Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purified A protein and A* protein of bacteriophage phi X174 have been tested for endonuclease activity on single stranded viral phi X174 DNA. The A protein (55.000 daltons) nicks single-stranded DNA in the same way and at the same place as it does superhelical RFI DNA, at the origin of DNA replication. The A* protein (37.000 daltons) can cleave the single-stranded viral DNA at many different sites. It has however a strong preference for the origin of replication. Both proteins generate 3'OH ends and blocked 5' termini at the nick site.
Nucleic Acids Res 1979 Dec 20
PMID:Cleavage of single-stranded DNA by the A and A* proteins of bacteriophage phi X174. 16 May 44

The block to adenovirus 2 (Ad2) multiplication in monkey cells can be overcome by coinfection with simian virus 40 (SV40). To identify this block we have compared the synthesis of Ad2 proteins in monkey cells infected with Ad2 alone (unenhanced) or with Ad2 plus SV40 (enhanced). Synthesis of viral proteins in enhanced cells was virtually identical to that found for permissive infection of human cells by Ad2 alone. In contrast, the unenhanced cells were strikingly deficient in the production of the IV (fiber) and 11.5K proteins whereas the synthesis of 100K and IVa2 was normal. Synthesis of a number of other proteins such as II, V, and P-VII was partially reduced. A similar specific reduction in synthesis of these proteins was found when their messages were assayed by cell-free translation. This result suggests that the block to Ad2 protein synthesis is at the RNA level rather than with the translational machinery of monkey cells. Analysis of the complexity and the concentration of Ak2-specific RNAs, using hybridization of restriction endonuclease fragments of the Ad2 genome to increasing concentrations of RNA, shows that although all species of late Ad2 mRNA are present, the concentration of several species is reduced sevenfold or more in unenhanced monkey cells as compared with enhanced cells. These species come from regions of the genome known to encode the deficient proteins. A model for the failure of adenovirus to multiply in monkey cells, based on abnormal processing of specific adenovirus messages, is presented.
J Virol 1975 Dec
PMID:Block to multiplication of adenovirus serotype 2 in monkey cells. 17 61

An endonuclease activity has been purified approximately 800-fold from nuclei of 3T3 cells infected with polyoma virus. The purfied enzyme catalyzes an endonucleoytic cleavage of single- and double-stranded DNA and single-stranded RNA. Evidence that the activity towards these substrates resides in the same protein molecule is provided by the finding that they co-sediment in sucrose gradients and have identical rates of heat inactivation. Studies on the DNase activity shows that the rate of hydrolysis of single-stranded T7 DNA is 100-fold greater than that for double-stranded T7 DNA. Single-stranded DNA is extensively hydrolyzed to low molecular weight acid-insoluble products. With duplex DNA as substrate, only a limited number of single strand breaks are introduced. A limit digest with polyoma DNA (component I) as substrate results in the introduction of four breaks per strand. The phosphdiester bond interruptions can be repaired by polynucleotide ligase. Approximately 80% of the 5' termini present at the point of phosphodiester bond cleavage are purine nucleotides. Additional studies have demonstrated that a similar endonuclease is present in nuclei of uninfected cells and that this enzyme purified 400-fold has catalytic properties identical with those of the endonuclease from infected cells.
J Biol Chem 1976 Dec 25
PMID:Purification and properties of an endonuclease from nuclei of uninfected and polyoma-infected 3T3 cells. 18 96

Complex simian virus 40 DNA produced by a soluble cell-free extract derived from stage 6 oocytes of Xenopus laevis consists of fully relaxed circles (i.e., with no superhelical turns). An endonuclease and a DNA-relaxing protein, either or both of which could be responsible for the relaxation of the complex DNA, have been purified from the extract. The endonuclease(s) produces nicked circles (having a single-strand scission) and linear full-size molecules. The DNA-relaxing protein is in the nucleus, has a molecular weight of apporximately 70,000, and is able to remove both negative and positive superhelical turns.
Proc Natl Acad Sci U S A 1976 Dec
PMID:DNA-relaxing activity and endonuclease activity in Xenopus laevis oocytes. 18 45

Primary cultures of human umbilical vein endothelial cells (HEC) developed extensive cytopathic changes and necrosis after high multiplicity infection with wild-type SV40 virus. Using the calcium co-precipitation technique, stable transformation was obtained with purified preparations of intact circular SV40 DNA and restriction endonuclease-derived linear DNA fragments containing the entire early gene region. Smooth muscle cells, isolated from the same blood vessels, showed neither cytopathic effects nor transformation after similar treatment with SV40 virus or DNA. The HEC cultures transformed by SV40 (SVHEC) expressed SV40-specific T (tumor) and Tr (transplantation) antigens, but not V (viral capsid) antigen. No evidence of infectious virus production was found upon co-cultivation with the CV-1 line of monkey kidney cells. Transformation resulted in markedly increased growth potential, loss of anchorage dependence and topoinhibition of growth, and a reduced serum requirement. Prolonged subcultivation was accompanied by chromosomal abnormalities and eventual "crisis". Transformed cells did not exhibit endothelial-specific organelles (Weibel-Palade bodies) or factor VIII antigen, but angiotensin-converting enzyme occasionally was detectable in SVHEC cultures. SV40-transformed human vascular endothelium, a nonfibroblast diploid cell type, may be useful in studies of oncogenesis and control of the differentiated state.
Cell 1976 Dec
PMID:Transformation of cultured human vascular endothelium by SV40 DNA. 18 41

