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 platelet-derived growth factor (PDGF) A-chain gene is expressed in a tissue- and developmental stage-specific manner. Here we identify an S1 nuclease sensitive region within the first intron that functions as a negative regulatory element in HeLa but not in human glioblastoma (A172) cells in transient transfection assays. A 147 bp DNA fragment that contains this element functions in a position and orientation independent manner to negatively regulate both the PDGF A-chain promoter and the heterologous herpes simplex virus thymidine kinase (TK) promoter. The cell-type specific effect of this 147 bp DNA fragment is seen when it is located downstream but not upstream of the reporter gene driven by either the PDGF A-chain or TK promoters. The negative regulatory element has been localized to a 24 bp DNA sequence within the S1 sensitive site that retains negative regulatory activity and recognizes a nuclear protein in HeLa but not in A172 cells. Furthermore, the 24 bp element functions as a cell type-specific negative element independent of its position. These results suggest that a functional silencer within the first intron exhibits a non-B-form DNA structure under superhelical stress in vitro and may contribute to the cell type-specific transcriptional regulation of PDGF A-chain gene in vivo.
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PMID:An S1 nuclease-sensitive region in the first intron of human platelet-derived growth factor A-chain gene contains a negatively acting cell type-specific regulatory element. 812 85

Three transcripts from the terminal repeat of the channel catfish virus (CCV; also known as ictalurid herpesvirus 1) genome were mapped by S1 nuclease and primer extension analyses as well as by cDNA sequencing. These transcripts, TR3, TR5/6, and TR6, are encoded by open reading frame (ORF) 3, ORFs 5 and 6, and ORF 6, respectively, and correspond to those previously identified by sequence analysis (A. J. Davison, Virology 186:9-14, 1992). ORF 5 has previously been determined to encode thymidine kinase, but ORF 3 and ORF 6 encode proteins of unknown function. Although all three transcripts accumulate to high levels in cells infected in the presence of cycloheximide, kinetic analysis demonstrates that TR5/6 and TR6 are either early or late transcripts that leak through the cycloheximide block. In addition, two transcripts from the terminal repeat of the CCV genome that were mapped previously and were thought to be immediate-early in character, TR8a/9 and TR9, exhibit kinetics characteristic of early or late transcripts. TR3 is an immediate-early transcript that appears to have a very short half-life. In the 3' untranslated region of TR3, there are three copies of an AU-rich element which has previously been shown to be involved in destabilization of the oncogene c-fos and granulocyte/macrophage colony-stimulating factor mRNAs. mRNA destabilization may represent another mechanism by which herpesviruses regulate the rapid switch in expression from immediate-early genes to early genes during the transition to the early phase of infection.
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PMID:Expression kinetics and mapping of the thymidine kinase transcript and an immediate-early transcript from channel catfish virus. 955 75

Transcription of mouse mammary tumor virus (MMTV) DNA is stimulated by steroid hormones. To determine the DNA sequences involved in this regulation, we constructed a plasmid containing the MMTV long terminal repeat (LTR) in front of the coding region of the herpes simplex thymidine kinase gene, from which the promoter had been removed. Portions of the LTR were removed by the nuclease Ba/31, and the deleted molecules were recloned and tested for transcriptional activity in transfections of Ltk-aprt- cells. Stably transfected cell clones were selected and hormone-dependent transcription from the MMTV promoter was studied by the S1 nuclease mapping method. The results show that DNA sequences between -105 and -204 base pairs upstream from the initiation site of viral transcription are required for glucocorticoid stimulation.
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PMID:Glucocorticoid regulation of mouse mammary tumor virus: identification of a short essential DNA region. 1087 40

The equine herpesvirus 1 (EHV-1) homolog of the herpes simplex virus type 1 (HSV-1) tegument phosphoprotein, alphaTIF (Vmw65; VP16), was identified previously as the product of open reading frame 12 (ORF12), was shown to trans-activate immediate-early (IE) gene promoters, and was described as a 60-kDa virion component designated ETIF. However, the ETIF promoter region and transcription initiation site were not identified. The poly(A) signal of the gene 11 (UL49 homolog) lies just upstream of the first ETIF translation initiation codon, indicating that the first ATG may not be used for initiating ETIF translation. Another in-frame translation initiation codon (ATG2) is located 88 bp downstream of the first ETIF initiation codon (ATG1). Western blot analysis showed that the expressed ETIF protein migrated in SDS-PAGE with an apparent molecular mass of approximately 56 kDa, the same molecular weight identified in SDS-PAGE analysis of the KyD EHV-1 virion preparations. The ETIF expression vector pCETIF, which contains ATG2, trans-activated the IE promoter more efficiently than the pC12 containing both ATG1 and ATG2. S1 nuclease analyses mapped the 5' initiation site of the 1.4-kb transcript approximately 17 to 21 nt downstream of the ATG1. The nucleotide sequence upstream of the ATG1 did not have any promoter activity, while the nucleotide sequence upstream of the ATG2 had promoter activity. In transient transfection assays, the pETIFM2 vector, which was mutated in the ATG2, did not trans-activate the IE promoter; however, the pETIFM1 vector, which was mutated in the ATG1, trans-activated the IE promoter. These results demonstrated that the ATG2 of the ETIF ORF is the ETIF translation initiation codon. ETIF trans-activated only the IE promoter, not early (EICP0, EICP22, EICP27, and thymidine kinase) or late (IR5) promoters, confirming that EICP0, EICP22, and EICP27 are early genes.
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PMID:Molecular characterizations of the equine herpesvirus 1 ETIF promoter region and translation initiation site. 1144 76

We have systematically varied microsatellite sequence composition to determine the effects of repeat unit size, G+C content, and DNA secondary structure on microsatellite stability in human cells. The microsatellites were inserted in frame within the 5' region of the herpes simplex virus thymidine kinase (HSV-tk) gene. The polypyrimidine/polypurine microsatellites displayed enhanced S1 nuclease sensitivity in vitro, consistent with the formation of non-B-form DNA structures. Microsatellite mutagenesis studies were performed with a shuttle vector system in which inactivating HSV-tk mutations are measured after replication in a nontumorigenic cell line. A significant increase in the HSV-tk mutation frequency per cell generation was observed after insertion of [TTCC/AAGG]9, [TTTC/AAAG]9, or [TCTA/AGAT]9 sequences (P <or= 0.0002), relative to the HSV-tk gene control. We observed that the G + C content of the microsatellite may affect mutagenesis, as the mean microsatellite mutation rates of the [TTTC/AAAG]9 and [TCTA/AGAT]9 alleles were sevenfold and 11-fold higher, respectively, than the [TTCC/AAGG]9 allele. A bias toward expansion mutations was noted for the majority of clones bearing the [TTCC/AAGG]9 allele as well as a [TC/AG]17 microsatellite of similar allele length. The mean microsatellite mutation rate of the [TTCC/AAGG]9 allele did not differ significantly from that for a [TC/AG]11 allele, demonstrating that these tetranucleotide and dinucleotide alleles are of equivalent stability. It is known that microsatellite mutagenesis is affected by the number of repeat units within an allele. Our data suggest that additional biochemical factors may regulate both the rate and specificity of somatic cell microsatellite mutagenesis.
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PMID:Mutation rate and specificity analysis of tetranucleotide microsatellite DNA alleles in somatic human cells. 1211 8


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