The Rsr1/Bud1 GTPase interacts with itself and the Cdc42 GTPase during bud-site selection and polarity establishment in budding yeast.
The Rsr1/Bud1 GTPase interacts with itself and the Cdc42 GTPase during bud-site selection and polarity establishment in budding yeast.
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DOI：
10.1091/mbc.e10-03-0232
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发表时间：
2010-09-01
影响因子：
3.3
通讯作者：
Park HO
中科院分区：
文献类型：
--
作者：
Kang PJ;Béven L;Hariharan S;Park HO
双分子荧光互补测定允许在体内的同型和异型GT3相互作用的可视化。Rsr 1的同型相互作用涉及其多碱基区域，并依赖于其GDP-GTP交换因子。GTP酶的二聚化可能是建立细胞不对称性的有效机制。细胞极化沿着单个轴发生，该轴通常响应于空间线索而确定。在芽殖酵母中，Rsr 1 GTbind及其调节因子在响应细胞类型特异性线索的适当皮层位置指导细胞极性的建立。在这里，我们使用体内和体外方法的组合来了解Rsr 1极化是如何建立的。我们发现，Rsr 1协会与自己在空间和时间控制的方式。Rsr 1的同型相互作用和定位到母芽颈和随后的分裂位点依赖于其GDP-GTP交换因子Bud 5。对Rsr 1突变体的分析表明，Bud 5将Rsr 1募集到这些位点并促进同源二聚体的形成。Rsr 1在体内也表现出与Cdc 42 GT3的异型相互作用。我们发现，Rsr 1的多碱基区域是必要的有效的同型和异型相互作用，选择一个合适的生长位点，和极性的建立。因此，我们的研究结果表明，二聚体的GTP酶可能是一个有效的机制，建立细胞的不对称性。
Bimolecular fluorescence complementation assays allow the visualization of the homotypic and heterotypic GTPase interactions in vivo. The Rsr1 homotypic interaction involves its polybasic region and depends on its GDP-GTP exchange factor. Dimerization of GTPases may be an efficient mechanism to set up cellular asymmetry. Cell polarization occurs along a single axis that is generally determined in response to spatial cues. In budding yeast, the Rsr1 GTPase and its regulators direct the establishment of cell polarity at the proper cortical location in response to cell type–specific cues. Here we use a combination of in vivo and in vitro approaches to understand how Rsr1 polarization is established. We find that Rsr1 associates with itself in a spatially and temporally controlled manner. The homotypic interaction and localization of Rsr1 to the mother-bud neck and to the subsequent division site are dependent on its GDP-GTP exchange factor Bud5. Analyses of rsr1 mutants suggest that Bud5 recruits Rsr1 to these sites and promotes the homodimer formation. Rsr1 also exhibits heterotypic interaction with the Cdc42 GTPase in vivo. We show that the polybasic region of Rsr1 is necessary for the efficient homotypic and heterotypic interactions, selection of a proper growth site, and polarity establishment. Our findings thus suggest that dimerization of GTPases may be an efficient mechanism to set up cellular asymmetry.