This paper describes the successful construction and propagation of a transducing animal virus. A segment of DNA approximately 2 kilobases (kb) in length was removed from the late region of the SV40 genome by sequential cleavages with Hpa II and Bam HI endonucleases (at 0.735 and 0.13, respectively, on the SV40 DNA map). A segment of about 1.5 kb of lambda phage containing ORI (the origin of lambda DNA replication), the two structural genes CII and cro, and four transcriptional promoters, was inserted into the late region of SV40 by the poly(dA:dT) joining procedure. The resulting hybrid DNAs were cloned and propagated as virions in CV-1 monkey kidney cells by mixed infections at 41 degrees C with tsA58, an early mutant of SV40. The location, size, and orientation of the inserted lambda DNA segment was verified by restriction endonuclease digestions and by heteroduplex analysis. Clones with each of the two possible orientations of the lambda DNA segment were isolated. CV-1 cells infected with lambda-SV40 hybrid virus contain little or no lambda-specific RNA or proteins, even though the hybrid virus replicates nearly as well as the helper virus.
Cell 1976 Dec
PMID:Construction of hybrid viruses containing SV40 and lambda phage DNA segments and their propagation in cultured monkey cells. 18 42

A homogeneous preparation of venom phosphodiesterase from Crotalus adamanteus possesses an intrinsic endonuclease activity, specific for superhelical (form I) and single-stranded DNA. The phosphodiesterase degrades single-stranded T7 DNA by endonucleolytic cleavages. Duplex T7 DNA is hydrolyzed by the liberation of acid-soluble products simultaneously from the 3' and 5' termini but without demonstrable internal scissions in duplex regions. Since venom phosphodiesterase is known to hydrolyze oligonucleotides stepwise from the 3' termini, the cleavage at the 5' end of duplex T7 DNA is ascribed to an endonuclease activity. Form I PM2 DNA is nicked to yield first relaxed circles and then linear DNA which is subsequently hydrolyzed only from the chain termini. The linear duplex DNA intermediates consist of a discrete series of fragments (11 are usually resolved on agarose gels) with initial molecular weights ranging from 6.3 x 10(6) (the intact PM2 DNA size) to approximately 1 x 10(6). The cleavage of the form I molecule must, therefore, occur at a limited number of unique sites. The enzyme also cleaves nonsuperhelical, covalently closed circular PM2 DNA but at a 10(4) times slower rate. Both the endonuclease activity on form I DNA and the known exonuclease activity co-migrate on polyacrtkanude gels, are optimally active at pH 9, are stimulated by small concentrations of Mg2+, and are similarly inactivated by heat, reducing agents, and EDTA.
J Biol Chem 1977 Dec 10
PMID:An endonuclease activity of venom phosphodiesterase specific for single-stranded and superhelical DNA. 20 Jun 16

Circular viral DNA intermediates obtained from the quail tumor line, QT6, at 1 day after infection, were opened at one specific location by the single-strand specific nuclease, S1, of Aspergillus oryzae. This site was no longer accessible to the S1 nuclease when circles were first opened at another location with a restriction endonuclease.
J Virol 1978 Dec
PMID:Specific site of action for single-strand specific nuclease on the double-stranded circular DNA intermediates of an avian RNA tumor virus. 21 77

A new restriction endonuclease, SacI from Streptomyces achromogenes cleaves BK virus (strain MM) DNA into 3 fragments, whereas MboII from Moraxella bovis and AluI from Arthrobacter luteus give 22 and 30 fragments, respectively. All these specific DNA fragments were ordered and mapped on the viral genome by two methods first, by the reciprocal digestion method using uniformly 32P-labeled DNA; and second, by the partial digestion technique using the single-end 32P-labeled DNA. This study, together with those reported earlier, defined the location of 90 cleavage sites on the BK virus DNA.
J Virol 1978 Dec
PMID:Physical mapping of BK virus DNA with SacI, MboII, and AluI restriction endonucleases. 21 83

Isolated simian virus 40 (SV40) and polyoma nucleoprotein complexes contain endonuclease that, under in vitro conditions, converts part (up to 30%) of the covalently closed superhelical DNA to full-length linear rods. The positions of the cleavage sites within the genomes of SV40 and polyoma were determined by digestion with various single-cut restriction endonucleases and subsequent agarose gel electrophoresis of the cleavage products. Both SV40 and polyoma covalently closed superhelical DNA were cleaved open at their respective origins of DNA replication (+/- 75 base pairs). The full-length linear DNA rods whose ends map adjacent to the origin of DNA replication could also be isolated by sodium dodecyl sulfate/phenol extraction both from SV40-infected permissive cells and from purified SV40 virions. These data reveal the presence of a unique structure of the papovavirus chromatin close to the initiation site of DNA replication.
Proc Natl Acad Sci U S A 1978 Dec
PMID:Origin of DNA replication in papovavirus chromatin is recognized by endogenous endonuclease. 21 4


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