Functional specialisation of yeast Rho1 GTP exchange factors
Functional specialisation of yeast Rho1 GTP exchange factors
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DOI：
10.1242/jcs.100685
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发表时间：
2012-06-01
影响因子：
4
通讯作者：
Gray, Joseph V.
中科院分区：
文献类型：
--
作者：
Krause, Sue Ann;Cundell, Michael J.;Gray, Joseph V.
Rho GTP酶以复杂的时空模式进行调控，这可能至少部分取决于其GTP交换因子(GEF)的多样性。在这里，我们研究了Rom2和Tus1 GEF激活酵母Rho1 GTP酶(哺乳动物RhoA的同源基因)的功能专门化的程度和基础。首先，我们发现这些GEF选择性地激活不同的Rho1效应器分支。其次，围绕ROM2和TUS1的人工遗传网络证实了这些GEF在全球的活体作用非常不同。第三，GEF在功能上不可互换：Tus1不能取代Rom2的基本作用，即使过度表达也是如此。第四，我们发现Rom2和Tus1的定位不同：Rom2位于生长的芽面，胞质分裂时位于芽颈；Tus1仅位于芽颈，但有明显的模式。最后，我们发现这些GEF依赖于不同的蛋白质辅助因子：Rom2的功能和定位在很大程度上取决于AcK1，一个含有SEL1结构域的蛋白质；Tus1的功能和定位在很大程度上取决于Tus1相互作用的蛋白质Ypl066w(我们称之为Rgl1)。我们已经揭示了Rho1 GEF之间令人惊讶的多样性水平，这为Rho1的时空控制贡献了另一个水平的复杂性。
Rho GTPases are regulated in complex spatiotemporal patterns that might be dependent, in part at least, on the multiplicity of their GTP exchange factors (GEFs). Here, we examine the extent of and basis for functional specialisation of the Rom2 and Tus1 GEFs that activate the yeast Rho1 GTPase, the orthologue of mammalian RhoA. First, we find that these GEFs selectively activate different Rho1-effector branches. Second, the synthetic genetic networks around ROM2 and TUS1 confirm very different global in vivo roles for these GEFs. Third, the GEFs are not functionally interchangeable: Tus1 cannot replace the essential role of Rom2, even when overexpressed. Fourth, we find that Rom2 and Tus1 localise differently: Rom2 to the growing bud surface and to the bud neck at cytokinesis; Tus1 only to the bud neck, but in a distinct pattern. Finally, we find that these GEFs are dependent on different protein co-factors: Rom2 function and localisation is largely dependent on Ack1, a SEL1-domain-containing protein; Tus1 function and localisation is largely dependent on the Tus1-interacting protein Ypl066w (which we name Rgl1). We have revealed a surprising level of diversity among the Rho1 GEFs that contributes another level of complexity to the spatiotemporal control of Rho1.