Sansom Institute for Health Research, University of South Australia, North Terrace, Adelaide, SA 5000, Australia.
Protist. 2013 Mar;164(2):218-36. doi: 10.1016/j.protis.2012.09.001. Epub 2012 Oct 22.
The dinoflagellates are an important group of eukaryotic, single celled algae. They are the sister group of the Apicomplexa, a group of intracellular parasites and photosynthetic algae including the malaria parasite Plasmodium. Many apicomplexan mitochondria have a number of unusual features, including the lack of a pyruvate dehydrogenase and the existence of a branched TCA cycle. Here, we analyse dinoflagellate EST (expressed sequence tag) data to determine whether these features are apicomplexan-specific, or if they are more widespread. We show that dinoflagellates have replaced a key subunit (E1) of pyruvate dehydrogenase with a subunit of bacterial origin and that transcripts encoding many of the proteins that are essential in a conventional ATP synthase/Complex V are absent, as is the case in Apicomplexa. There is a pathway for synthesis of starch or glycogen as a storage carbohydrate. Transcripts encoding isocitrate lyase and malate synthase are present, consistent with ultrastructural reports of a glyoxysome. Finally, evidence for a conventional haem biosynthesis pathway is found, in contrast to the Apicomplexa, Chromera and early branching dinoflagellates (Perkinsus, Oxyrrhis).
甲藻是一类重要的真核单细胞藻类，是顶复门的姐妹群。顶复门是一类内寄生的生物，包括疟原虫等光合生物。许多顶复门的线粒体具有一些不寻常的特征，包括缺乏丙酮酸脱氢酶和存在分支三羧酸循环。在这里，我们分析了甲藻的 EST（表达序列标签）数据，以确定这些特征是顶复门特有的，还是更为普遍存在的。我们发现甲藻已经用细菌来源的亚基替代了丙酮酸脱氢酶的一个关键亚基，并且编码许多在传统的 ATP 合酶/复合物 V 中必不可少的蛋白的转录本缺失，这与顶复门的情况相同。存在合成淀粉或糖原作为储存碳水化合物的途径。存在异柠檬酸裂解酶和苹果酸合酶的转录本，与过氧化物酶体的超微结构报告一致。最后，与顶复门、Chromera 和早期分支甲藻（ Perkinsus 、 Oxyrrhis ）相反，发现了一个传统的血红素生物合成途径的证据。
