Arabidopsis Rho-related GTPases: Differential gene expression in pollen and polar localization in fission yeast
Arabidopsis Rho-related GTPases: Differential gene expression in pollen and polar localization in fission yeast
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DOI：
10.1104/pp.118.2.407
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发表时间：
1998-10-01
期刊：
影响因子：
7.4
通讯作者：
Yang, ZB
中科院分区：
文献类型：
--
作者：
Li, H;Wu, G;Yang, ZB
Rho小分子CTP结合蛋白是真核细胞信号转导中功能广泛、保守的分子开关。植物含有一个独特的Rho-GTP酶亚家族，称为POP(植物中的Rho相关GTP酶)。我们之前关于抗体注射的研究表明，豌豆Rop GTP酶Rop1Ps对花粉管的生长至关重要。在本研究中，我们发现Rop1Ps的拟南芥同源基因Rop1At的过表达诱导分裂酵母(Schizosaccharmyces Pombe)各向同性的细胞生长，绿色荧光蛋白标记的Rop1At在酵母中的生长位置显示出极性定位。我们发现Rop1At和另外两个拟南芥Pop，Rop3At和Rop5At都在成熟花粉中表达。这三种花粉POPs都与Rop1Ps属于同一个亚群，并与那些在成熟花粉中不表达的Rop有所不同，这表明Pop GTP酶的结构保守性与它们在花粉中的基因表达是耦合的。然而，Rop1At的花粉特异转录物积累量远高于Rop3At和Rop5At。此外，Rop1At在花药中特异表达，而Rop3At和Rop5At也在营养组织中表达。在含有Rop1At启动子：GUS融合基因的转基因植株中，GUS在成熟花粉和花粉管中特异表达。我们认为Rop1At可能在花粉极化细胞生长的调节中起主导作用，而其近亲Rop3At和Rop5At可能在功能上与花粉中的Rop1At冗余。
The Rho small CTP-binding proteins are versatile, conserved molecular switches in eukaryotic signal transduction. Plants contain a unique subfamily of Rho-GTPases called Pop (Rho-related GTPases from plants). Our previous studies involving injection of antibodies indicated that the pea Rop GTPase Rop1Ps is critical for pollen tube growth. In this study we show that overexpression of an apparent Arabidopsis ortholog of Rop1Ps, Rop1At, induces isotropic cell growth in fission yeast (Schizosaccharomyces pombe) and that green fluorescence protein-tagged Rop1At displays polar localization to the site of growth in yeast. We found that Rop1At and two other Arabidopsis Pops, Rop3At and Rop5At, are all expressed in mature pollen. All three pollen Pops fall into the same subgroup as Rop1Ps and diverge from those Rops that are not expressed in mature pollen, suggesting a coupling of the structural conservation of Pop GTPases to their gene expression in pollen. However, pollen-specific transcript accumulation for Rop1At is much higher than that for Rop3At and Rop5At. Furthermore, Rop1At is specifically expressed in anthers, whereas Rop3At and Rop5At are also expressed in vegetative tissues. In transgenic plants containing the Rop1At promoter:GUS fusion gene, GUS is specifically expressed in mature pollen and pollen tubes. We propose that Rop1At may play a predominant role in the regulation of polarized cell growth in pollen, whereas its close relatives Rop3At and Rop5At may be functionally redundant to Rop1At in pollen.