Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of base changes at the fourth position from the 3'-terminus of Escherichia coli initiator tRNAMet has been studied to test the 'discriminator hypothesis' which proposed that the nucleotide in this position might have a role in the specificity of the aminoacylation reaction. E. coli initiator tRNA lacking the 3'-terminal tetranucleotide was prepared by partial digestion with S1 nuclease. To construct tRNA analogs with different bases in the fourth position this truncated tRNA was joined by RNA ligase to each of four chemically synthesized 2',3'-ethoxy-methylidene tetranucleotides pACCA(em), pCCCA(em), pGCCA(em), and pUCCA(em). In vitro aminoacylation studies showed that all four molecules accepted methionine, albeit with different Vmax values.
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PMID:E. coli initiator tRNA analogs with different nucleotides in the discriminator base position. 629 8

Escherichia coli glycyl-tRNA synthetase is one of two aminoacyl-tRNA synthetases which is comprised of two different subunits (in an alpha 2 beta 2 structure). The two coding regions occur in tandem in the order alpha + beta and are synthesized from a single mRNA (Keng, T., Webster, T. A., Sauer, R. T., and Schimmel, P. R. (1982) J. Biol. Chem. 257, 12503-12508). Primary structures of both proteins were determined by DNA sequencing of each coding region and by analysis of tryptic fragments of the enzyme. The alpha-subunit is 303 codons and terminates with TAA; the beta-subunit is 689 codons followed by tandem TAA stops. S1 nuclease mapping of the 3'-end of the two-cistron glyS mRNA showed that it predominantly ends 33/34 bases beyond the tandem stops with an RNA polymerse terminator sequence. Altogether, 43% of the translated polypeptide sequences were confirmed by mass spectrometric analysis of peptide fragments including confirmation of the COOH-terminal end of the beta-chain. This involved determinations, by fast atom bombardment mass spectrometry, of the masses of numerous whole tryptic fragments (with an accuracy of better than 1 Da) and of fragments truncated by one to three cycles of Edman degradations. The primary structures of the two subunits show no homologies with each other and have no internal sequence repeats of significance. While there are no extensive homologies with five other sequenced, or partially sequenced, synthetases, the alpha-subunit has a short sequence which can be aligned with sequences found in functionally important areas of two other synthetases and in uncharacterized parts of a third and fourth synthetase.
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PMID:Primary structures of both subunits of Escherichia coli glycyl-tRNA synthetase. 630 9

We characterize a 1.95 kb transcription product of the Euglena gracilis chloroplast DNA fragment Eco-N + Q by S1 nuclease analysis and DNA sequencing and show that it is the product of three splicing events. Exon 1 (0.45 kb), exon 2 (0.74 kb) and 175 nucleotides of exon 3 (0.53 kb) code for the chloroplast elongation factor protein (EF-Tu). The remaining part of exon 3 and exon 4 (0.23 kb) have unidentified open reading frames. The chloroplast EF-Tu protein has 408 aminoacids and is to 70% homologous with the E. coli EF-Tu protein. The active site for aminoacyl-tRNA binding is highly conserved, while the active site for GTP/GDP binding lacks the cysteine present in the E. coli EF-Tu protein. The two introns separating exons 1, 2 and 3 are, respectively, 103 and 110 nucleotides long. The size of the third intron is not yet determined. The splicing rules for eukaryote mRNA are not followed.
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PMID:Nucleotide sequence of a Euglena gracilis chloroplast genome region coding for the elongation factor Tu; evidence for a spliced mRNA. 631 May 19

The nucleotide sequence of the cytochrome oxidase subunit 2 (COX2) gene has been obtained from cloned mitochondrial DNA segments of Neurospora crassa. The coding sequences have been identified on the basis of protein sequence homology with the subunit 2 of cytochrome oxidase from yeast and man. The postulated precursor of the N. crassa subunit 2 protein is 250 amino acids long, with a molecular weight of 28,700. As in the tRNA and rRNA genes, the subunit 2 gene is flanked by G + C-rich palindromic sequences, which are highly conserved in N. crassa mitochondria. Three major transcripts have been detected by Northern blot hybridization. A transcript of 1100 bases is tentatively considered the fully processed mRNA. Furthermore, S1 nuclease protection experiments have revealed that the putative subunit 2 mRNA has a 330 nucleotide long 5' leader sequence.
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PMID:Cytochrome oxidase subunit 2 gene in Neurospora crassa mitochondria. 631 89

