A variant octamer motif in a Xenopus H2B histone gene promoter is not required for transcription in frog oocytes.
A variant octamer motif in a Xenopus H2B histone gene promoter is not required for transcription in frog oocytes.
复制标题
非洲爪蟾 H2B 组蛋白基因启动子中的变异八聚体基序对于青蛙卵母细胞中的转录不是必需的。
DOI：
10.1128/mcb.11.2.641-654.1991
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发表时间：
1991
影响因子：
5.3
通讯作者：
Perry,M
中科院分区：
文献类型：
--
作者：
Hinkley,C;Perry,M
在第一次减数分裂前的g2中，异卵细胞在没有染色体DNA复制的情况下积累组蛋白mRNA和蛋白质，因此代表了一种有吸引力的生物系统，在该系统中可以检测与细胞周期分离的组蛋白基因表达。先前的研究表明，在卵母细胞中，编码五种主要xenopushistone类的基因的转录起始位点的5 '端200 bp内存在最高转录水平所需的序列。我们通过定点诱变确定了注射卵母细胞中组蛋白H2B基因转录所需的个体调控序列和dna结合蛋白。xenopush2b基因有一个相对简单的启动子，包含几个转录调控元件，包括TFIID、CBP和ATF/CREB结合位点，这些都是最大转录所需的。H2B启动子中的一个序列（CTTTACAT）类似于人类H2B基因细胞周期调控的靶点保守八元基序（ATTTGCAT），在卵母细胞中转录不需要。尽管如此，将一致的八聚体基序替换为变异的八聚体元件可激活H2B转录。卵母细胞因子，可能包括普遍存在的Oct-1因子，特异性地与一致的八聚体基序结合，而不是与变异序列结合。我们的研究结果表明，参与免疫球蛋白基因淋巴特异性表达和哺乳动物H2B组蛋白基因s期特异性激活的转录调控元件可以激活非分裂两栖动物卵母细胞的转录。
Xenopusoocytes, arrested in G2before the first meiotic division, accumulate histone mRNA and protein in the absence of chromosomal DNA replication and therefore represent an attractive biological system in which to examine histone gene expression uncoupled from the cell cycle. Previous studies have shown that sequences necessary for maximal levels of transcription in oocytes are present within 200 bp at the 5′ end of the transcription initiation site for genes encoding each of the five majorXenopushistone classes. We have defined by site-directed mutagenesis individual regulatory sequences and characterized DNA-binding proteins required for histone H2B gene transcription in injected oocytes. TheXenopusH2B gene has a relatively simple promoter containing several transcriptional regulatory elements, including TFIID, CBP, and ATF/CREB binding sites, required for maximal transcription. A sequence (CTTTACAT) in the H2B promoter resembling the conserved octamer motif (ATTTGCAT), the target for cell-cycle regulation of a human H2B gene, is not required for transcription in oocytes. Nonetheless, substitution of a consensus octamer motif for the variant octamer element activates H2B transcription. Oocyte factors, presumably including the ubiquitous Oct-1 factor, specifically bind to the consensus octamer motif but not to the variant sequence. Our results demonstrate that a transcriptional regulatory element involved in lymphoid-specific expression of immunoglobulin genes and in S-phase-specific activation of mammalian H2B histone genes can activate transcription in nondividing amphibian oocytes.