Multiple non-B-DNA conformations of polypurine.polypyrimidine sequences in plasmids.
Multiple non-B-DNA conformations of polypurine.polypyrimidine sequences in plasmids.
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质粒中多聚嘌呤、多聚嘧啶序列的多种非 B-DNA 构象。
DOI：
10.1021/bi00471a027
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Wells,RD
中科院分区：
文献类型：
--
作者：
Shimizu,M;Hanvey,JC;Wells,RD
摘要：在质粒中具有中心中断的聚嘌呤-聚嘧啶（Pur-Pyr）序列可以采用多种非B-DNA构象，这取决于特定化学探针（0 s 04，焦碳酸二乙酯和硫酸二甲酯）和二维电泳所揭示的条件。相对长的镜像重复Pur-Pyr序列（GAA）9 TTC（GAA）8和（GGA）9 TCC（GGA）8在pH7.0 -6.0时在分离自大肠杆菌的负超螺旋质粒中形成单一的典型分子内三链体。随着pH值的降低和/或负超螺旋化程度的增加，这些序列经历了一种新的构象变化，如焦碳酸二乙酯在聚嘌呤链中间对腺嘌呤的超修饰和Os 04与胸腺嘧啶在聚嘧啶链中心和四分之一点的反应所揭示的。为了评估这种结构，克隆和研究了一个家族的相关Pur-Pyr序列。非镜像重复序列（GGA）9 TCC（GAA）8仅在酸性pH条件下形成非B构象，但结构性质与镜像重复序列不同。此外，当镜像重复序列的中心中断从3个碱基增加到9个碱基时，在pH5.0时[在序列（GAA）9 TTAATTCGC（GAA）8中的（GAA）9和（GAA）8区域]独立地形成两个典型的三链体，因此，如果中断足够长，Pur-Pyr序列的两个半部分不相互作用。新类型的折叠DNA的几何形状，解释这些结果进行了描述。
Revised Manuscript Received January 26, 1990 abstract: A polypurine-polypyrimidine (Pur-Pyr) sequence with a central interruption in a plasmid can adopt multiple non-B-DNA conformations depending on the conditions as revealed by specific chemical probes (0s04, diethyl pyrocarbonate, and dimethyl sulfate) and two-dimensional electrophoresis. The relatively long mirror repeat Pur-Pyr sequences (GAA) 9TTC (GAA) 8 and (GGA) 9TCC (GGA) 8 form single canonical intramolecular triplexes at pH 7.0-6.0 in negatively supercoiled plasmids as isolated from Es-cherichia coli. With a lowering of the pH and/or an increase in the degree of negative supercoiling, these sequences undergo a novel conformational change as revealed by diethyl pyrocarbonate hypermodification of adenines in the middle of the polypurine strand and Os04 reaction with thymines in the center and the quarter points of the polypyrimidine strand. To evaluate this structure, a family of related Pur-Pyr sequences were cloned and studied. The non mirror repeat sequence (GGA) 9TCC (GAA) 8 forms a non-B conformation only under acidic pH conditions, but the structural properties are different from those of the mirror repeat sequences. Furthermore, when the central interruptions of a mirror repeat sequence were increased from 3 to 9 bp, twocanonical triplexes formed independently at pH 5.0 [at the (GAA) 9 and (GAA) 8 regions in the sequence (GAA) 9TTAATTCGC (GAA) 8], Thus, if an interruption is sufficiently long, the two halves of the Pur-Pyr sequence do not interactwith each other. Novel types of folded DNA geometries which explain these results are described.