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

The HaeIII methyltransferase (MTase) gene from Haemophilus aegyptius (recognition sequence: 5'-GGCC-3') was cloned into Escherichia coli in the plasmid vector pBR322. The gene was isolated on a single EcoRI fragment and on a single HindIII fragment. Clones carrying additional adjacent fragments were found to code also for the HaeII restriction endonuclease and HaeII modification MTase (recognition sequence: 5'-PuGCGCPy-3'). The sequence of the HaeIII modification gene was determined. The inferred amino acid sequence of the protein was found to share extensive similarity with other sequenced m5C-MTases. The central 'non-conserved' region of the M.HaeIII MTase, thought to form the nucleotide sequence-specificity domain, is almost identical to that of the M.BsuRI, M.BspRI and M.NgoPII MTases, which also recognize the sequence 5'-GGCC-3'.
...
PMID:Cloning and analysis of the HaeIII and HaeII methyltransferase genes. 324 32

We have dissected the cloned PstI M and R genes to make DNA hybridization probes spanning most of the sequence. These subclones, and also the intact sequence, were used to search for nucleic acid homology by Southern blot in the DNA from twelve organisms which produce PstI isoschizomers. One of these probes, a 206-bp fragment from the N-terminal domain of the endonuclease, showed significant hybridisation in four strains (Escherichia coli strains RFL48, RFL49 and RFL83, and Streptomyces albus P). No significant hybridisation was detected with other parts of the PstI sequences. We have used computer similarity searches to look for homology between the PstI proteins and the known sequences of other type-II systems that recognise different sites. We postulate a possible recognition domain within the M.PstI methyltransferase based on similarity to the M.PaeR7 and M.TaqI methyltransferases.
...
PMID:Investigation of sequence homology in a group of type-II restriction/modification isoschizomers. 326 58

A DNA methyltransferase was isolated from a eucaryotic, Chlorella-like green alga infected with the virus PBCV-1. The enzyme recognized the sequence GATC and methylated deoxyadenosine solely in GATC sequences. Host DNA, which contains GATC sequences, but not PBCV-1 DNA, which contains GmATC sequences, was a good substrate for the enzyme in vitro. The DNA methyltransferase activity was first detected about 1 h after viral infection; PBCV-1 DNA synthesis and host DNA degradation also began at about this time. The appearance of the DNA methyltransferase activity required de novo protein synthesis, and the enzyme was probably virus encoded. Methylation of DNAs with the PBCV-1-induced methyltransferase conferred resistance of the DNAs to a PBCV-1-induced restriction endonuclease enzyme described previously (Y. Xia, D. E. Burbank, L. Uher, D. Rabussay, and J. L. Van Etten, Mol. Cell. Biol. 6:1430-1439). We propose that the PBCV-1-induced methyltransferase protects viral DNA from the PBCV-1-induced restriction endonuclease and is part of a virus-induced restriction and modification system in PBCV-1-infected Chlorella cells.
...
PMID:DNA methyltransferase induced by PBCV-1 virus infection of a Chlorella-like green alga. 353 3

A 1476-base pair DNA fragment from Haemophilus haemolyticus containing the HhaI methyltransferase gene was isolated from a cell library and cloned into pBR322. The nucleotide sequence of this fragment was determined. The structural gene is 981 nucleotides in length coding for a protein of 327 amino acids (Mr 37,000). The translational start signal (ATG) is preceded by the putative ribosome-binding site (TAAG). Recombinant plasmids containing the 1476-basepair fragment are completely methylated when isolated from Escherichia coli, as judged by their insusceptibility to the HhaI restriction endonuclease. However, the presence of an active HhaI methylase gene in certain E. coli strains results in a very poor yield of transformants and/or in vivo-originated deletions due to the Rg1 functions of these hosts. The in vivo transcription initiation sites have been identified by S1 protection and primer-extension experiments using specific probes with total RNA prepared from E. coli cells (HB101 or RR1) which tolerate the expression of MHhaI.
...
PMID:Cloning, sequencing, in vivo promoter mapping, and expression in Escherichia coli of the gene for the HhaI methyltransferase. 354 10

We isolated a collection of chemotaxis mutants and characterized them for chemotactic phenotype and genotype. The mutations of most of these mutants mapped in the region between pyrD and thyA. However, the mutation in the gene specifying the chemotactic methyltransferase mapped very close to aroF. From a bank of phages containing Bacillus subtilis DNA we identified two lambda charon4 phages that contained genes specifying chemotactic functions. The inserted DNAs were removed by digestion with restriction endonuclease EcoRI and were found to share a 4.0-kilobase (kb) fragment. One of these DNAs also contained a 7.7-kb fragment, and the other also contained a 10.9-kb fragment. We identified mutants that were complemented by each fragment. The fragments were each ligated into plasmid pFH7 and were incorporated into lysogenic SP beta c2 or a deletion mutant of SP beta c2 in order to form transducing phages. The mutants in the collection containing mutations that mapped in the region between pyrD and thyA were tested for complementation by transducing phages containing the 4.0-kb fragment, the 7.7-kb fragment, the 4.0-kb fragment plus the 7.7-kb fragment, and the 10.9-kb fragment. A total of 24 mutants were complemented by the 4.0-kb fragment, 7 were complemented by the 7.7-kb fragment, 9 were complemented by the 4.0-kb fragment plus the 7.7-kb fragment, 15 were complemented by the 10.9-kb fragment, and 25 were complemented by none of the fragments.
...
PMID:Genetics of Bacillus subtilis chemotaxis: isolation and mapping of mutations and cloning of chemotaxis genes. 622 32

