Embley T Martin, van der Giezen Mark, Horner David S, Dyal Patricia L, Bell Samantha, Foster Peter G
Department of Zoology, The Natural History Museum, London, SW7 5BD, UK.
IUBMB Life. 2003 Jul;55(7):387-95. doi: 10.1080/15216540310001592834.
Available data suggest that unusual organelles called hydrogenosomes, that make ATP and hydrogen, and which are found in diverse anaerobic eukaryotes, were once mitochondria. The evolutionary origins of the enzymes used to make hydrogen, pyruvate:ferredoxin oxidoreductase (PFO) and hydrogenase, are unresolved, but it seems likely that both were present at an early stage of eukaryotic evolution. Once thought to be restricted to a few unusual anaerobes, these proteins are found in diverse eukaryotic cells, including our own, where they are targeted to different cell compartments. Organelles related to mitochondria and hydrogenosomes have now been found in species of anaerobic and parasitic protozoa that were previously thought to have separated from other eukaryotes before the mitochondrial endosymbiosis. Thus it is possible that all eukaryotes may eventually be shown to contain an organelle of mitochondrial ancestry, bearing testimony to the important role that the mitochondrial endosymbiosis has played in eukaryotic evolution. It remains to be seen if members of this family of organelles share a common function essential to the eukaryotic cell, that provides the underlying selection pressure for organelle retention under different living conditions.
现有数据表明，一种名为氢化酶体的特殊细胞器曾是线粒体，这种细胞器能产生三磷酸腺苷（ATP）和氢气，存在于多种厌氧真核生物中。用于产生氢气的酶，即丙酮酸：铁氧化还原蛋白氧化还原酶（PFO）和氢化酶的进化起源尚未明确，但它们似乎在真核生物进化的早期阶段就已存在。这些蛋白质曾被认为仅存在于少数特殊的厌氧菌中，如今在包括人类细胞在内的多种真核细胞中都有发现，且在不同细胞区室中发挥作用。现已在一些厌氧和寄生原生动物物种中发现了与线粒体和氢化酶体相关的细胞器，这些物种此前被认为在线粒体共生之前就已与其他真核生物分离。因此，有可能最终证明所有真核生物都含有具有线粒体祖先特征的细胞器，这证明了线粒体共生在真核生物进化中所起的重要作用。这些细胞器家族的成员是否共享对真核细胞至关重要的共同功能，从而为在不同生活条件下保留细胞器提供潜在的选择压力，仍有待观察。
