Data from: Organelles that illuminate the origins of Trichomonas hydrogenosomes and Giardia mitosomes

Many anaerobic microbial parasites possess highly modified mitochondria
known as mitochondrion-related organelles (MROs). The best-studied of
these are the hydrogenosomes of Trichomonas vaginalis and Spironucleus
salmonicida, which produce ATP anaerobically through substrate-level
phosphorylation with concomitant hydrogen production; and the mitosomes of
Giardia intestinalis, which are functionally reduced and lack any role in
ATP production. However, to understand the metabolic specializations that
these MROs underwent in adaptation to parasitism, data from their
free-living relatives are needed. Here, we present a large-scale
comparative transcriptomic study of MROs across a major eukaryotic group,
Metamonada, examining lineage-specific gain and loss of metabolic
functions in the MROs of Trichomonas, Giardia, Spironucleus and their
free-living relatives. Our analyses uncover a complex history of ATP
production machinery in diplomonads such as Giardia, and their closest
relative, Dysnectes; and a correlation between the glycine cleavage
machinery and lifestyles. Our data further suggest the existence of a
previously undescribed biochemical class of MRO that generates hydrogen
but is incapable of ATP synthesis.

许多厌氧微生物寄生虫拥有高度特化改造的线粒体，这类细胞器被称为线粒体相关细胞器（mitochondrion-related organelles，MROs）。其中研究最为深入的两类是阴道毛滴虫（Trichomonas vaginalis）与鲑鱼旋滴虫（Spironucleus salmonicida）的氢化酶体（hydrogenosomes）——这类细胞器可通过底物水平磷酸化进行厌氧ATP合成，并伴随氢气产生；以及蓝氏贾第鞭毛虫（Giardia intestinalis）的纺锤剩体（mitosomes），后者功能简化，完全不参与ATP合成。然而，要阐明这些MROs在适应寄生生活过程中演化出的代谢特化机制，需获取其自由生活近亲的相关研究数据。本研究针对真核生物大类群后滴门（Metamonada）内的MROs开展了大规模比较转录组学分析，系统考察了阴道毛滴虫、蓝氏贾第鞭毛虫、鲑鱼旋滴虫及其自由生活近亲的MROs代谢功能的谱系特异性得失情况。研究结果揭示了双滴虫目（diplomonads，如蓝氏贾第鞭毛虫）及其近缘类群Dysnectes属物种的ATP合成装置演化历史的复杂性，同时发现甘氨酸裂解系统与物种生活方式之间存在显著相关性。此外，本研究数据还提示存在一类此前未被报道的、可产氢但无法合成ATP的MROs生化亚型。