TRANSITION OF A CLONED D(AT)N-D(AT)N TRACT TO A CRUCIFORM INVIVO
TRANSITION OF A CLONED D(AT)N-D(AT)N TRACT TO A CRUCIFORM INVIVO
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DOI：
10.1093/nar/13.12.4343
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发表时间：
1985-01-01
影响因子：
14.9
通讯作者：
PULLEYBLANK, DE
中科院分区：
文献类型：
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作者：
HANIFORD, DB;PULLEYBLANK, DE
一个34个碱基对的简单重复二核苷酸d（AT）n-d（AT）n片段克隆到一个2.4 kb的多接头质粒载体中，在负超螺旋卷曲反应中发生结构转变。该转变的特征在于二维凝胶电泳，S1，P1和T7核酸内切酶1敏感位点的映射，和映射的溴乙醛修饰敏感的位点。在S1核酸酶处理后，可以捕获在回文中心附近的一条或两条链上有切口的超螺旋种类。这些数据表明d（AT）n-dAT）n插入物采用的交替状态是十字形而不是Z构象。与其它B-十字形跃迁不同，d（AT）n-d（AT）n的跃迁具有较低的活化能，镁离子的存在促进了该跃迁。体内拓扑异构体分布的证据表明，在蛋白质合成受阻的条件下，d（AT）n-d（AT）n插入物在E.杆菌
A 34 base pair tract of the simple repeating dinucleotide d(AT)n-d(AT)n cloned into a 2.4 kb polylinker plasmid vector undergoes a structural transition in response to negative superhelical coiling. The transition has been characterized by 2 dimensional gel electrophoresis, mapping of Sl, Pl and T7 endonuclease 1 sensitive sites, and mapping of sites that are sensitive to modification by bromoacetaldehyde. After S1 nuclease treatment it is possible to trap supercoiled species that are nicked on one or both strands near the center of the palindrome. These data show that the alternate state adopted by the d(AT)n-dAT)n insert is a cruciform rather than a Z conformation. Unlike other B-cruciform transitions the transition in d(AT)n-d(AT)n has a low activation energy and the transition is facilitated by the presence of magnesium ions. Evidence from in-vivo topoisomer distributions is presented which shows that under conditions of blocked protein synthesis the d(AT)n-d(AT)n insert will spontaneously adopt the cruciform state in-vivo in E. coli