Interaction between Ran and Mog1 is required for efficient nuclear protein import.
Interaction between Ran and Mog1 is required for efficient nuclear protein import.
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DOI：
10.1074/jbc.m106060200
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发表时间：
2001-11-02
影响因子：
4.8
通讯作者：
Stewart, M
中科院分区：
文献类型：
--
作者：
Baker, RP;Harreman, MT;Stewart, M
Mog1是一种与Ran相互作用的核蛋白，Ran是Ras家族GTPase，赋予核输入和输出途径的方向性。在酿酒酵母（Saccharomyces cerevisiae, Delta MOG1）中缺失MOG1会导致温度敏感生长和核蛋白输入缺陷。Mog1先前已被证明可以刺激Ran的GTP释放，我们在这里证明，在Ran-GTP或Ran- gdp中添加Mog1会导致核苷酸释放，并在Mog1和无核苷酸的Ran之间形成稳定的复合物。此外，MOG1与PRP20 （Ran鸟嘌呤核苷酸交换因子，RanGEF）也结合无核苷酸的Ran，显示出合成致死性。为了探索Mog1-Ran相互作用的功能作用，我们设计了酵母Mog1和Ran的突变体，在体外和体内特异性地破坏它们的相互作用。这些突变表明，相互作用界面涉及酵母Ran中保守的Mog1p残基Asp（62）和Glu（65）以及残基Lys（136）。这些残基的突变降低了Mog1结合和从Ran释放核苷酸的能力。此外，酵母中的E65K-Mog1和K136E-Ran突变导致核输入报告蛋白的温度敏感性和错误定位，与Delta mog1菌株的表型相似。我们的研究结果表明，Mog1的主要功能需要与Ran结合，并且Mog1-Ran相互作用对于体内有效的核蛋白输入是必要的。
Mog1 is a nuclear protein that interacts with Ran, the Ras family GTPase that confers directionality to nuclear import and export pathways. Deletion of MOG1 in Saccharomyces cerevisiae (Delta mog1) causes temperature-sensitive growth and defects in nuclear protein import. Mog1 has previously been shown to stimulate GTP release from Ran and we demonstrate here that addition of Mog1 to either Ran-GTP or Ran-GDP results in nucleotide release and formation of a stable complex between Mog1 and nucleotide-free Ran. Moreover, MOG1 shows synthetic lethality with PRP20, the Ran guanine nucleotide exchange factor (RanGEF) that also binds nucleotide-free Ran. To probe the functional role of the Mog1-Ran interaction, we engineered mutants of yeast Mog1 and Ran that specifically disrupt their interaction both in vitro and in vivo. These mutants indicate that the interaction interface involves conserved Mog1p residues Asp(62) and Glu(65), and residue Lys(136) in yeast Ran. Mutations at these residues decrease the ability of Mog1 to bind and release nucleotide from Ran. Furthermore, the E65K-Mog1 and K136E-Ran mutations in yeast cause temperature sensitivity and mislocalization of a nuclear import reporter protein, similar to the phenotype observed for the Delta mog1 strain. Our results indicate that a primary function of Mog1 requires binding to Ran and that the Mog1-Ran interaction is necessary for efficient nuclear protein import in vivo.