Miranda cargo‐binding domain forms an elongated coiled‐coil homodimer in solution: Implications for asymmetric cell division in Drosophila
Miranda cargo‐binding domain forms an elongated coiled‐coil homodimer in solution: Implications for asymmetric cell division in Drosophila
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DOI：
10.1110/ps.083431408
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发表时间：
2008-05
期刊：
影响因子：
8
通讯作者：
Mohammad S Yousef;H. Kamikubo;M. Kataoka;R. Kato;S. Wakatsuki
中科院分区：
文献类型：
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作者：
Mohammad S Yousef;H. Kamikubo;M. Kataoka;R. Kato;S. Wakatsuki
米兰达是一个多结构域的衔接蛋白，参与果蝇成神经细胞的不对称分裂。米兰达的中心结构域是神经转录因子Prospero、Prospero-mRNA载体Staufen和肿瘤抑制因子Brat的货物结合所必需的。在这里，我们使用小角X射线散射报告了米兰达中心“货物结合”结构域（残基460-660）的第一个溶液结构。散射数据的从头算建模产生了最大线性尺寸（Dmax）为1.22 nm的伸长的“棒状”分子。此外，圆二色性和交联实验表明，货物结合结构域主要是螺旋形的，并在溶液中形成平行卷曲螺旋同源二聚体。基于这些结果，我们将全长米兰达蛋白建模为具有长的中央卷曲螺旋区域的双头双尾同源二聚体。我们讨论了中央结构域的货物结合能力，并提出了一个基于结构的机制，货物释放和及时降解的米兰达在发育成神经细胞。
Miranda is a multidomain adaptor protein involved in neuroblast asymmetric division in Drosophila melanogaster. The central domain of Miranda is necessary for cargo binding of the neural transcription factor Prospero, the Prospero‐mRNA carrier Staufen, and the tumor suppressor Brat. Here, we report the first solution structure of Miranda central “cargo‐binding” domain (residues 460–660) using small‐angle X‐ray scattering. Ab initio modeling of the scattering data yields an elongated “rod‐like” molecule with a maximum linear dimension (Dmax) of ∼22 nm. Moreover, circular dichroism and cross‐linking experiments indicate that the cargo‐binding domain is predominantly helical and forms a parallel coiled‐coil homodimer in solution. Based on the results, we modeled the full‐length Miranda protein as a double‐headed, double‐tailed homodimer with a long central coiled‐coil region. We discuss the cargo‐binding capacity of the central domain and propose a structure‐based mechanism for cargo release and timely degradation of Miranda in developing neuroblasts.