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A quantitative assay for Xenopus 5S RNA gene transcription in vitro 总被引:37,自引:0,他引:37
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Transcription fraction TFIIIC can regulate differential Xenopus 5S RNA gene transcription in vitro 总被引:30,自引:4,他引:26
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A P Wolffe 《The EMBO journal》1988,7(4):1071-1079
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Assembly of transcriptionally active chromatin in Xenopus oocytes requires specific DNA binding factors 总被引:22,自引:0,他引:22
Active minichromosomes assembled on injected 5S RNA gene clones are stable in Xenopus oocytes; endogenous 5S DNA specific factor(s) are required for their assembly. When somatic-type and oocyte-type 5S RNA gene clones are coinjected, the somatic genes are assembled into active minichromosomes, while most of the oocyte genes are assembled into inactive ones. The differential 5S RNA gene expression, which mimics that in somatic cells, appears to result from titration of 5S DNA specific factor(s) by the competing somatic 5S DNA, followed by histone mediated assembly of inactive chromatin on the oocyte 5S DNA. Stable minichromosomes are also assembled on a cloned histone H4 gene; again, intragenic DNA rearrangements affect the efficiency of assembly of active chromatin and differential gene expression occurs after coinjection of two or more H4 DNA constructs. We suggest that the H4 DNA molecules also compete for limiting quantities of specific DNA binding factor(s) required for the assembly of active H4 gene chromatin. 相似文献
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Oocyte and somatic 5S ribosomal RNA and 5S RNA encoding genes in Xenopus tropicalis. 总被引:2,自引:2,他引:0
W Nietfeld M Digweed H Mentzel W Meyerhof M K?ster W Kn?chel V A Erdmann T Pieler 《Nucleic acids research》1988,16(18):8803-8815
We have investigated the structure of oocyte and somatic 5S ribosomal RNA and of 5S RNA encoding genes in Xenopus tropicalis. The sequences of the two 5S RNA families differ in four positions, but only one of these substitutions, a C to U transition in position 79 within the internal control region of the corresponding 5S RNA encoding genes, is a distinguishing characteristic of all Xenopus somatic and oocyte 5S RNAs characterized to date, including those from Xenopus laevis and Xenopus borealis. 5S RNA genes in Xenopus tropicalis are organized in clusters of multiple repeats of a 264 base pair unit; the structural and functional organization of the Xenopus tropicalis oocyte 5S gene is similar to the somatic but distinct from the oocyte 5S DNA in Xenopus laevis and Xenopus borealis. A comparative sequence analysis reveals the presence of a strictly conserved pentamer motif AAAGT in the 5'-flanking region of Xenopus 5S genes which we demonstrate in a separate communication to serve as a binding signal for an upstream stimulatory factor. 相似文献
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A second and minor DNA component containing 5s RNA genes has been purified from the genomic DNA of Xenopus laevis (XIt 5S DNA). Some of its physical and chemical characteristics are described. It contains a 5S RNA gene sequence which has some oocyte and some somatic-specific residues, as well as nucleotides which differ from both types of 5S RNA. There are about 2000 of these 5S RNA genes per haploid complement of DNA compared to about 24,000 of the principal oocyte 5S RNA genes. The multiple repeating units of XIt 5S DNA are homogeneous in length (about 350 base pairs). We present evidence that XIt 5S RNA is transcribed in ovaries but not in somatic cells; XIt 5S DNA may therefore be under the same control as the major oocyte 5S DNA. 相似文献
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Dominant and specific repression of Xenopus oocyte 5S RNA genes and satellite I DNA by histone H1. 总被引:31,自引:11,他引:20
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A P Wolffe 《The EMBO journal》1989,8(2):527-537
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We have injected circular DNA, labeled with 32P at a single restriction site, into germinal vesicles of Xenopus laevis oocytes in order to study the nucleosome arrangement on the assembled minichromosomes. Two types of genes were used in these studies, the somatic 5 S RNA gene unit of Xenopus borealis and the histone gene unit of Drosophila melanogaster. We find that injections of labeled DNA alone, at 1 ng DNA per oocyte, results in irregularly spaced nucleosomes and partially supercoiled DNA molecules. However, perfectly spaced nucleosomes are assembled and fully supercoiled DNA is recovered if 5 to 20 nanograms of cold vector DNA is coinjected with the labeled DNA. At the optimum chromatin assembly conditions, the nucleosomes are perfectly spaced with a 180 base-pair periodicity, but they are randomly positioned on the DNA. The assembly of a periodic chromatin structure is accompanied by a dramatic enhancement in the expression of the injected 5 S RNA gene. 相似文献
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Differential transcription of Xenopus oocyte and somatic-type 5 S genes in a Xenopus oocyte extract 总被引:10,自引:0,他引:10
L Millstein P Eversole-Cire J Blanco J M Gottesfeld 《The Journal of biological chemistry》1987,262(35):17100-17110