Lee JungHa, Kang Seungmin, Choi Yong Seok, Kim Hong-Kyung, Yeo Chang-Yeol, Lee Yangsin, Roth Jürgen, Lee JooHun
Department of Systems Biology, Yonsei University, Seoul 120-749, Korea.
Department of Life Science and Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Korea.
Protist. 2015 Feb;166(1):1-13. doi: 10.1016/j.protis.2014.11.001. Epub 2014 Nov 29.
During the differentiation of the amoeba Naegleria pringsheimi into a flagellate, a transient complex containing γ-tubulin, pericentrin-like protein, and myosin II (GPM complex) is formed, and subsequently a pair of basal bodies is assembled from the complex. It is not understood, however, how a single GPM is formed nor how the capability to form this complex is acquired by individual cells. We hypothesized that the GPM is formed from a precursor complex and developed an antibody that recognizes Naegleria (Ng)-transacylase, a component of the precursor complex. Immunostaining of differentiating cells showed that Ng-transacylase is concentrated at a site in the amoeba and that γ-tubulin is transiently co-concentrated at the site, suggesting that the GPM is formed from a precursor, GPMp, which contains Ng-transacylase and is already present in the amoeba. Immunostaining of growing N. pringsheimi with Ng-transacylase antibody revealed the presence of one GPMp in interphase cells, but two GPMps in mitotic cells, suggesting that N. pringsheimi maintains one GPMp per cell by duplicating and segregating the complex according to its cell cycle. Our results demonstrate the existence of a cell cycle-dependent duplicating complex that provides a site for the de novo assembly of the next generation of basal bodies.
在阿米巴原虫普氏耐格里变形虫分化为鞭毛虫的过程中，会形成一种包含γ-微管蛋白、中心粒外周蛋白样蛋白和肌球蛋白II的瞬时复合物（GPM复合物），随后从该复合物组装出一对基体。然而，目前尚不清楚单个GPM复合物是如何形成的，也不清楚单个细胞是如何获得形成这种复合物的能力的。我们推测GPM复合物由前体复合物形成，并开发了一种识别前体复合物成分耐格里变形虫（Ng）-转酰基酶的抗体。对分化细胞的免疫染色显示，Ng-转酰基酶集中在变形虫的一个位点，γ-微管蛋白也瞬时共集中在该位点，这表明GPM复合物由前体GPMp形成，GPMp包含Ng-转酰基酶且已存在于变形虫中。用Ng-转酰基酶抗体对生长中的普氏耐格里变形虫进行免疫染色，发现在间期细胞中有一个GPMp，但在有丝分裂细胞中有两个GPMp，这表明普氏耐格里变形虫通过根据细胞周期复制和分离复合物，每个细胞维持一个GPMp。我们的结果证明了存在一种细胞周期依赖性复制复合物，该复合物为下一代基体的从头组装提供了一个位点。
