Arabidopsis GCP3-INTERACTING PROTEIN1/MOZAET1 is an integral component of the Y-tubulin-containing microtubule nucleating complex
Arabidopsis GCP3-INTERACTING PROTEIN1/MOZAET1 is an integral component of the Y-tubulin-containing microtubule nucleating complex
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拟南芥 GCP3 相互作用蛋白 1/MOZAET1 是含 Y 微管蛋白的微管成核复合物的组成部分
DOI：
10.1111/j.1365-313x.2012.04988.x
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Hashimoto T
中科院分区：
文献类型：
--
作者：
Nakamura M;Yagi N;Kato T;Fujita S;Kawashima N;Ehrhardt DW;Hashimoto T
真核细胞中的微管由含有γ-微管蛋白和一个同源γ-微管蛋白复合物蛋白（GCPs）家族的环形复合物成核，但复合物的亚基组成在真菌、动物和植物中可能不同。拟南芥GCP 3相互作用蛋白1（GIP 1）是一种与GCP家族没有同源性的小蛋白，在体外与GCP 3相互作用，是脊椎动物有丝分裂纺锤体组织蛋白的植物同源物，与γ微管蛋白1（MOZART 1）环相关，MOZART 1是最近在人类细胞系中鉴定的γ微管蛋白复合物的组分。 在这项研究中，我们确定了两个密切相关的拟南芥GIP 1 s：GIP 1a和GIP 1b。gip 1a和gip 1b的单突变体与野生型植物无法区分，但其双突变体具有胚胎致死性，并显示出雄配子体发育受损。使用GIP 1a与绿色荧光蛋白（GFP）的功能性融合物从拟南芥植物中纯化含有GIP 1a的复合物，其含有先前在拟南芥γ微管蛋白复合物中鉴定的所有亚基（除NEDD 1外）。GIP 1a和GIP 1b在酵母中与拟南芥GCP 3特异性相互作用。GFP-GIP 1a标记的有丝分裂微管阵列的模式与含有GCP 2或GCP 3的γ-微管蛋白复合物在植物中的定位基本一致，但部分不同。 在间期皮质阵列中，标记的复合物优先被招募到现有的微管，新的微管有效地成核。然而，与标记GCP 2或GCP 3的复合物相反，很少观察到它们在没有微管的皮质区的募集。这些结果表明，GIP 1/MOZART 1是拟南芥γ-微管蛋白复合物的一个子集的组成部分。
Microtubules in eukaryotic cells are nucleated from ring‐shaped complexes that contain γ‐tubulin and a family of homologous γ‐tubulin complex proteins (GCPs), but the subunit composition of the complexes can vary among fungi, animals and plants. Arabidopsis GCP3‐interacting protein 1 (GIP1), a small protein with no homology to the GCP family, interacts with GCP3in vitro, and is a plant homolog of vertebrate mitotic‐spindle organizing protein associated with a ring of γ‐tubulin 1 (MOZART1), a recently identified component of the γ‐tubulin complex in human cell lines. In this study, we characterized two closely related Arabidopsis GIP1s: GIP1a and GIP1b. Single mutants ofgip1aandgip1bwere indistinguishable from wild‐type plants, but their double mutant was embryonic lethal, and showed impaired development of male gametophytes. Functional fusions of GIP1a with green fluorescent protein (GFP) were used to purify GIP1a‐containing complexes from Arabidopsis plants, which contained all the subunits (except NEDD1) previously identified in the Arabidopsis γ‐tubulin complexes. GIP1a and GIP1b interacted specifically with Arabidopsis GCP3 in yeast. GFP‐GIP1a labeled mitotic microtubule arrays in a pattern largely consistent with, but partly distinct from, the localization of the γ‐tubulin complex containing GCP2 or GCP3in planta. In interphase cortical arrays, the labeled complexes were preferentially recruited to existing microtubules, from which new microtubules were efficiently nucleated. However, in contrast to complexes labeled with tagged GCP2 or GCP3, their recruitment to cortical areas with no microtubules was rarely observed. These results indicate that GIP1/MOZART1 is an integral component of a subset of the Arabidopsis γ‐tubulin complexes.