Organic synthesis and recombinant DNA technology were used to situate a putatively premutagenic DNA lesion, O6-methylguanine (O6MeGua), at a specific location in the genomes of two bacterial viruses, M13mp8 and phi X174, and of the bacterial plasmid pBR322. In each genome the first guanine residue in the unique recognition sequence for restriction endonuclease Pst I (5'-C-T-G-C-A-G-3') was replaced with O6MeGua. This was accomplished by ligating a chemically synthesized tetranucleotide, 5'-pTpm6GpCpA-3', into a circular, genome-length heteroduplex in which the four internal nucleotides of the Pst I recognition site had been removed from one strand of the DNA double helix (ligation yield, approximately equal to 50%). It was established that the tetranucleotide was located specifically at the Pst I site and that the presence of O6MeGua rendered the ligation product resistant to cleavage by Pst I. Sensitivity of the genome to Pst I was restored upon treatment with purified Escherichia coli O6MeGua DNA-methyltransferase, a repair protein that removes the methyl group from DNA-bound O6MeGua. This result, in combination with other data, showed unambiguously that O6MeGua was incorporated with high yield into the Pst I recognition sequence.
...
PMID:Construction and characterization of extrachromosomal probes for mutagenesis by carcinogens: site-specific incorporation of O6-methylguanine into viral and plasmid genomes. 632 Jan 61

An inducible methyltransferase of Escherichia coli acts on O6-methylguanine in DNA by conveying the methyl group to one of its own cysteine residues. The protein has now been purified to apparent homogeneity from a constitutively expressing strain. The homogeneous methyltransferase exhibits no DNA glycosylase or endonuclease activity on alkylated DNA. Further, the methyltransferase activity is strikingly resistant to heat inactivation under reducing conditions. The protein has Mr = 18,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while the sedimentation coefficient and Stokes radius of the native enzyme yield Mr = 18,400. The amino acid composition of the purified protein shows 4 to 5 cysteine residues/transferase molecule. The methylated, inactive form of the transferase has an unaltered molecular weight.
...
PMID:Repair of alkylated DNA in Escherichia coli. Physical properties of O6-methylguanine-DNA methyltransferase. 675 17

The ability of extracts of human tumor cells to demethylate O6-methylguanine (O6-MeG) in DNA was assayed using the synthetic DNA polymer poly(dC,dG,m6dG). Cell strains proficient in repair of O6-MeG in vivo (Mer+ phenotype) contained a methyltransferase activity while repair deficient cells (Mer- phenotype) had little or no activity. Mixing extracts of different Mer- strains did not result in the appearance of the activity. Extracts of Mer- cells did not inhibit the activity in extracts of Mer+ cells. Both Mer+ and Mer- strains contained methylnitrosourea-damage-specific endonuclease activity. The data suggest that the Mer- strains are deficient in methyltransferase and that this is the fundamental reason for their hypersensitivity to the cytotoxic effects of DNA alkylation. The activity was partially purified from a Mer+ colon carcinoma cell strain. Its kinetics parallel the repair of O6-MeG in DNA in vivo and suggest that the activity is inactivated during repair of DNA.
...
PMID:Repair of O6-methylguanine in DNA by demethylation is lacking in Mer- human tumor cell strains. 682 8

We report the organization of the HpaII restriction and modification (R-M) system from Haemophilus parainfluenzae (recognition sequence: 5'...CCGG...3'), the sequence of the gene coding for the HpaII restriction endonuclease, and the sequence of the upstream flanking DNA. The HpaII system comprises two genes, hpaIIM, coding for the methyltransferase (MTase; 358 amino acids (aa), 40.4 kDa: product, Cm5CGG), and hpaIIR, coding for the restriction endonuclease (ENase; 358 aa, 40.9 kDa: product, C'CGG). The genes are adjacent, they have the same orientation, and they occur in the order hpaIIM then hpaIIR. The ENase bears little as sequence similarity to the isoschizomeric R.BsuFI and R.MspI ENases. Upstream of, and partly overlapping hpaIIM is the coding sequence for a 141-aa protein that resembles the very-short-patch-repair endonuclease (Vsr) of Escherichia coli. Upstream of that is the coding sequence for a protein that resembles valyl-tRNA synthetase (ValS).
...
PMID:Organization and sequence of the HpaII restriction-modification system and adjacent genes. 751 49

The gene (cviJIR) encoding the two/three-base R.CviJI eukaryotic restriction endonuclease (ENase) from IL-3A virus-infected Chlorella was cloned into Escherichia coli. A high frequency of DNA cleavage by R.CviJI required overexpression of the gene encoding the M.CviJI methyltransferase prior to cloning the gene for the ENase. Both genes were sequenced and their organization was determined to be in head-to-tail order. The open reading frame coding for R.CviJI can potentially translate a 41.4-kDa protein; however, in the E. coli host, a truncated version of the enzyme is produced (32.5 kDa). The recombinant ENase does not exhibit ATP-induced 'star' activity (R.CviJI cleaves at RGCY, while R.CviJI* also cleaves at RGCR and YGCY, but not at YGCR), as is characteristic for native R.CviJI. The very high frequency of DNA cleavage by R.CviJI* was exploited in the development of a quasi-random shotgun library method. R.CviJI*-generated oligodeoxyribonucleotides were applied to improve certain molecular biology applications, i.e., DNA labeling, detection, high-resolution restriction mapping, amplification and epitope mapping.
...
PMID:Cloning and applications of the two/three-base restriction endonuclease R.CviJI from IL-3A virus-infected Chlorella. 760 22


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---