Scott M J, Tsai M J, O'Malley B W
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Biochemistry. 1987 Oct 20;26(21):6831-40. doi: 10.1021/bi00395a037.
The location of CR1 middle repetitive sequences within or near the boundaries of the ovalbumin DNase I sensitive domain has suggested that CR1 sequences may play a role in defining transition regions of DNase I sensitivity in hen oviduct nuclei. We have examined this apparent relationship of CR1 sequences and transitions of chromatin structure by determining the DNase I sensitivity in oviduct nuclei of a 47-kilobase region that contains five CR1 sequences and the transcribed ovomucoid and ovoinhibitor genes. We find that three of the CR1 sequences occur within a broad transition region of decreasing DNase I sensitivity downstream of the ovomucoid gene. Another CR1 is in a region of decreased DNase I sensitivity within the ovoinhibitor gene. The fifth CR1 sequence is in a DNase I sensitive region between the two genes but which is less sensitive to DNase I digestion than the region immediately upstream from the ovomucoid gene. Thus, the CR1 sequences occur within regions of reduced relative DNase I sensitivity, suggesting that CR1s could facilitate the formation of a chromatin conformation that is less sensitive to DNase I digestion. Unexpectedly, the noncoding strand of sequences within and immediately adjacent to the 5' end of the actively transcribed ovomucoid and ovalbumin genes was less sensitive to DNase I digestion than their respective coding strands.
CR1中间重复序列位于卵清蛋白DNA酶I敏感结构域的边界内或附近，这表明CR1序列可能在确定鸡输卵管细胞核中DNA酶I敏感性的过渡区域中发挥作用。我们通过测定一个47千碱基区域的输卵管细胞核中的DNA酶I敏感性，来研究CR1序列与染色质结构转变之间的这种明显关系，该区域包含五个CR1序列以及转录的卵类粘蛋白和卵抑制剂基因。我们发现，其中三个CR1序列出现在卵类粘蛋白基因下游DNA酶I敏感性降低的一个宽泛过渡区域内。另一个CR1位于卵抑制剂基因内DNA酶I敏感性降低的区域。第五个CR1序列位于两个基因之间的一个DNA酶I敏感区域，但对DNA酶I消化的敏感性低于卵类粘蛋白基因紧上游的区域。因此，CR1序列出现在相对DNA酶I敏感性降低的区域内，这表明CR1可能有助于形成对DNA酶I消化不太敏感的染色质构象。出乎意料的是，活跃转录的卵类粘蛋白和卵清蛋白基因5'端内及其紧邻区域的非编码链对DNA酶I消化的敏感性低于它们各自的编码链。
