Department of Biological Science and Environment, Graduate School of Humanities and Sciences, Nara Women's University, Kitauoya-nishi-machi, Nara 630-8506, Japan.
Cell Biol Int. 2013 Jul;37(7):748-54. doi: 10.1002/cbin.10091. Epub 2013 Apr 11.
The core histone proteins (H2A, H2B, H3 and H4) are nuclear-localised proteins that play a central role in the formation of nucleosome structure. They have long been considered to be absent from extra-nuclear, DNA-containing organelles; that is plastids and mitochondria. Recently, however, the targeting of core histone H3 to mitochondria, and the presence of nucleosome-like structures in mitochondrial nucleoids, were proposed in cauliflower and tobacco respectively. Thus, we examined whether histone H3 was present in plant organelles and participated in the organisation of nucleoid structure, using highly purified organelles and organelle nucleoids isolated from BY-2 cultured tobacco cells. Immunofluorescence microscopic observations and Western blotting analyses demonstrated that histone H3 was absent from organelles and organelle nucleoids, consistent with the historical hypothesis. Thus, the organisation of organelle nucleoids, including putative nucleosome-like repetitive structures, should be constructed and maintained without participation of histone H3.
核心组蛋白（H2A、H2B、H3 和 H4）是定位于细胞核内的蛋白质，在核小体结构的形成中发挥核心作用。长期以来，人们一直认为它们不存在于含有 DNA 的核外细胞器中；即质体和线粒体。然而，最近在花椰菜和烟草中分别提出了核心组蛋白 H3 靶向线粒体以及线粒体类核中存在核小体样结构的观点。因此，我们使用高度纯化的细胞器和从 BY-2 培养的烟草细胞中分离的细胞器类核来研究组蛋白 H3 是否存在于植物细胞器中并参与类核结构的组织。免疫荧光显微镜观察和 Western blot 分析表明，组蛋白 H3 不存在于细胞器和细胞器类核中，与历史假说一致。因此，细胞器类核的组织，包括假定的核小体样重复结构，应该在没有组蛋白 H3 参与的情况下构建和维持。
