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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The inducible quinic acid catabolic pathway of Neurospora crassa is controlled by four genes, the qa cluster which includes structural genes qa-2, qa-3, qa-4 for three enzymes and a regulatory gene, qa-1. In this paper we report the molecular cloning of at least the qa-2 gene which encodes the catabolic dehydroquinase (5-dehydroquinate hydro-lyase, EC 4.2.1.10). Endo.R.HindIII restriction endonuclease fragments of N. crassa DNA from a qa-1(c) (constitutive) mutant and of Escherichia coli plasmid pBR322 DNA were ligated in vitro and used to transform an aroD6 (5-dehydroquinate hydrolyase deficient) strain of E. coli K12. The recombinant plasmid (pVK55) isolated from one AroD(+) transformant (SK1518) contained, in addition to pBR322, two N. crassa HindIII fragments with molecular weights of 2.3 x 10(6) and 1.9 x 10(6). Derivatives of SK1518 cured of plasmid DNA were phenotypically Amp(s) and AroD(-). These cured strains, retransformed with pVK55, were phenotypically Amp(R) and AroD(+). Strains transformed with pVK55 possessed 5-dehydroquinate hydrolyase activity but no activity was present in any AroD(-) strain. The enzyme extracted from strains containing the recombinant plasmid was identical to N. crassa catabolic dehydroquinase by the criteria of heat stability, ammonium sulfate fractionation, immunological crossreactivity, molecular weight, and purification characteristics. This identity demonstrates that the N. crassa qa-2(+) gene is carried by the recombinant plasmid and is apparently transcribed and translated with complete fidelity. Furthermore, subunit assembly of the N. crassa polypeptides also occurs in E. coli, because the catabolic dehydroquinase is a multimer composed of approximately 20 identical subunits.
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PMID:Expression in Escherichia coli K-12 of the structural gene for catabolic dehydroquinase of Neurospora crassa. 14 63

The effects of Eco RI endonuclease-cleaved Escherichia coli and yeast (Saccharomyces cerevisiae) DNA fragments on the propagation of the lambda bacteriophage vectors containing them were determined on a nonmutanted and a PolA E. coli K12 host. Observable alterations in the growth of hybrids containing yeast DNA insertions were less frequent and less extreme than those seen in hybrids containing E. coli DNA. A lambda-E. coli hybrid was selected after extensive growth on the Pol A (deficient in polymerase I) host which also grew very well on the PolA+ host and may have resulted from some alteration in the hybrid. Hybrids selected on the PolA host gave no evidence for the expression of polymerase I activity. No lambda-yeast hybrid made from the lambdagt vector lacking lambda-specific recombination (red-) had a yield of viable bacteriophage on infection greater than two-thirds that of "wild-type" lambda.
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PMID:The effects of Escherichia coli and yeast DNA insertions on the growth of lambda bacteriophage. 32 85

The DNA of an E. coli K12 strain harboring ten wildtype Mu prophages was restricted with endonuclease EcoRI, and the fragments ligated into the plasmid vector pMB9. Upon transformation of a strain carrying a heat inducible (Mu cts62) prophage, one temperature-resistant transformant was isolated. This transformant strain harbors the hybrid plasmid pKN001, containing the EcoRI.C fragment of Mu DNA as shown by restriction and heteroduplex analysis. Stable transformants of pKN001 are immune to superinfection with phage Mu. Transformation of Mu sensitive bacteria with pKN001 results in killing of the recipients (10(-4) surviving bacteria). The killing function is not expressed upon transformation of Mu-immune (lysogenic) bacteria.
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PMID:Cloning of a restriction fragment of phage mu DNA coding for early functions. 34 45

The recognition sequence for the dam methylase of Escherichia coli K12 has been determined directly by use of in vivo methylated ColE1 DNA or DNA methylated in vitro with purified enzyme. The methylase recognizes the symmetric tetranucleotide d(pG-A-T-C) and introduces two methyl groups per site in duplex DNA with the product of methylation being 6-methylaminopurine. This work has also demonstrated that Dpn I restriction endonuclease cleaves on the 3' side of the modified adenine within the methylated sequence to yield DNA fragments possessing fully base-paired termini. All sequences in ColE1 DNA methylated by the dam enzyme are subject to double strand cleavage by Dpn I endonuclease. Therefore, this restriction enzyme can be employed for mapping the location of sequences possessing the dam modification.
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PMID:Recognition sequence of the dam methylase of Escherichia coli K12 and mode of cleavage of Dpn I endonuclease. 36 70

The methods of isolation and partial purification of two DNA-cytosine-methylases (DC-methylases) EcoRII and E. coli K12 are described. After chromatography on phosphocellulose the enzymes were purified 100-fold, the yield being 30%. Further purification of the enzymes was performed by sedimentation in a sucrose concentration gradient. Both enzymes have native molecular weights of 50,000; DC-methylase from E. coli K12 may simultaneously occur in the forms with molecular weights of 70,000, 90,000 and 110,000. Both DC-methylases modify identical nucleotide sequences of DNA, have equal numbers (90) of methylation sites in phage lambda DNA and provide in vitro a complete protection of phage lambda DNA against restriction endonuclease EcoRII. DC-methylases E. Coli K12 and EcoRII differ in their chromatographic behaviour on phosphocellulose and capacity to form compexes with the cell DNA-adenine-methylase.
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PMID:[Isolation and properties of DNA-cytosine-methyltransferase EcoRII and E. coli K12]. 38 Jun 60

