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)

We have identified cloned fragments of the soybean genome that hybridize to total soybean tRNA. Five of these clones, chosen at random, have unique patterns of restriction endonuclease sites and contain only a small region that is homologous to tRNA (less than 1 kb of 10-12 kb cloned). Two of the hybridizing fragments were subcloned and regions of about 600 bp including the homologies were sequenced. Each region contains a single putative tRNA gene, for tRNAasp or tRNAmet, surrounded by DNA rich in AT basepairs (68-82%). Neither sequence encodes the amino acid-accepting -CCA terminus. The tRNAasp gene does not contain any intervening sequences, but the tRNAmet gene has an 11-bp sequence in the anticodon loop that would not be expected in the mature tRNA. There appear to be a small number of sequences within the soybean genome that share homology with each of the regions containing a putative tRNA gene.
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PMID:Plant tRNA genes: putative soybean genes for tRNAasp and tRNAmet. 404 Jan 49

A mutant that rapidly degrades more than 80% of its rRNA and tRNA under defined conditions was genetically analyzed. Two genes, srnA and srnB, are separately located, and the mutated alleles of both are required for degradation of stable RNA in cultures treated with rifampicin at 42 degrees . srnA is closely linked to tsx by matings and transduction tests; by P1 transduction, the gene order is lac (9 min) proC (9.55 min) tsx (9.8 min) srnA (about 10 min) purE (12 min) rnsA (14.4 min). srnB is not yet completely mapped, but is outside the lac-rnsA region, probably in the region between 75 and 90 min.-The product of the rnsA gene, RNase I, is a potent endonuclease of E. coli, and the only one known that can attack ribosomes and tRNA. However, not only are the srn lesions genetically separate from rnsA, but also, derivatives of an srn strain were prepared lacking RNase I, and they retain the Srn(-) phenotype. Thus, no correlation of rapid RNA turnover and RNase I activity has been found.
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PMID:Genetic analysis of an Escherichia coli mutant with a lesion in stable RNA turnover. 459 41

A gene specifying tyrosine transfer RNA has been purified and transcribed in vitro. The purification procedure made use of two specialized transducing phages carrying the tRNA(Tyr) gene of Escherichia coli inserted into their DNA in opposite orientations. The separated heavy strands of the two phages were annealed and the single-stranded tails of the resulting hybrid were removed by digestion with Neurospora endonuclease. The size of the purified double-stranded structures was determined by electron microscopy. These isolated duplexes served as template for the in vitro transcription of tRNA(Tyr)-like molecules.
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PMID:Purification and in vitro transcription of a transfer RNA gene. 494 95

Splicing of transfer RNA precursors containing intervening sequences proceeds in two distinct stages: endonucleolytic cleavage, followed by ligation. We have physically separated endonuclease and ligase activities from extracts of yeast cells, and we report properties of the partially purified endonuclease preparation. The endonuclease behaves as an integral membrane protein: it is purified from a membrane fraction from which it can be solubilized with nonionic detergents, and the activity of the endonuclease in the membrane fraction is stimulated by nonionic detergents. The endonuclease cleaves precursor tRNAs at two sites to excise the intervening sequence precisely. Both the extent and the accuracy of cleavage are enhanced by the presence of spermidine; the degree of stimulation varies with the pre-tRNA substrate. The cleavage products possess 5'-hydroxyl and 2',3'-cyclic phosphodiester termini. The cyclic phosphodiester termini can be opened to 2'-phosphates by a cyclic phosphodiesterase activity in the preparation.
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PMID:Precise excision of intervening sequences from precursor tRNAs by a membrane-associated yeast endonuclease. 618 98

The interactions between beef tRNATrp with avian myeloblastosis reverse transcriptase have been studied by statistical chemical modifications of phosphate (ethylnitrosourea) and cytidine (dimethyl sulfate) residues, as well as by digestion of complexed tRNA by Cobra venom nuclease and Neurospora crassa endonuclease. Results with nucleases and chemicals show that reverse transcriptase interacts preferentially with the D arm, the anticodon stem and the T psi stem. All these regions are located in the outside of the L-shaped structure of tRNA. This domain of interaction is different to that reported previously in the complex of beef tRNA with the cognate aminoacyl-tRNA synthetase (M. Garret et al.; Eur. J. Biochem. In press). Avian reverse transcriptase destabilizes the region of tRNA where most of the tertiary interactions maintaining the structure of tRNA are located.
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PMID:Interactions between avian myeloblastosis reverse transcriptase and tRNATrp. Mapping of complexed tRNA with chemicals and nucleases. 620 Aug 30

DNA segments carrying rRNA genes of Mycoplasma capricolum have been cloned and characterized by restriction endonuclease mapping, DNA-RNA hybridization and nucleotide sequencing. The M. capricolum genome has two sets of rRNA gene clusters, where the arrangement is in the order of (5')16S-23S-5S(3'). The spacer region between 16S and 23S rDNA is extremely rich in AT and does not carry any tRNA genes.
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PMID:Organization of ribosomal RNA genes in Mycoplasma capricolum. 620 57

