantly, and in Mg2+-fortified conditions the exogenous acceptor can be poly(ADP-ribosyl)ated. When 13 proteins, including several enzymes, were subjected to this system, dimeric bovine seminal RNase and micrococcal nuclease were found to be oligo(ADP-ribosyl)ated under Mg2+-depleted conditions but their activity was unchanged. Under Mg2+-fortified conditions however, the RNase was deactivated concomitantly with its extensive poly(ADP-ribosyl)ation. When dimeric bovine seminal RNase was monomerized in advance by treatment with dithiothreitol and urea, the enzyme lost ADP-ribose-accepting ability in spite of a significant residual enzyme activity. As used here successfully, the Mg2+-depleted and Mg2+-fortified ADP-ribosylation and subsequent chromatographic analysis of various proteins and enzymes might be an useful method for proving their oligo- and poly(ADP-ribosyl)ation.
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PMID:A method for determining oligo- and poly(ADP-ribosyl)ated enzymes and proteins in vitro. 400 56


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