Identification of a Gene for Pyruvate-Insensitive Mitochondrial Alternative Oxidase Expressed in the Thermogenic Appendices in Arum maculatum
Identification of a Gene for Pyruvate-Insensitive Mitochondrial Alternative Oxidase Expressed in the Thermogenic Appendices in Arum maculatum
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DOI：
10.1104/pp.111.186932
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发表时间：
2011-12-01
期刊：
影响因子：
7.4
通讯作者：
Moore, Anthony L.
中科院分区：
文献类型：
--
作者：
Ito, Kikukatsu;Ogata, Takafumi;Moore, Anthony L.
产热植物的产热归因于交替氧化酶（AOX）表达的大量增加。AOX作为线粒体呼吸链中的替代末端氧化酶，在那里它将分子氧还原为水。与线粒体末端氧化酶、细胞色素c氧化酶相反，AOX是非质子动力的，因此允许泛醇和氧之间的自由能急剧下降以热的形式耗散。利用逆转录-聚合酶链反应为基础的克隆，我们发现，虽然至少有七个AOX的cDNA存在（AmAOX 1a，-1b，-1c，-1d，-1e，-1f，和-1g）在斑叶天南星，每个器官和发育调控是不同的。特别是，AmAOX 1 e转录物的表达似乎占主导地位的产热附录中的七个AmAOXs。有趣的是，AmAOX 1 e的氨基酸序列表明，在几乎所有其他AOX序列中发现的ENV元件，包括AmAOX 1a，-1b，-1c，-1d和-1f，被QNT取代。通过纳米液相色谱-串联质谱分析产热性阑尾线粒体蛋白，证实AmAOX 1 e中存在QNT基序。利用酵母异源表达系统制备的线粒体的进一步功能分析表明，AmAOX 1 e对丙酮酸的刺激不敏感。这些数据表明，一个QNT类型的对谷氨酸盐不敏感的AOX，AmAOX 1 e，在A.斑点。
Heat production in thermogenic plants has been attributed to a large increase in the expression of the alternative oxidase (AOX). AOX acts as an alternative terminal oxidase in the mitochondrial respiratory chain, where it reduces molecular oxygen to water. In contrast to the mitochondrial terminal oxidase, cytochrome c oxidase, AOX is nonprotonmotive and thus allows the dramatic drop in free energy between ubiquinol and oxygen to be dissipated as heat. Using reverse transcription-polymerase chain reaction-based cloning, we reveal that, although at least seven cDNAs for AOX exist (AmAOX1a, -1b, -1c, -1d, -1e, -1f, and -1g) in Arum maculatum, the organ and developmental regulation for each is distinct. In particular, the expression of AmAOX1e transcripts appears to predominate in thermogenic appendices among the seven AmAOXs. Interestingly, the amino acid sequence of AmAOX1e indicates that the ENV element found in almost all other AOX sequences, including AmAOX1a, -1b, -1c, -1d, and -1f, is substituted by QNT. The existence of a QNT motif in AmAOX1e was confirmed by nano-liquid chromatography-tandem mass spectrometry analysis of mitochondrial proteins from thermogenic appendices. Further functional analyses with mitochondria prepared using a yeast heterologous expression system demonstrated that AmAOX1e is insensitive to stimulation by pyruvate. These data suggest that a QNT type of pyruvate-insensitive AOX, AmAOX1e, plays a crucial role in stage- and organ-specific heat production in the appendices of A. maculatum.