The role of intercalating residues in chromosomal high-mobility-group protein DNA binding, bending and specificity
The role of intercalating residues in chromosomal high-mobility-group protein DNA binding, bending and specificity
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DOI：
10.1093/nar/gkg389
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发表时间：
2003-06-01
影响因子：
14.9
通讯作者：
Churchill, MEA
中科院分区：
文献类型：
--
作者：
Klass, J;Murphy, FV;Churchill, MEA
普遍存在的高迁移率群 (HMGB) 染色体蛋白以非序列特异性方式结合 DNA，以促进染色质功能和基因调控。 HMG 结构域的小沟 DNA 结合诱导大量 DNA 向大沟弯曲，并且几个界面残基通过 DNA 插入起作用。系统地研究了一系列突变果蝇 HMGB (HMG-D) 蛋白的插入残基在 DNA 结合、弯曲和特异性中的作用。 HMG-D 的主要嵌入残基 Met13 是高亲和力 DNA 结合和正常 DNA 弯曲所必需的。 Leu9 和 Tyr12 直接与 Met13 相互作用，除了线性 DNA 结合和弯曲之外，它们也是 HMG 结构域稳定性所必需的，这是这些残基的重要功能。相反，在将残基 Val32 和 Thr33 截断为丙氨酸时，DNA 结合和弯曲得以保留，但甘氨酸取代后 DNA 弯曲减少。此外，用预计参与 HMG 结构域转录因子特异性的残基替换插入残基会导致 DNA 亲和力增加并减少 DNA 弯曲，但不会增加特异性。这些研究揭示了支持嵌入残基的残基的重要性，并表明除了少数碱基特异性氢键之外的 HMG 结构域特征区分了序列特异性和非序列特异性 HMG 结构域功能。
Ubiquitous high-mobility-group (HMGB) chromosomal proteins bind DNA in a non-sequence- specific fashion to promote chromatin function and gene regulation. Minor groove DNA binding of the HMG domain induces substantial DNA bending toward the major groove, and several interfacial residues contribute by DNA intercalation. The role of the intercalating residues in DNA binding, bending and specificity was systematically examined for a series of mutant Drosophila HMGB (HMG-D) proteins. The primary intercalating residue of HMG-D, Met13, is required both for high-affinity DNA binding and normal DNA bending. Leu9 and Tyr12 directly interact with Met13 and are required for HMG domain stability in addition to linear DNA binding and bending, which is an important function for these residues. In contrast, DNA binding and bending is retained in truncations of intercalating residues Val32 and Thr33 to alanine, but DNA bending is decreased for the glycine substitutions. Furthermore, substitution of the intercalating residues with those predicted to be involved in the specificity of the HMG domain transcription factors results in increased DNA affinity and decreased DNA bending without increased specificity. These studies reveal the importance of residues that buttress intercalating residues and suggest that features of the HMG domain other than a few base-specific hydrogen bonds distinguish the sequence-specific and non-sequence-specific HMG domain functions.