Department of Biology, Wilfrid Laurier University, 75 University Ave. W., Waterloo, Ontario, N2L 3C5, Canada.
Gene. 2013 Sep 10;526(2):275-86. doi: 10.1016/j.gene.2013.04.072. Epub 2013 May 9.
Alternative oxidase (AOX) is a terminal ubiquinol oxidase present in the respiratory chain of all angiosperms investigated to date, but AOX distribution in other members of the Viridiplantae is less clear. We assessed the taxonomic distribution of AOX using bioinformatics. Multiple sequence alignments compared AOX proteins and examined amino acid residues involved in AOX catalytic function and post-translational regulation. Novel AOX sequences were found in both Chlorophytes and Streptophytes and we conclude that AOX is widespread in the Viridiplantae. AOX multigene families are common in non-angiosperm plants and the appearance of AOX1 and AOX2 subtypes pre-dates the divergence of the Coniferophyta and Magnoliophyta. Residues involved in AOX catalytic function are highly conserved between Chlorophytes and Streptophytes, while AOX post-translational regulation likely differs in these two lineages. We demonstrate experimentally that an AOX gene is present in the moss Physcomitrella patens and that the gene is transcribed. Our findings suggest that AOX will likely exert an influence on plant respiration and carbon metabolism in non-angiosperms such as green algae, bryophytes, liverworts, lycopods, ferns, gnetophytes, and gymnosperms and that further research in these systems is required.
交替氧化酶（AOX）是一种存在于迄今为止所有被子植物呼吸链中的末端泛醌氧化酶，但 AOX 在其他绿藻门成员中的分布情况尚不清楚。我们使用生物信息学评估了 AOX 的分类分布。多重序列比对比较了 AOX 蛋白，并研究了参与 AOX 催化功能和翻译后调控的氨基酸残基。在绿藻门和轮藻门中都发现了新的 AOX 序列，因此我们得出结论，AOX 在绿藻门中广泛存在。AOX 多基因家族在非被子植物中很常见，而 AOX1 和 AOX2 亚型的出现早于松柏纲和木兰纲的分化。绿藻门和轮藻门之间 AOX 催化功能相关的残基高度保守，而这两个谱系的 AOX 翻译后调控可能不同。我们通过实验证明，苔藓植物Physcomitrella patens 中存在 AOX 基因，并且该基因被转录。我们的研究结果表明，AOX 可能会对非被子植物（如绿藻、苔藓植物、地钱植物、石松植物、蕨类植物、买麻藤植物和裸子植物）的植物呼吸和碳代谢产生影响，需要在这些系统中进一步研究。