Subunit 9 of ATPase is known to be encoded in the oli1 gene of yeast mitochondrial DNA. The oli1 transcripts of wild type and of a cytoplasmic "petite" mutant have been analyzed by hybridization of mitochondrial RNA to various DNA fragments from the internal and flanking regions of the gene and by S1 nuclease mapping of the 5' and 3' ends. The results of such studies indicate that the ATPase gene is co-transcribed with the downstream serine tRNA gene. The oli1 message and tRNA are generated by post-transcriptional processing. Two of the nucleolytic processing steps are blocked in the cytoplasmic petite mutant, resulting in the accumulation of several different intermediate transcripts containing both genes. Processing of the 3' ends occurs near a common seven-nucleotide sequence (5'-ATTCTTA-3') also found in the 3' regions of other mitochondrial genes. This sequence is proposed to be part of a signal necessary for either termination of transcription or RNA processing.
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PMID:oli1 Transcripts in wild type and in a cytoplasmic "petite" mutant of yeast. 631 19

We have sequenced a methionine tRNA from mosquito mitochondria, and examined its structure using nucleases S1 and T1 under non-denaturing conditions. The sequence is highly homologous to a putative initiator methionine tRNA gene from Drosophila mitochondria. Its anticodon stem contains a run of three G-C base pairs that is characteristic of conventional initiator tRNAs; however, nuclease S1 analysis suggested an anticodon loop configuration characteristic of conventional elongator tRNAs. We propose that this tRNA can assume both initiator and elongator roles.
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PMID:Sequence and structure of a methionine transfer RNA from mosquito mitochondria. 632 14

Alkylation in beef tRNATrp of phosphodiester bonds by ethylnitrosourea and of N-7 in guanosines and N-3 in cytidines by dimethyl sulfate and carbethoxylation of N-7 in adenosines by diethyl pyrocarbonate were investigated under various conditions. This enabled us to probe the accessibility of tRNA functional groups and to investigate the structure of tRNATrp in solution as well as its interactions with tryptophanyl-tRNA synthetase. The phosphate reactivity towards ethylnitrosourea of unfolded tRNA was compared to that of native tRNA. The pattern of phosphate alkylation of tRNATrp is very similar to that found with other tRNAs studied before using the same approach with protected phosphates mainly located in the D and T psi arms. Base modification experiments showed a striking similarity in the reactivity of conserved bases known to be involved in secondary and tertiary interactions. Differences are found with yeast tRNAPhe since beef tRNATrp showed a more stable D stem and a less stable T psi stem. When alkylation by ethylnitrosourea was studied with the tRNATrp X tryptophanyl-tRNA synthetase complex we found that phosphates located at the 5' side of the anticodon stem and in the anticodon loop were strongly protected against the reagent. The alkylation at the N-3 position of the two cytidines in the CCA anticodon was clearly diminished in the synthetase X tRNA complex as compared with the modification in free tRNATrp; in contrast the two cytidines of the terminal CCA in the acceptor stem are not protected by the synthetase. The involvement of the anticodon region of tRNATrp in the recognition process with tryptophanyl-tRNA synthetase was confirmed in nuclease S1 mapping experiments.
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PMID:Tertiary structure of animal tRNATrp in solution and interaction of tRNATrp with tryptophanyl-tRNA synthetase. 655 32

