Nucleosome assembly protein-1 is a linker histone chaperone in Xenopus eggs
Nucleosome assembly protein-1 is a linker histone chaperone in Xenopus eggs
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DOI：
10.1073/pnas.0500822102
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发表时间：
2005-06-07
影响因子：
11.1
通讯作者：
Ohsumi, K
中科院分区：
文献类型：
--
作者：
Shintomi, K;Iwabuchi, M;Ohsumi, K
在真核细胞中，基因组DNA主要通过核心和连接蛋白的顺序结合被包装成核小体。被称为组蛋白伴侣蛋白的酸性蛋白与核心组蛋白结合以中和其正电荷，从而促进其正确沉积到DNA上以组装核小体的核心。然而，对于连接子组蛋白，人们对连接子组蛋白沉积到连接子DNA上的调控机制知之甚少。在这里，我们报道，在非洲爪蟾卵中，连接组蛋白与非洲爪蟾核小体组装蛋白-1 （NAP-1）的同源物相关，NAP-1已知是果蝇和哺乳动物细胞中核心组蛋白H2A和H2B的伴侣[Ito， T., Bulger， M., Kobayashi， R. & Kadonaga， J. T. (1996) Mol.细胞生物学，16,312 -3124；张丽丽，罗兰杰，米赞，C.，恩斯特，S. G., Allis， C. D., Annunziato， A. T.（1997）生物化学36,469-480。我们发现，在精子染色质重塑成核小体和连接组蛋白结合核小体核心二聚体的过程中，NAP-1作为连接组蛋白的伴侣。在NAP-1存在的情况下，连接体组蛋白以生理离子强度适当地沉积在连接体DNA上，而不会形成非特异性聚集体。这些结果强烈提示NAP-1在爪蟾卵中作为连接组蛋白的伴侣。
In eukaryotic cells, genomic DNA is primarily packaged into nucleosomes through sequential ordered binding of the core and linker histone proteins. The acidic proteins termed histone chaperones are known to bind to core histones to neutralize their positive charges, thereby facilitating their proper deposition onto DNA to assemble the core of nucleosomes. For linker histones, however, little has been known about the regulatory mechanism for deposition of linker histones onto the linker DNA. Here we report that, in Xenopus eggs, the linker histone is associated with the Xenopus homologue of nucleosome assembly protein-1 (NAP-1), which is known to be a chaperone for the core histones H2A and H2B in Drosophila and mammalian cells [Ito, T., Bulger, M., Kobayashi, R. & Kadonaga, J. T. (1996) Mol. Cell Biol. 16, 3112-3124; Chang, L., Loranger, S. S., Mizzen, C., Ernst, S. G., Allis, C. D. & Annunziato, A. T. (1997) Biochemistry 36,469-480]. We show that NAP-1 acts as the chaperone for the linker histone in both sperm chromatin remodeling into nucleosomes and linker histone binding to nucleosome core dimers. In the presence of NAP-1, the linker histone is properly deposited onto linker DNA at physiological ionic strength, without formation of nonspecific aggregates. These results strongly suggest that NAP-1 functions as a chaperone for the linker histone in Xenopus eggs.