Evidence for an early evolutionary emergence of γ-type carbonic anhydrases as components of mitochondrial respiratory complex I
Evidence for an early evolutionary emergence of γ-type carbonic anhydrases as components of mitochondrial respiratory complex I
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DOI：
10.1186/1471-2148-10-176
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发表时间：
2010-06-14
影响因子：
3.4
通讯作者：
Gray, Michael W.
中科院分区：
文献类型：
--
作者：
Gawryluk, Ryan M. R.;Gray, Michael W.
背景：线粒体复合物 I（CI；NADH：泛醌氧化还原酶）的复杂性相对于细菌中的同源复合物显着增加。对动物、真菌和陆地植物/绿藻中 CI 组成的比较分析表明，线粒体 CI 的新成分包括一组所有真核生物共有的 18 种蛋白质和数量可变的谱系特异性亚基。在植物和绿藻中，几种据称与 γ 型碳酸酐酶 (γ CA) 同源的植物特异性蛋白已被鉴定为 CI 的组成部分。然而，人们对单细胞原生生物中 CI 的组成知之甚少，其表征对于我们理解 CI 进化至关重要。结果：我们对阿米巴原生动物卡氏棘阿米巴 CI 进行了串联质谱表征。鉴定出的蛋白质中有两种 γ CA 同源物，AcCa1 和 AccCa2，这表明 γ CA 蛋白并非植物/绿藻所特有。事实上，通过生物信息学搜索，我们在不同的原生生物谱系中检测到了 γ CA 同源物，并且其中一些同源物预计具有 N 末端线粒体靶向肽。 结论：在棘阿米巴（被认为是动物和真菌的近亲，而不是植物）的 CI 中检测到 γ CA 表明，γ CA 蛋白可能是线粒体 CI 的祖先特征，而不是新的植物特异性添加。这一断言得到了多种真核生物核基因组中编码 γ CA 的基因的支持。总之，这些发现强调了 CI 的系统发育广泛特征对于阐明真核生物中 CI 进化的重要性。
Background: The complexity of mitochondrial complex I (CI; NADH: ubiquinone oxidoreductase) has increased considerably relative to the homologous complex in bacteria. Comparative analyses of CI composition in animals, fungi and land plants/green algae suggest that novel components of mitochondrial CI include a set of 18 proteins common to all eukaryotes and a variable number of lineage-specific subunits. In plants and green algae, several purportedly plant-specific proteins homologous to gamma-type carbonic anhydrases (gamma CA) have been identified as components of CI. However, relatively little is known about CI composition in the unicellular protists, the characterizations of which are essential to our understanding of CI evolution.Results: We have performed a tandem mass spectrometric characterization of CI from the amoeboid protozoon Acanthamoeba castellanii. Among the proteins identified were two gamma CA homologs, AcCa1 and AcCa2, demonstrating that gamma CA proteins are not specific to plants/green algae. In fact, through bioinformatics searches we detected gamma CA homologs in diverse protist lineages, and several of these homologs are predicted to possess N-terminal mitochondrial targeting peptides.Conclusions: The detection of gamma CAs in CI of Acanthamoeba, considered to be a closer relative of animals and fungi than plants, suggests that gamma CA proteins may have been an ancestral feature of mitochondrial CI, rather than a novel, plant-specific addition. This assertion is supported by the presence of genes encoding gamma CAs in the nuclear genomes of a wide variety of eukaryotes. Together, these findings emphasize the importance of a phylogenetically broad characterization of CI for elucidating CI evolution in eukaryotes.