An endonuclease activity was isolated from 100,000 g supernatant fraction of Escherichia coli using in vitro primary transcripts of T4 tRNA gene cluster as assay substrates. The endonuclease cleaves the polycistronic RNA precursors into fragments containing monomeric and dimeric stable RNA sequences. The result strongly suggest that this enzyme participates in the early steps of T4 tRNA maturation pathway preceding the action of RNase P.
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PMID:An Escherichia coli endonuclease responsible for primary cleavage of in vitro transcripts of bacteriophage T4 tRNA gene cluster. 625 21

Several DNA fragments carrying tRNA genes have been cloned from EcoRI endonuclease digests of Escherichia coli DNA. Using cloned DNA, the sequence of the region around the distal gene for tRNA1Asp (F(or G)) in the E. coli ribosomal RNA operon [rrnF(or G)] has been determined. In the distal portion of rrnF(or G), the genes for 23S, 5S rRNA and tRNA1Asp (F(or G)) are located in that order and separated by intergenic spacers of 93 and 52 base pairs, respectively. A possible hairpin structure, with its center between the 22nd and 23rd base pair downstream from the 3'-end of the tRNA1Asp(F(or G)) gene, followed by a sequence of eight thymidine residues was identified as the transcription termination signal for rrnF(or G). The termination is rho-independent, at least in vitro, and occurs within the region of the contiguous thymidine residues. A possible promoter for a protein gene is present about 50 base pairs downstream from the rrnF(or G) terminator.
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PMID:Sequence of the distal tRNA1Asp gene and the transcription termination signal in the Escherichia coli ribosomal RNA operon rrnF(or G). 625 18

The Eco RI endonuclease and methylase recognize the same hexanucleotide substrate sequence. We have determined the sequence of a fragment of DNA which encodes these enzymes using the chain-termination method of Sanger (Sanger, F., Nicklen, S., and Coulson, A. R. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 5463-5467). The amino acid sequences of both enzymes were derived from the DNA sequence. The coding regions selected include the only open translational frames of sufficient length to accommodate the enzymes. They coincide with previously established gene boundaries and orientation. The predicted amino acid sequences correlate well with analyses of the purified protein. Comparison of the nucleotide and protein sequences reveals no homology between the endonuclease and methylase which might provide insight into the origin of the restriction-modification system or the mechanism of common substrate recognition. Based on secondary structure predictions, the two enzymes also have grossly different molecular architecture. The base composition of the sequence is 65% A + T, and the codon usage is significantly different from that observed in several Escherichia coli chromosomal genes. In some cases, frequently selected codons are recognized by minor tRNA species. A spontaneous mutation in the endonuclease gene was isolated. Serine replaces arginine at residue 187. In crude extracts, Eco RI specific cleavage is approximately 0.3% wild type.
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PMID:Sequence analysis of the DNA encoding the Eco RI endonuclease and methylase. 625 3

An endonuclease has been purified more than 300-fold from Escherichia coli infected with bacteriophage T4. The enzyme degrades rapidly sedimenting (greater than 1000 S) DNA in vitro by introducing a limited number of breaks. The substrate is the replicative DNA isolated from cells infected with gene-49-defective phage [Kemper, B, and Janz, E. (1976) J. Virol. 18, 992-999]. Molecules of approximately a third the size of unit-length T4 DNA are exclusively found in a limit digest. The enzyme also reacts with single-stranded DNA from various sources. Heat-denatured T4 DNA is converted into acid-soluble oligonucleotides. Circular single-stranded M13 DNA is linearized by endonucleolytic cleavage causing a reduction of infectivity during transfection. The enzyme behaves like a typical late-gene product. Its activity is 100-fold reduced in cells infected with gene-55-defective phage (defect in expression of late functions). A 30-fold reduction in its specific activity was found in cells infected with gene-49-defective phage suggesting that gene 49 codes for the enzyme or controls its expression. The purified enzyme binds to native or denatured DNA from various sources. The protein has a molecular weight of 42000 as determined by gel filtration and sedimentation analysis. Optimal activity on rapidly sedimenting DNA is obtained at pH 8.6 in Tris/HCl buffer in the presence of 10 mM MgCl2. Some 75% of the activity can be obtained with 7 mM MnCl2. 5 mM CaCl2 has a stimulatory effect on the reaction with MgCl2 or MnCl2 each present at its individual optimal concentration. The enzyme does not require the addition of sulfhydryl reagent for full activity. The reaction can be inhibited by compounds like KCl, spermidine, p-hydroxymercuribenzoate or tRNA.
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PMID:Studies on T4-head maturation. 1. Purification and characterization of gene-49-controlled endonuclease. 626 77


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