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)

A specific endonuclease, Sau 3AI, has been partially purified from Staphylococcus aureus strain 3A by DEAE-cellulose chromatography. The enzyme cleaves adenovirus type 5 DNA many times, SV40 DNA eight times but does not cleave double-stranded phi X174 DNA. It recognizes the sequence (see article) and cleaves as indicated by the arrows. Evidence is presented that this enzyme plays a role in the biological restriction-modification system of Staphylococcus aureus strain 3A.
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PMID:A restriction endonuclease from Staphylococcus aureus. 100 15

The Mg-2+-Sarkosyl crystals (M band) procedure was used to study the effect of ribonuclease (RNase) A on the association of Escherichia coli deoxyribonucleic acid (DNA) with membrane. Incubation of gently prepared cell extracts with RNase results in the release of DNA from membrane. This effect appears to result from the activation, by RNase, of endonuclease I and subsequent limited activity of this deoxyribonuclease. In support of this explanation, it is demonstrated (i) that the extent of the RNase-induced loss of DNA from membrane is directly correlated with the endogenous level of endonuclease I, and (ii) that endonucleolytic activity occurs when gently lysed cell preparations are incubated in the presence of RNase.
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PMID:Effect of ribonuclease on the association of deoxyribonucleic acid with the membrane in Escherichia coli. 109 60

The recently isolated neutral deoxyribonuclease from crab (Cancer pagurus) testes has been characterized in its mode of action and its specificity. The enzyme is a typical endonuclease, forming 5'-phosphate oligonucleotides of large average size; after extensive digestion of calf thymus DNA over 75% of the fragments have a size larger than pentanucleotides and mononucleotides are absent. As far as specificity is concerned, thymidine is very abundant in the 5'-penultimate position (approximately 50%) and in the 3'-terminal position (37%) and almost absent in the 5'-terminal position (approximately 1%), the values quoted concerning Escherichia coli digests of average size (Pn) between 50 and 10.
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PMID:The specificity of a neutral deoxyribonuclease from Cancer pagurus. 123 41

A 6.3 kb fragment of E.coli RFL57 DNA coding for the type IV restriction-modification system Eco57I was cloned and expressed in E.coli RR1. A 5775 bp region of the cloned fragment was sequenced which contains three open reading frames (ORF). The methylase gene is 1623 bp long, corresponding to a protein of 543 amino acids (62 kDa); the endonuclease gene is 2991 bp in length (997 amino acids, 117 kDa). The two genes are transcribed convergently from different strands with their 3'-ends separated by 69 bp. The third short open reading frame (186 bp, 62 amino acids) has been identified, that precedes and overlaps by 7 nucleotides the ORF encoding the methylase. Comparison of the deduced Eco57I endonuclease and methylase amino acid sequences revealed three regions of significant similarity. Two of them resemble the conserved sequence motifs characteristic of the DNA[adenine-N6] methylases. The third one shares similarity with corresponding regions of the PaeR7I, TaqI, CviBIII, PstI, BamHI and HincII methylases. Homologs of this sequence are also found within the sequences of the PaeR7I, PstI and BamHI restriction endonucleases. This is the first example of a family of cognate restriction endonucleases and methylases sharing homologous regions. Analysis of the structural relationship suggests that the type IV enzymes represent an intermediate in the evolutionary pathway between the type III and type II enzymes.
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PMID:Cloning and sequence analysis of the genes coding for Eco57I type IV restriction-modification enzymes. 133 61

Over 60 producing strains of restriction endonucleases type II have been found among 500 different strains, mostly Enterobacteriaceae. The strain Citrobacter freundii 4111 produces restriction endonuclease CfrBI, a new isoschisomer of StyI. The genes of the restriction-modification system CfrBI were located on the multicopy plasmid pZE8 containing the Co1E1-type replicon and cloned to E. coli K802. The deletion variant of 3.2-kb pZE8 which contains intact restriction-modification and a DNA fragment responsible for autonomous plasmid replication was selected among the recombinant plasmids. The strain with higher R. CfrBI production (at least 10,000,000 U/g cells, which is 500-fold higher than the wild strain) was constructed.
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PMID:[Plasmid localization and cloning of restriction modification genes from Citrobacter freundii 4111 strain]. 133 50

