Mitochondrial AAA-ATPase Msp1 detects mislocalized tail-anchored proteins through a dual-recognition mechanism
Mitochondrial AAA-ATPase Msp1 detects mislocalized tail-anchored proteins through a dual-recognition mechanism
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线粒体 AAA-ATPase Msp1 通过双重识别机制检测错误定位的尾部锚定蛋白
DOI：
10.15252/embr.201846989
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发表时间：
2019-04-01
期刊：
影响因子：
7.7
通讯作者：
Jiang, Hui
中科院分区：
文献类型：
--
作者：
Li, Lanlan;Zheng, Jing;Jiang, Hui
保守的AAA-ATP酶Msp 1嵌入在线粒体外膜中，并在引导进入尾锚定（GET）途径功能障碍时去除错误定位的尾锚定（TA）蛋白。目前尚不清楚Msp 1如何识别其底物。在这里，我们广泛表征Msp 1及其底物，包括脑靶向的Pex 15 Delta 30和全长Pex 15，其在Pex 19功能障碍时错误定位于线粒体，但不是GET途径。此外，我们确定了两个新的底物，Frt 1和Ysy 6。我们的研究结果表明，错误定位的TA蛋白暴露在细胞质中的疏水表面，并通过保守的疏水残基Msp 1识别。将疏水补丁引入线粒体TA蛋白将其转化为Msp 1底物。此外，Pex 15 Delta 30和Frt 1含有对它们的线粒体错误定位至关重要的碱性膜间空间（IMS）残基。值得注意的是，Msp 1通过其IMS结构域中的酸性D12残基识别这一特征。这种双重识别机制涉及Msp 1和底物的胞质和IMS结构域的相互作用，极大地促进了底物识别，并且是Msp 1保护线粒体功能所需的。
The conserved AAA-ATPase Msp1 is embedded in the outer mitochondrial membrane and removes mislocalized tail-anchored (TA) proteins upon dysfunction of the guided entry of tail-anchored (GET) pathway. It remains unclear how Msp1 recognizes its substrates. Here, we extensively characterize Msp1 and its substrates, including the mitochondrially targeted Pex15 Delta 30, and full-length Pex15, which mislocalizes to mitochondria upon dysfunction of Pex19 but not the GET pathway. Moreover, we identify two new substrates, Frt1 and Ysy6. Our results suggest that mislocalized TA proteins expose hydrophobic surfaces in the cytoplasm and are recognized by Msp1 through conserved hydrophobic residues. Introducing a hydrophobic patch into mitochondrial TA proteins transforms them into Msp1 substrates. In addition, Pex15 Delta 30 and Frt1 contain basic inter-membrane space (IMS) residues critical for their mitochondrial mistargeting. Remarkably, Msp1 recognizes this feature through the acidic D12 residue in its IMS domain. This dual-recognition mechanism involving interactions at the cytoplasmic and IMS domains of Msp1 and substrates greatly facilitates substrate recognition and is required by Msp1 to safeguard mitochondrial functions.