Functional characterization of human nucleosome assembly protein 1-like proteins as histone chaperones
Functional characterization of human nucleosome assembly protein 1-like proteins as histone chaperones
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DOI：
10.1111/j.1365-2443.2009.01361.x
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发表时间：
2010-01-01
期刊：
影响因子：
2.1
通讯作者：
Nagata, Kyosuke
中科院分区：
文献类型：
--
作者：
Okuwaki, Mitsuru;Kato, Kohsuke;Nagata, Kyosuke
核小体组装蛋白1(NAP1)是一种高度保守的组蛋白伴侣蛋白，可能参与了组蛋白H_2A-H_2B异源二聚体的动态调节。然而，NAP1样蛋白的确切作用机制目前尚不清楚。在这项工作中，我们鉴定了两个人类NAP1样蛋白hNAP1L1和hNAP1L4的生化性质，包括一个以前未鉴定的亚型，目的是确定它们的确切机制。HNAP1L1和hNAP1L4主要定位于细胞质，有少量分布于胞核。生化分析表明，hNAP1L1和hNAP1L4均参与了核小体的形成。此外，hNAP1L1具有显著高于hNAP1L4的核小体分解活性，提示hNAP1L1和hNAP1L4可能在组蛋白动力学的调节中发挥不同的作用。在这一初步发现的基础上，我们还发现组蛋白H_2A-H_2B和各种组蛋白H_2A变体-H_2B二聚体在细胞提取液中都与hNAP1L1和hNAP1L4相关联。这些结果表明，人类类NAP1蛋白在组蛋白H_2A-H_2B或H_2A变异体-H_2B二聚体在染色质上的运输和沉积中起重叠作用，而在核小体分解中不起重叠作用。
Nucleosome Assembly Protein 1 (NAP1) is a highly conserved histone chaperone protein suspected to be involved in the dynamical regulation of the histone H2A-H2B hetero-dimer. However, the exact mechanism by which NAP1-like proteins act is currently unknown. In this work, we characterized the biochemical properties of two human NAP1-like proteins, hNAP1L1 and hNAP1L4, including a previously uncharacterized subtype, with the aim of determining their exact mechanistic role. Both hNAP1L1 and hNAP1L4 were found to be localized mainly to the cytoplasm and a minor population of them was suggested to be in the nucleus. Biochemical analyses demonstrated that both hNAP1L1 and hNAP1L4 mediated nucleosome formation. In addition, hNAP1L1 was shown to possess a significantly greater nucleosome disassembly activity than hNAP1L4, suggesting that hNAP1L1 and hNAP1L4 may play distinct roles in the regulation of histone dynamics. Building upon this initial discovery we also found that histone H2A-H2B and various histone H2A variants-H2B dimers were found to associate with both hNAP1L1 and hNAP1L4 in cell extracts. These results suggest that human NAP1-like proteins play overlapping roles in transport and deposition of histone H2A-H2B or H2A variants-H2B dimers on chromatin and nonoverlapping roles in nucleosome disassembly.