Surface histidine residue of archaeal histone affects DNA compaction and thermostability
Surface histidine residue of archaeal histone affects DNA compaction and thermostability
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DOI：
10.1016/s0378-1097(03)00358-6
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发表时间：
2003-07-15
影响因子：
2.1
通讯作者：
Fujiwara, S
中科院分区：
文献类型：
--
作者：
Higashibata, H;Siddiqui, MA;Fujiwara, S
古菌组蛋白只具有真核生物组蛋白的核心结构域部分，它通过与DNA结合来诱导DNA紧致。基于结构模型，二聚体-二聚体相互作用形成四聚体需要在组氨酸和天冬氨酸之间形成两个分子间离子对。为了研究离子对在DNA紧凑中的作用，构建了突变的组蛋白，并以Kodakarasis热球菌KOD1的HpkB为模型蛋白进行了分析。HpkB-H50A、HpkB-H50V和HpkB-H50G分别用丙氨酸、Val和Gly取代保守表面，构建了突变体HpkB-H50A、HpkB-H50V和HpkB-H50G。圆二色谱分析表明，野生型和突变型在结构上没有显著差异。凝胶迁移率改变分析表明，所有突变体都具有与DNA结合的能力，与野生型HpkB相似，但所有突变体对DNA的紧凑效率都低于野生型。此外，所有突变体都不能保持80℃以上的核小体结构(致密DNA)。这些结果表明，His和Asp之间的表面离子对在高温下维持核小体结构和DNA稳定起着重要作用。(C)2003年欧洲微生物学会联合会。爱思唯尔科学公司出版。版权所有。
Archaeal histone, which possesses only the core domain part of eukaryal histone, induced DNA compaction by binding to DNA. Based on structural modeling, tetramer formation by dimer-dimer interaction is considered to require two intermolecular ion pairs formed between histidine and aspartate. To examine the role of the ion pairs on DNA compaction, mutant histones were constructed and analyzed using HpkB from Thermococcus kodakaraensis KOD1 as a model protein. The mutant histones, HpkB-H50A, HpkB-H50V, and HpkB-H50G were constructed by replacing conserved surface His50 with Ala, Val, and Gly, respectively. Circular dichroism analysis indicated no significant difference between wild-type and mutants in their structures. Gel mobility shift assays showed that all mutants possessed DNA binding ability, like wild-type HpkB, however all mutants compacted DNA less efficiently than the wild-type. Moreover, all mutants could not maintain the nucleosome-like structure (compacted form of DNA) above 80degreesC. These results suggest that surface ion pairs between His and Asp play an important role in maintenance of nucleosome structure and DNA stabilization at high temperature. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.