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)

S1 nuclease mapping of the Psammechinus miliaris embryonic histone mRNAs locates the 5' termini in or adjacent to a short sequence homology (5'pyCATTCpu3') downstream from the putative RNA polymerase II regulatory sequence (5'TATAAATA3') or related sequences. The 3' termini map just after a sequence containing GC-rich hyphenated dyad symmetry, a feature of most known terminator sequences.
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PMID:Sea urchin histone mRNA termini are located in gene regions downstream from putative regulatory sequences. 737 64

In order to examine whether splicing can occur cotranscriptionally in mammalian nuclei, we mapped exon-intron boundaries on nascent RNA chains transcribed by RNA polymerase II. A procedure that allows fractionation of nuclei into a chromatin pellet containing DNA, histones, and ternary transcription complexes and a supernatant containing the bulk of the nonhistone proteins and RNAs that are released from their DNA templates was developed. The transcripts of the genes encoding DBP, a transcriptional activator protein, and HMG coenzyme A reductase recovered from the chromatin pellet and the supernatant were analyzed by S1 nuclease mapping. The large majority of the RNA molecules from the pellet appeared to be nascent transcripts, since, in contrast to the transcripts present in the supernatant, they were not cleaved at the polyadenylation site but rather contained heterogeneous 3' termini encompassing this site. Splicing intermediates could be detected among nascent and released transcripts, suggesting that splicing occurs both cotranscriptionally and posttranscriptionally. Our results also indicate that polyadenylation is not required for the splicing of the last DBP intron. In addition to allowing detailed structural analysis of nascent RNA chains, the physical isolation of nascent transcripts also yields reliable measurements of relative transcription rates.
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PMID:Physical isolation of nascent RNA chains transcribed by RNA polymerase II: evidence for cotranscriptional splicing. 752 61

We have studied the chromatin structure of the Saccharomyces cerevisiae FBP1 gene, which codes for fructose-1,6-bisphosphatase. A strong, constitutive, DNase I, micrococcal nuclease and S1 nuclease hypersensitive site is present close to the 3' end of the coding region. In the repressed state, positioned nucleosomes exist around this site, and subtle changes occur in this nucleosomal organization upon derepression. A DNase I hypersensitive region is located within the promoter between positions -540 and -400 and its extends towards the gene in the derepressed state, leading to an alteration of nucleosomal positioning. Psoralen crosslinking of chromatin, which is used for the first time to study the mobility of restriction fragments from an RNA polymerase II gene, revealed that part of the promoter is nucleosome-free, in accordance with the results of DNase I digestion. A model is presented that, based on the chromatin structure, puts forward the hypothesis that the promoter UAS is located between -540 and -340. Finally, psoralen crosslinking, as well as digestions with micrococcal nuclease or restriction endonucleases suggests that most if not all of the copies of the active FBP1 gene are covered by nucleosomes.
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PMID:Chromatin structure of the yeast FBP1 gene: transcription-dependent changes in the regulatory and coding regions. 810 72

The human beta-globin genes are regulated by the locus control region (LCR), an element composed of multiple DNase I-hypersensitive sites (HS sites) located 5' to the genes. Various functional studies indicate that the LCR confers high-level, position-independent, and copy number-dependent expression to linked globin genes in transgenic mice. However, the structural basis for LCR function is unknown. Here we show that LCR HS sites can be reconstituted in an erythroid cell-specific manner on chromatin-assembled LCR templates in vitro. Surprisingly, HS2 and HS3 are also formed with erythroid proteins in the absence of chromatin assembly, indicating that sensitivity to nucleases is not simply a consequence of nucleosome reorganization. The generation of LCR HS sites in the absence of chromatin assembly leads to the formation of S1- and KMnO(4)-sensitive regions in HS2 and HS3. These sites are also sensitive to S1 nuclease in erythroid cells in vivo, suggesting a distorted DNA structure in the LCR core enhancer elements. Finally, we show that RNA polymerase II initiates transcription in the HS2 and HS3 core enhancer regions in vitro. Transcription in both HS2 and HS3 proceeds in a unidirectional manner. Taken together, the data suggest that erythroid proteins interact with the core enhancer elements, distort the DNA structure, and recruit polymerase II transcription complexes. These results further our understanding of the structural basis for LCR function and provide an explanation for why the LCR core regions are so extremely sensitive to nucleases in erythroid cells.
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PMID:Reconstitution of human beta-globin locus control region hypersensitive sites in the absence of chromatin assembly. 1128 43


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