Human U1 RNA genes contain an unusually sensitive nuclease S1 cleavage site within the conserved 3' flanking region.
Human U1 RNA genes contain an unusually sensitive nuclease S1 cleavage site within the conserved 3' flanking region.
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人类 U1 RNA 基因在保守的 3 侧翼区域内含有异常敏感的核酸酶 S1 切割位点。
DOI：
10.1073/pnas.81.23.7288
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发表时间：
1984
影响因子：
11.1
通讯作者：
Dahlberg,JE
中科院分区：
文献类型：
--
作者：
Htun,H;Lund,E;Dahlberg,JE
我们发现人类U1小核RNA基因的克隆DNA包含两个核酸酶S1敏感位点，一个位于U1 RNA编码区下游约1.8 kb，另一个位于上游约0.3 kb。下游位点对核酸酶异常敏感，在线性和负超螺旋 DNA 中都会被切割。在较低的 pH 值和较低的 NaCl 浓度下，该位点的裂解程度会增强；盐对线性 DNA 的影响比对超螺旋 DNA 的影响更明显。该下游位点的核酸酶 S1 敏感性取决于序列 (dC-dT)n X (dA-dG)n 的存在，其中 n = 15-25。 （n = 5 的一个基因对该区域的核酸酶 S1 切割具有抵抗力。）相反，编码区上游的核酸酶 S1 位点仅在 DNA 超螺旋时才会被切割。该位点在 DNA 链中也存在同型嘧啶 X 同型嘌呤偏向，但序列不太规则。在这些研究过程中，我们发现一些 U1 RNA 基因的限制图谱与其他人发表的限制图谱之间存在一些差异。我们的图谱表明，所有七个克隆的人类 U1 RNA 基因在 U1 RNA 编码区下游 2.3 KB 的序列上非常相似。
We find that the cloned DNAs of human U1 small nuclear RNA genes contain two nuclease S1-sensitive sites, one about 1.8 kilobases downstream of the U1 RNA coding region and the other around 0.3 kilobase upstream. The downstream site is unusually sensitive to the nuclease, being cleaved in both linear and negatively supercoiled DNAs. The extent of cleavage at this site is enhanced at lower pH and reduced concentrations of NaCl; the effects of salt are more apparent on linear than supercoiled DNAs. The nuclease S1 sensitivity of this downstream site is dependent on the presence of the sequence (dC-dT)n X (dA-dG)n, where n = 15-25. (One gene with n = 5 is resistant to nuclease S1 cleavage in this region.) In contrast, the nuclease S1 site upstream of the coding region is cleaved only when the DNA is supercoiled. This site also has a homopyrimidine X homopurine bias in the DNA strands, but the sequence is less regular. In the course of these studies, we detected several discrepancies between our restriction maps of some U1 RNA genes and those published by others. Our maps demonstrate that all seven cloned human U1 RNA genes are very similar in sequence for as much as 2.3 kilobases downstream of the U1 RNA coding region.