Degradation of mitochondrial alternative oxidase in the appendices of Arum maculatum.
Degradation of mitochondrial alternative oxidase in the appendices of Arum maculatum.
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DOI：
10.1042/bcj20200515
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发表时间：
2020-09-18
期刊：
影响因子：
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通讯作者：
Moore AL
中科院分区：
文献类型：
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作者：
Ito K;Ogata T;Seito T;Umekawa Y;Kakizaki Y;Osada H;Moore AL
抗氰交替氧化酶（Cyanide-resistant alternative oxidase，AOX）是一种位于线粒体内膜的核编码的醌醇氧化酶。虽然AOX蛋白质的质量控制预计在线粒体呼吸升高中发挥作用，但尚不清楚产热植物是否具有AOX线粒体降解的分子机制。为了更好地理解线粒体中AOX周转的机制，我们使用来自斑叶天南星（Arum maculatum）附件不同阶段的线粒体进行了一系列的细胞器内AOX降解测定。我们的分析清楚地表明，阑尾中某些阶段的AOX蛋白在30°C下降解，这接近产热过程中观察到的最高阑尾温度。有趣的是，这种温度依赖性蛋白酶活性被半胱氨酸蛋白酶抑制剂E-64特异性抑制。此外，E-64-敏感和DCG-04-标记的活性线粒体蛋白酶的纯化和随后的纳米LC-MS/MS分析揭示了一种约30 kDa的蛋白质，其具有与来自Phoenix dactylifera的半胱氨酸蛋白酶1-样蛋白质相同的部分肽序列。 我们的数据共同表明AOX是A.斑点。一个可能的逆行信号级联介导的特异性降解AOX蛋白及其生理意义进行了讨论。
Cyanide-resistant alternative oxidase (AOX) is a nuclear-encoded quinol oxidase located in the inner mitochondrial membrane. Although the quality control of AOX proteins is expected to have a role in elevated respiration in mitochondria, it remains unclear whether thermogenic plants possess molecular mechanisms for the mitochondrial degradation of AOX. To better understand the mechanism of AOX turnover in mitochondria, we performed a series of in organello AOX degradation assays using mitochondria from various stages of the appendices of Arum maculatum. Our analyses clearly indicated that AOX proteins at certain stages in the appendices are degraded at 30°C, which is close to the maximum appendix temperature observed during thermogenesis. Interestingly, such temperature-dependent protease activities were specifically inhibited by E-64, a cysteine protease inhibitor. Moreover, purification and subsequent nano LC–MS/MS analyses of E-64-sensitive and DCG-04-labeled active mitochondrial protease revealed an ∼30 kDa protein with an identical partial peptide sequence to the cysteine protease 1-like protein from Phoenix dactylifera. Our data collectively suggest that AOX is a potential target for temperature-dependent E-64-sensitive cysteine protease in the appendices of A. maculatum. A possible retrograde signalling cascade mediated by specific degradation of AOX proteins and its physiological significance are discussed.