Various plant viral RNAs possess a 3' terminus with tRNA-like properties. These viral RNAs are charged with an amino acid upon incubation with the cognate aminoacyl-tRNA synthetase and ATP. We have studied the structure of end-labelled 3'-terminal fragments of turnip yellow mosaic virus RNA and brome mosaic virus RNA 2 with chemical modifications of the adenosine and cytidine residues and with enzymatic digestions using RNase T1, nuclease S1 and the double-strand-specific ribonuclease from cobra venom. The data indicate that the 3' termini of these plant viral RNAs lack a cloverleaf structure as found in classical tRNA. The three-dimensional folding, however, reveals a striking resemblance with classical tRNA. The models proposed are supported by phylogenetic data. Apparently distinct three-dimensional solutions have evolved to meet the requirements for faithful recognition by tRNA-specific enzymes. The way in which the aminoacyl acceptor arms of these tRNA-like structures are constructed reveal novel features in RNA folding which may have a bearing on the secondary and tertiary structures of RNA in general. The dynamic behaviour of brome mosaic virus RNA 2 in solution presumably is illustrative of conformational transitions, which RNAs generally undergo on changing the ionic conditions.
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PMID:Three-dimensional models of the tRNA-like 3' termini of some plant viral RNAs. 662 63

We have analyzed a cloned beta O-thalassemia (beta O-thal) gene from a patient doubly heterozygous for hemoglobin Lepore and beta O-thalassemia. Studies of 3H-uridine incorporation into beta-globin mRNA in this patient's erythroblasts suggested an intranuclear defect in both beta and Lepore (delta beta) mRNA synthesis, as did S1 nuclease analysis of nuclear RNA. However, the nucleotide sequence of the beta O-thal gene revealed only a single base change in codon 39 (CAG----UAG), which created a premature translation termination codon. The 5' flanking sequence, including transcription promotor boxes and the mRNA initiation (CAP) site, were normal. The unexpected effect of this mutation on intranuclear beta-mRNA synthesis in vivo was studied by insertion of the cloned gene into a plasmid expression vector and transfection into tissue culture (COS-1) cells. beta-Globin mRNA produced by the transfected cells was assessed by S1 nuclease analysis. The beta O-39 thalassemia gene generated five- to tenfold less beta-mRNA than a normal beta-gene in both nuclear and cytoplasmic RNA, simulating the results observed in vivo. Moreover, the small amount of beta O-39 mRNA produced was as stable as normal beta-mRNA during an actinomycin D chase, ruling out rapid cytoplasmic turnover as a cause of the reduced accumulation. Cotransfection of the beta O-39 thalassemia gene with a mutant tyrosine suppressor tRNA gene resulted in restoration of the beta O-39 mRNA accumulation to near-normal levels. On the basis of these results, we suggest that the low levels of beta-mRNA known to exist in the common form of beta O-thalassemia, beta O-39 thalassemia, result from a lesion in transcription, or early posttranscriptional processes; the defect appears to be corrected by restoration of proper translational potential to the mutant mRNA, at least in a gene transfer-expression system in tissue-culture cells.
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PMID:Intranuclear defect in beta-globin mRNA accumulation due to a premature translation termination codon. 673 65

The 3' terminus of TYMV RNA, which possesses tRNA-like properties, has been studied. A 3' terminal fragment of 112 nucleotides was obtained by cleavage with RNase H after hybridization of a synthetic oligodeoxynucleotide to the viral RNA. The accessibility of cytidine and adenosine residues was probed with chemical modification. Enzymatic digestion studies were performed with RNase T1, nuclease S1 and the double-strand specific RNase from the venom of the cobra Naja naja oxiana. A model is proposed for the secondary structure of the 3' terminal region of TYMV RNA comprising 86 nucleotides. The main feature of this secondary structure is the absence of a conventional acceptor stem as present in canonical tRNA. However, the terminal 42 nucleotides can be folded in a tertiary structure which bears strong resemblance with the acceptor arm of canonical tRNA. Comparison of this region of TYMV RNA with that of other RNAs from both the tymovirus group and the tobamovirus group gives support to our proposal for such a three-dimensional arrangement. The consequences for the recognition by TYMV RNA of tRNA-specific enzymes is discussed.
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PMID:The tRNA-like structure at the 3' terminus of turnip yellow mosaic virus RNA. Differences and similarities with canonical tRNA. 707 75


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