Alternative oxidase in animals: unique characteristics and taxonomic distribution
Alternative oxidase in animals: unique characteristics and taxonomic distribution
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DOI：
10.1242/jeb.032151
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发表时间：
2009-08-15
影响因子：
2.8
通讯作者：
Staples, James F.
中科院分区：
文献类型：
--
作者：
McDonald, Allison E.;Vanlerberghe, Greg C.;Staples, James F.
替代氧化酶(AOX)是一种泛喹酚氧化酶，它在呼吸电子传递链中引入一个分支点，绕过复合体III和IV，导致抗氰化物呼吸。以前，AOX被认为仅限于植物、一些真菌和原生动物，但最近的研究表明，AOX存在于包括动物在内的大多数生物界。在目前的研究中，我们在代表9个门的28种动物中鉴定了AOX。这扩大了已知的AOX在动物中的分类分布，增加了10个物种和两个门。利用生物信息学的方法，我们在动物门Porifera、Placo zoa、Cnidaria、软体动物、环节动物、线虫、棘皮动物、半角动物和脊索动物中发现了AOX基因序列。利用逆转录聚合酶链式反应(RT-PCR)设计的简并引物识别动物AOX的保守区，证明了AOX基因在不同门的几种动物中都有转录。对AOX全长序列的分析显示，在该蛋白的C-末端区域有一个动物AOX所独有的氨基酸基序。动物AOX也缺乏一个N-末端的半胱氨酸残基，这是已知的对植物AOX酶调节很重要的残基。我们得出结论，AOX的存在是动物的祖先状态，并假设它在包括脊椎动物在内的某些谱系中的缺失是由于基因丢失事件造成的。
Alternative oxidase (AOX), a ubiquinol oxidase, introduces a branch point into the respiratory electron transport chain, bypassing complexes III and IV and resulting in cyanide-resistant respiration. Previously, AOX was thought to be limited to plants and some fungi and protists but recent work has demonstrated the presence of AOX in most kingdoms of life, including animals. In the present study we identified AOX in 28 animal species representing nine phyla. This expands the known taxonomic distribution of AOX in animals by 10 species and two phyla. Using bioinformatics we found AOX gene sequences in members of the animal phyla Porifera, Placozoa, Cnidaria, Mollusca, Annelida, Nematoda, Echinodermata, Hemichordata and Chordata. Using reverse-transcriptase polymerase chain reaction (RT-PCR) with degenerate primers designed to recognize conserved regions of animal AOX, we demonstrated that AOX genes are transcribed in several animals from different phyla. An analysis of full-length AOX sequences revealed an amino acid motif in the C-terminal region of the protein that is unique to animal AOXs. Animal AOX also lacks an N-terminal cysteine residue that is known to be important for AOX enzyme regulation in plants. We conclude that the presence of AOX is the ancestral state in animals and hypothesize that its absence in some lineages, including vertebrates, is due to gene loss events.