DNase-sensitive chromatin structure near a chromosomal origin of bidirectional replication of the avian alpha-globin locus.
DNase-sensitive chromatin structure near a chromosomal origin of bidirectional replication of the avian alpha-globin locus.
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禽类 α 球蛋白基因座双向复制染色体起源附近的 DNA 酶敏感染色质结构。
DOI：
10.1089/dna.1993.12.703
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发表时间：
1993
影响因子：
3.1
通讯作者：
Leffak,M
中科院分区：
文献类型：
--
作者：
Berberich,S;Leffak,M
我们用体外核溢流复制法分析了禽α-珠蛋白基因5′端13 kb区域的复制方向。本实验室以前的工作表明，5日龄鸡红细胞和禽MSB细胞的α-珠蛋白基因在体内以转录方向复制，可能来自απ-珠蛋白基因附近的染色体起源。在这里，我们通过显示复制叉从α-珠蛋白5′-侧翼DNA的8-kb区域发散移动来扩展这些研究。在这两种细胞类型中，双向复制起始的一个潜在区域位于απ-珠蛋白基因5′端约2.5 kb处。此外，复制叉运动的障碍，这可能是位于第二个起源区，被发现约5 kb的上游。在5天红细胞（α-珠蛋白基因表达）和MSB细胞（α-珠蛋白基因不表达）中，在απ-珠蛋白基因5′端约5 kb处（假定的复制起始结构域）发现了DNase I超敏结构。另一个DNase I超敏感位点被证实存在于5日龄红细胞核中转录的απ-珠蛋白基因上游。这些结果表明，α-珠蛋白基因的复制起始于该位点附近的5′-侧翼DNA，该区域由不同的染色质结构标记。
We used anin vitronuclear run-off replication assay to analyze the direction of replication in a 13-kb region 5′ to the avian α-globin genes. Previous work from this laboratory suggested that the α-globin genes of 5-day chick red blood cells and avian MSB cells replicatein vivoin the transcriptional direction, possibly from a chromosomal origin near the απ-globin gene. Here we extend those studies by showing that replication forks move divergently from an 8-kb region of α-globin 5′-flanking DNA. One potential zone for the initiation of bidirectional replication was located approximately 2.5 kb 5′ to the απ-globin gene in both of these cell types. Additionally, a barrier to replication fork movement, which may be located in a second origin zone, was found approximately 5 kb farther upstream. Both in 5-day RBCs, where the α-globin genes are expressed, and in MSB cells where they are not expressed, DNase I hypersensitive structures were found approximately 5 kb 5′ to the απ-globin gene, in the putative replication initiation domain. Another DNase I hypersensitive site was confirmed to exist in 5-day RBC nuclei upstream of the transcribed απ-globin gene. These results suggest that replication of the α-globin genes initiates in the nearby 5′-flanking DNA of this locus in a region marked by distinct chromatin structures.