The genes of the AccI restriction-modification system specific for GT(A/C) (G/T)AC were cloned from the chromosomal DNA of Acinetobacter calcoaceticus, and their nucleotides sequenced. The restriction and modification genes coded for polypeptides with calculated molecular weights of 42,494 and 63,078, respectively. Both the enzymes were coded by the same DNA strand and the restriction gene was upstream of the methylase gene, separated by 2 bp. The restriction gene was significantly expressed in E. coli cells, so that the AccI restriction endonuclease could be purified to homogeneity. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration indicated that the catalytically active form of the endonuclease was tetrameric. Sequence comparison with related enzymes indicated that AccI methylase contained a segment of tetra-amino acids, NPPY, characteristic of N6-adenine methylases. In addition, some homologous regions were found in the sequence of HincII methylase specific for GT(C/T) (A/G)AC.
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PMID:Cloning and nucleotide sequences of the AccI restriction-modification genes in Acinetobacter calcoaceticus. 136 3

The restriction-modification system, named RMMunI, has been purified and characterised from Friend murine erythroleukemia cells. The site-specific endonuclease recognizes and cleaves the 5'C1AATTG nucleotide sequence. RMunI is an isoschizomer of RMfeI from Mycoplasma fermentans. Site-specific methylase modifies the second adenine residue in the same sequence (5'Cam6ATTG). It was established that the discovered enzymatic system is from mycoplasma which contaminates cell lines. Mycoplasma's DNA hybridizes with species-specific DNA probed for Mycoplasma fermentans and Mycoplasma arginini. The possible role of mycoplasmic restriction-modification enzymes in the process of acquired immune deficiency syndrome are discussed.
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PMID:[Mycoplasma restriction-modification system MunI and its possible role in pathogenesis processes]. 140 10

BamHI, from Bacillus amyloliquefaciens H, is a type II restriction-modification system recognizing and cleaving the sequence G--GATCC. The BamHI restriction-modification system contains divergently transcribed endonuclease and methylase genes along with a small open reading frame oriented in the direction of the endonuclease gene. The small open reading frame has been designated bamHIC (for BamHI controlling element). It acts as both a positive activator of endonuclease expression and a negative repressor of methylase expression of BamHI clones in Escherichia coli. Methylase activity increased 15-fold and endonuclease activity decreased 100-fold when bamHIC was inactivated. The normal levels of activity for both methylase and endonuclease were restored by supplying bamHIC in trans. The BamHI restriction-modification system was transferred into Bacillus subtilis, where bamHIC also regulated endonuclease expression when present on multicopy plasmid vectors or integrated into the chromosome. In B. subtilis, disruption of bamHIC caused at least a 1,000-fold decrease in endonuclease activity; activity was partially restored by supplying bamHIC in trans.
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PMID:Regulation of the BamHI restriction-modification system by a small intergenic open reading frame, bamHIC, in both Escherichia coli and Bacillus subtilis. 142 43

The XcyI restriction-modification system from Xanthomonas cyanopsidis recognizes the sequence, CCCGGG. The XcyI endonuclease and methylase genes have been cloned and sequenced and were found to be aligned in a head to tail orientation with the methylase preceding and overlapping the endonuclease by one base pair. The nucleotide sequence codes for an N4 cytosine methyltransferase with a predicted molecular weight of 33,500 and an endonuclease comprised of 333 codons and a molecular weight of 36,600. Sequence comparisons revealed significant similarity between the XcyI, CfrI and SmaI methylisomers. In contrast, no similarity was detected between the primary structures of the XcyI and SmaI endonucleases. The XcyI restriction-modification system is highly homologous to the XmaI genes, although the DNA sequences flanking the genes rapidly diverge. The sequence of the XcyI endonuclease contains two motifs which have recently been identified as essential to the activity of the EcoRV endonuclease.
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PMID:Structure and evolution of the XcyI restriction-modification system. 147 87

A restriction-modification system, designated MthTI, was localized on plasmid pFV1 from the thermophilic archaeon Methanobacterium thermoformicicum THF. The MthTI system is a new member of the family of GGCC-recognizing restriction-modification systems. Functional expression of the archaeal MthTI genes was obtained in Escherichia coli. The mthTIR and mthTIM genes are 843 and 990 bp in size and code for proteins of 281 (32,102 Da) and 330 (37,360 Da) amino acids, respectively. The deduced amino acid sequence of M.MthTI showed high similarity with that of the isospecific methyltransferases M.NgoPII and M.HaeIII. In addition, extensive sequence similarity on the amino acid level was observed for the endonucleases R.MthTI and R.NgoPII. Moreover, the endonuclease and methyltransferase genes of the thermophilic MthTI system and those of the Neisseria gonorrhoeae NgoPII system show identical organizations and high (54.5%) nucleotide identity. This finding suggests horizontal transfer of restriction-modification systems between members of the domains Bacteria and Archaea.
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PMID:Characterization of the archaeal, plasmid-encoded type II restriction-modification system MthTI from Methanobacterium thermoformicicum THF: homology to the bacterial NgoPII system from Neisseria gonorrhoeae. 151 4


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