Saccharomyces cerevisiae Rbg1 Protein and Its Binding Partner Gir2 Interact on Polyribosomes with Gcn1
Saccharomyces cerevisiae Rbg1 Protein and Its Binding Partner Gir2 Interact on Polyribosomes with Gcn1
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DOI：
10.1128/ec.00356-08
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发表时间：
2009-07-01
期刊：
影响因子：
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通讯作者：
Maddock, J. R.
中科院分区：
文献类型：
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作者：
Wout, P. K.;Sattlegger, E.;Maddock, J. R.
Rbg1 是一种以前未表征的酿酒酵母蛋白，属于 GTP 结合蛋白的 Obg/CgtA 亚家族，其成员参与原核生物和真核生物的核糖体功能。我们在此表明 Rbg1 与核糖体翻译特别相关。此外，在本研究中，通过酵母双杂交筛选鉴定出与 Rbg1 相互作用的蛋白质，包括 Tma46、Ygr250c、Yap1 和 Gir2。 Gir2 包含与 Gcn2 相似的 GI（Gcn2 和 Impact）结构域，是克服氨基酸短缺所需的一般氨基酸控制途径的重要因素。有趣的是，我们发现 Gir2 与 Gcn2 一样，通过其 GI 结构域与 Gcn1 相互作用，并且在模拟氨基酸饥饿的条件下，Gir2 的过度表达会导致生长抑制，而这种抑制可以通过 Gcn2 共过度表达来逆转。此外，我们发现 Gir2 也与多核糖体共分级，并且这种分级模式部分依赖于 Gcn1 的存在。基于这些发现，我们得出结论，Rbg1 及其相互作用伙伴 Gir2 与核糖体相关，并讨论了它们可能的生物学作用。
Rbg1 is a previously uncharacterized protein of Saccharomyces cerevisiae belonging to the Obg/CgtA subfamily of GTP-binding proteins whose members are involved in ribosome function in both prokaryotes and eukaryotes. We show here that Rbg1 specifically associates with translating ribosomes. In addition, in this study proteins were identified that interact with Rbg1 by yeast two-hybrid screening and include Tma46, Ygr250c, Yap1, and Gir2. Gir2 contains a GI (Gcn2 and Impact) domain similar to that of Gcn2, an essential factor of the general amino acid control pathway required for overcoming amino acid shortage. Interestingly, we found that Gir2, like Gcn2, interacts with Gcn1 through its GI domain, and overexpression of Gir2, under conditions mimicking amino acid starvation, resulted in inhibition of growth that could be reversed by Gcn2 co-overexpression. Moreover, we found that Gir2 also cofractionated with polyribosomes, and this fractionation pattern was partially dependent on the presence of Gcn1. Based on these findings, we conclude that Rbg1 and its interacting partner Gir2 associate with ribosomes, and their possible biological roles are discussed.