生物谷报道： 氢化酶体是产生ATP和氢的细胞器官，并且在不同的真核生物中发现，如厌氧性鞭毛虫、chytridiomycete真菌、纤毛虫。尽管所有器官都能产生氢，但是这些生物中氢化酶体在结构和代谢上非常不同，就像线粒体亦存在较大差别。这些区别导致生物演化上的大量的争论。这儿我们就生长在蟑螂尾肠的厌氧性纤毛虫Nyctotherus ovalis的氢化酶体，它保持着基本的基因组编码的线粒体的电子传递体。系统发生分析揭示那些需氧性纤毛成蛋白质簇和那些同簇体。详见如下：
Change in the air
Hydrogenosomes are simple organelles found in anaerobic protists and fungi. They are double-membraned and produce ATP and hydrogen, hence suggestions that they are anaerobic derivatives of mitochondria. An alternative view suggests that mitochondria and hydrogenosomes arose from a common ancestor, a facultatively anaerobic bacterium. The discovery of a novel hydrogenosome in Nyctotherus ovalis, a ciliate that lives in the gut of cockroaches, further complicates this debate. It is unique among known hydrogenosomes because, just like a mitochondrion, it retains its own genome. This 'missing link' between hydrogenosomes and mitochondria also has remnants of an electron transport chain characteristic of an aerobic lifestyle.
Nature 434, 74 - 79 (03 March 2005); doi:10.1038/nature03343
An anaerobic mitochondrion that produces hydrogen
BRIGITTE BOXMA1,*, ROB M. DE GRAAF1,*, GEORG W. M. VAN DER STAAY1,*, THEO A. VAN ALEN1, GUENOLA RICARD2, TONI GABALDÓN2, ANGELA H. A. M. VAN HOEK1,†, SEUNG YEO MOON-VAN DER STAAY1, WERNER J. H. KOOPMAN3, JAAP J. VAN HELLEMOND4, ALOYSIUS G. M. TIELENS4, THORSTEN FRIEDRICH5, MARTEN VEENHUIS6, MARTIJN A. HUYNEN2 & JOHANNES H. P. HACKSTEIN1
1 Department of Evolutionary Microbiology, Faculty of Science, Radboud University Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen, The Netherlands
2 Centre for Molecular and Biomolecular Informatics,
3 Microscopical Imaging Centre and Department of Biochemistry, Nijmegen Centre of Molecular Life Sciences (NCMLS), Radboud University Nijmegen Medical Centre, NL-6500 HB Nijmegen, The Netherlands
4 Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, PO Box 80176, NL-3508 TD Utrecht, The Netherlands
5 Albert-Ludwigs-Universität, Institut für Organische Chemie und Biochemie, Albertstrasse 21, D-79104 Freiburg i. Br., Germany
6 Department of Eukaryotic Microbiology, Groningen University, PO Box 14, NL-9750 AA Haren, The Netherlands
* These authors contributed equally to this work
† Present address: RIKILT, Institute of Food Safety, Bornsesteeg 45, NL-6708 PD Wageningen, The Netherlands
Correspondence and requests for materials should be addressed to J.H.P.H. (j.hackstein@science.ru.nl).
Sequences have been deposited at the EMBL database under accession numbers AF480921, AJ871267, AJ871313–AJ871361, AJ871573–AJ871576, AY608627, AY608632–AY608634, AY616150–AY616152, AY619980, AY619981, AY623917, AY623919, AY623925, AY623926, AY628683, AY628684, AY628688.
First Paragraph:
Hydrogenosomes are organelles that produce ATP and hydrogen, and are found in various unrelated eukaryotes, such as anaerobic flagellates, chytridiomycete fungi and ciliates. Although all of these organelles generate hydrogen, the hydrogenosomes from these organisms are structurally and metabolically quite different, just like mitochondria where large differences also exist. These differences have led to a continuing debate about the evolutionary origin of hydrogenosomes. Here we show that the hydrogenosomes of the anaerobic ciliate Nyctotherus ovalis, which thrives in the hindgut of cockroaches, have retained a rudimentary genome encoding components of a mitochondrial electron transport chain. Phylogenetic analyses reveal that those proteins cluster with their homologues from aerobic ciliates. In addition, several nucleus-encoded components of the mitochondrial proteome, such as pyruvate dehydrogenase and complex II, were identified. The N. ovalis hydrogenosome is sensitive to inhibitors of mitochondrial complex I and produces succinate as a major metabolic end product—biochemical traits typical of anaerobic mitochondria. The production of hydrogen, together with the presence of a genome encoding respiratory chain components, and biochemical features characteristic of anaerobic mitochondria, identify the N. ovalis organelle as a missing link between mitochondria and hydrogenosomes.