Hybrid plasmids were constructed from fragments of F'ara episomes formed by the restriction endonuclease EcoRI and a linear form of the plasmid ColE1 created by cleavage with EcoRI. Hybrid plasmids were constructed containing the entire ara region or the ara region with various parts deleted. E. coli K12 host strains were constructed which contained different deletions of the ara region. The hybrid plasmids were transferred to those strains whose ara deletion complemented that of the plasmid. The initial differential rates of synthesis of L-arabinose isomerase, the product of the araA gene, were determined for the Ara+, plasmid containing strains. These studies demonstrated that strains containing delta(araOIBA)718 produce elevated levels of araC protein, suggesting the araC promoter has been altered by this deletion. Evidence is also presented which suggests that araC protein activates the ara-BAD operon to higher levels when it is present in cis rather than trans. Amplification of the products of the cloned genes is observed when compared to haploid levels in some cases.
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PMID:Regulation of the L-arabinose operon in strains of Escherichia coli containing ColE1-ara hybrid plasmids. 38 53

DNA fragments of phage PM2 restricted with Hin dIII endonuclease was cloned in the vector pBR 322 in an Escherichia coli K12 host. The attempt to clone full length PM2 DNA restricted with PstI endonuclease has been unsuccesful. From six randomly chosen recombinant clones DNA was purified and analysed with EcoRI, PstI and Hin dIII endonucleases. The physical map of three chimeric plasmids was unequivocally established. It was shown, that the whole PM2 genome was cloned, although in separate fragments. However, most of the recombinant clones were instable in the absence of selective pressure.
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PMID:Cloning of bacteriophage PM2 DNA in Escherichia coli K12. 39 43

Bacteriophage T3 and T7 protect their DNA from restriction by producing, as the earliest detectable phage functions, anti-restriction proteins. Although the two phage proteins differ in their chromatographic and antigenic properties, they act by the same mechanism: the anti-restriction proteins inhibit E. coli K12 restriction endonuclease by direct interaction.
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PMID:A novel bacteriophage defence mechanism: the anti-restriction protein. 76 48

Using the single-stranded circular DNA of bacteriophage fd as template, double-stranded circular DNA has been prepared in vitro with either 5-hydroxymethylcytosine ([hmdC]DNA) or cytosine ([dC]DNA) in the product strand. Extracts prepared from Escherichia coli cells restrictive to T-even phage containing nonglucosylated DNA degrade [hmdC]DNA to acid-soluble material in vitro, but do not degrade [dC]dna. In contrast, extracts prepared from E. coli K12 rglA- rglB-, a strain permissive to T-even phage containing nonglucosylated DNA, do not degrade [hmdC]DNA or [dC]DNA. In addition, glucosylation of the [hmdC]DNA renders it resistant to degradation by extracts from restrictive strains. The conversion of [hmdC]DNA to acid-soluble material in vitro consists of an HmCyt-specific endonucleolytic cleavage requiring the presence of the RglB gene product to form a linear molecule, followed by a non-HmCyt-specific hydrolysis of the linear DNA to acid-soluble fragments, catalyzed in part by exonuclease V. The RglB protein present in extracts of E. coli K12 rglA- rglB+ has been purified 200-fold by complementation with extracts from E. coli K12 rglA- rglB-. The purified RglB protein does not contain detectable HmCyt-specific endonuclease or exonuclease activity. In vitro endonucleolytic cleavage of [hmdC]DNA thus requires additional factors present in cell extracts.
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PMID:Modification and restriction of T-even bacteriophages. In vitro degradation of deoxyribonucleic acid containing 5-hydroxymethylctosine. 76 37

Recombinant DNAs containing the E. coli plasmid pSC101 and mouse cell (La9) mitochondrial DNA (mtDNA) were formed in vitro via ligation of DNA fragments from limit EcoRI endonuclease digests and were used to transform E. coli K12. Four structurally different recombinant plasmid DNAs from transformed clones were characterized. Two of these were analyzed extensively and the mtDNA portions compared with mtDNA from LA9 cells. No differences were detected in the physical or chemical properties examined, except that the E. coli mtDNA lacked the alkali lability characteristic of animal mtDNAs. Heteroduplexes between the LA9 portions of the recombinant plasmids and LA9 mtDNA were analyzed by absorbance melting. The melting temperatures were indistinguishable from reannealed LA9 mtDNA homoduplexes, indicating that single-base replication errors occur at a frequency of fewer than 1 nucleotide in 300. Electron microscopic analyses of plasmid-LA9 mtDNA heteroduplexes and a comparison of agarose gel electrophoresis of restriction endonuclease fragments also indicated no differences. These results were independent of the order or the relative orientation of the pSC101 and mtDNA fragments. A third EcoRI fragment in LA9 mtDNA, not found in an earlier study (Brown and Vinograd, 1974), has been positioned in the LA9, EcoRI map. This fragment contains 165+/-10 nucleotide pairs.
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PMID:The structures and fidelity of replication of mouse mitochondrial DNA-pSC 101 EcoRI recombinant plasmids grown in E. coli K12. 78 20


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