Molecular mechanisms of chromatin decondensation mediated by novel histone chaperones

新型组蛋白伴侣介导的染色质解缩的分子机制

• 批准号: 11680686
• 负责人: MATSUMOTO Ken
• 金额: $ 2.5万
• 依托单位: RIKEN
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680686/
• 关键词: chromatin; histone; histpne chaperon; adenovirus; Xenopus; TAF- I

Dynamic remodeling in chromatin structure takes place during early development, represented by sperm chromatin decondensation and pronuclei formation upon fertilization. We found that histone chaperones TAF-I (template activating factor I) and NAP-1 have an activity to mediate decondensation of Xenopus sperm chromatin. TAF-I and NAP-I/TAF-II are highly acidic proteins, which we previously identifiled as host factors required for DNA replication and transcription of adenovirus genome complexed with viral basic proteins. Domain analysis of human TAF-1 revealed that the C-terminal acidic region and the dimerization domain of TAF-lb are both neccssary for the decondensation activity. We detected the b form of TAF-I in Xenopus oocyies and eggs, and the cloning of its cDNA led us to conclude that Xenopus TAF-Ib is capable of mediating. decondensation of the sperm chromatin. TAF-I interacts directiy with sperm-specific basic proteins and removes them from the chromatin. Fufther analysis of the molecular mechanisms revealed that TAF-I remains bound to the decondensed chromatin, of which protein components predominantly consist of core histones H3 and H4.Since TAF-I preferentially binds to histones H3/H4 in solution, we suggest that TAF-I associates with the chromatin through its interaction with histone H3/H4.Continuous search for other host faetors that remodel adenovirus genome idenufied B23 protein as a novel template activating factor. We showed that B23/TAF-III also mediates Xenopus sperm chromatin decondensation, dependent on its acidic regions. These results suggest that histone chaperones such as TAF-I and NAP-I play roles in remodeling higher-order chromatin structure as wen as nucleosomal structure through direct interaction with chromatin basic proteins.

染色质结构的动态重塑发生在发育早期，表现为精子染色质解缩和受精后形成原核。我们发现组蛋白伴侣蛋白TAF-I(模板激活因子I)和NAP-1具有介导非洲爪哇精子染色质解聚的活性。Taf-I和NAP-I/TAF-II是高度酸性的蛋白质，是腺病毒基因组与病毒碱性蛋白形成复合体进行DNA复制和转录所必需的宿主因子。人TAF-1的结构域分析表明，TAF-1b的C末端酸性区域和二聚结构域都是解凝活性所必需的。我们在非洲爪哇卵母细胞和卵子中检测到了TAF-I的b型，并克隆了它的cDNA，从而得出了非洲爪哇TAF-Ib具有介导性的结论。精子染色质的解凝集。Taf-I直接与精子特异的碱性蛋白相互作用，并将它们从染色质中移除。进一步的分子机制分析表明，TAF-I仍然与去凝集的染色质结合，其中的蛋白质组分主要由核心组蛋白H3和H4组成。由于TAF-I在溶液中优先与组蛋白H3/H4结合，我们认为TAF-I通过与组蛋白H3/H4的相互作用与染色质结合。继续寻找重构腺病毒基因组识别的B23蛋白的其他宿主因子作为新的模板激活因子。我们发现，B23/TAF-III还依赖于其酸性区域来调节非洲爪哇精子染色质的解凝聚。这些结果表明，组蛋白伴侣蛋白，如TAF-I和NAP-I，通过直接与染色质碱性蛋白相互作用，与核小体结构一样，在高阶染色质结构的重塑中发挥作用。

项目成果

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