Conformational changes of DNA induced by binding of Chironomus high mobility group protein 1a (cHMG1a) - Regions flanking an HMG1 box domain do not influence the bend angle of the DNA
Conformational changes of DNA induced by binding of Chironomus high mobility group protein 1a (cHMG1a) - Regions flanking an HMG1 box domain do not influence the bend angle of the DNA
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DOI：
10.1074/jbc.272.32.19763
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发表时间：
1997-08-08
影响因子：
4.8
通讯作者：
Wisniewski, JR
中科院分区：
文献类型：
--
作者：
Heyduk, E;Heyduk, T;Wisniewski, JR
高迁移率族（HMG）蛋白被认为是通过调节DNA构象来促进染色质高级结构的组装。在这项工作中，我们研究了由摇蚊HMG 1（cHMG 1a）和HMGI（cHMGI）蛋白诱导的30个碱基对DNA片段的弯曲。通过监测连接到DNA片段的相对末端的荧光探针之间的端到端距离来测量溶液中的DNA弯曲。使用一种新的铕螯合物作为荧光供体，通过荧光能量转移测量距离。这些测量结果表明，30个碱基对DNA中的端到端距离从游离DNA中的100埃降低到cHMG1a.DNA复合物中的50.5埃。与这些距离测量一致的最可能的DNA弯曲角约为150度。位于cHMG 1a蛋白的HMG 1盒结构域的C末端附近的带电调节结构域的缺失对诱导的弯曲角没有影响。诱导大的DNA弯曲的能力将cHMG 1与cHMGI蛋白区分开来。在结合cHMGI蛋白时，仅观察到DNA构象的小扰动。cHMG 1a的强DNA弯曲活性及其在细胞中的相对丰度表明，该蛋白在染色质结构的调节中起着非常重要的作用。
High mobility group (HMG) proteins are thought to facilitate assembly of higher order chromatin structure through modulation of DNA conformation. In this work we investigate the bending of a 30-base pair DNA fragment induced by Chironomus HMG1 (cHMG1a), and HMGI (cHMGI) proteins. The DNA bending was measured in solution by monitoring the end-to-end distance between fluorescence probes attached to opposite ends of the DNA fragment. The distance was measured by fluorescence energy transfer using a novel europium chelate as a fluorescence donor. These measurements revealed that the end-to-end distance in the 30-base pair DNA was decreased from similar to 100 Angstrom in free DNA to similar to 50.5 Angstrom in cHMG1a.DNA complex. The most probable DNA bending angle consistent with these distance measurements is about 150 degrees. The deletion of the charged regulatory domains located close to the C terminus of the HMG1 box domain of cHMG1a protein had no effect on the induced bend angle. The ability to induce a large DNA bend distinguishes the cHMG1 from the cHMGI protein. Only small perturbation of the DNA conformation was observed upon binding of the cHMGI protein. A strong DNA bending activity of cHMG1a and its relative abundance in the cell suggests that this protein plays a very important role in modulation of chromatin structure.