Isolation, characterization and localization of ATP synthases of the archaeal genera Ignicoccus and Nanoarchaeum
Zusammenfassung der Projektergebnisse
The Crenarchaeon Ignicoccus hospitalis is an anaerobic, obligate chemolithoautotrophic hyperthermophile, growing by reduction of elemental sulfur using molecular hydrogen as electron donor. Together with Nanoarchaeum equitans it forms a unique, archaeal biocoenosis, in which I. hospitalis serves as host for N. equitans. This strong dependence is affirmed by the fact that N. equitans obtains its lipids and amino acids from the host. I. hospitalis cells exhibit several unique features: they use a novel CO2 fixation pathway, the dicarboxylate/4-hydroxybutyrate pathway; and they exhibit a unique cell envelope for Archaea consisting of two membranes. These membranes form two cell compartments, a tightly packed cytoplasm surrounded by a weakly staining intermembrane compartment (IMC) with a width up to 1000 nm. In this project the ATP synthase of I. hospitalis was successfully purified. The catalytic active A1 subcomplex (440-kDa complex) consists of the subunits A3B3EF, while the membrane-bound Ao subcomplex contains the subunits a, c, C, D, and H. Therefore, this ATP synthase represents a typical archaeal ATP synthase of the A1Ao type. Antibodies against this enzyme were generated and used for immuno-TEM analyses of ultrathin sections and immunofluorescence experiments. It could be demonstrated that not only the A1AO ATP synthase, but in addition the H2:sulfur oxidoreductase complex of I. hospitalis are located in its outermost membrane. Therefore, this membrane is energized and was renamed as “outer cellular membrane” (OCM). Among all prokaryotes possessing two membranes in their cell envelope, I. hospitalis is the first organism with an energized outermost membrane and ATP synthesis outside the cytoplasm. Immunolabeling studies also revealed that the acetyl-CoA synthetase (ACS), an enzyme catalyzing the initial step of the CO2 fixation, is associated with the OCM. Additionally, the PEP carboxylase, malate dehydrogenase, succinic semialdehyde reductase and crotonyl-CoA hydratase/3-hydroxybutyryl- CoA dehydrogenase are localized in the IMC of I. hospitalis. For these enzymes their respective activities were successfully tested. Thus, we conclude that the whole CO2 fixation pathway takes place in the IMC of I. hospitalis. Since DNA and ribosomes are localized in the cytoplasm, energy conservation is separated from information processing and protein biosynthesis in I. hospitalis. This raises questions concerning the transport of metabolites and proteins/enzymes between the compartments of I. hospitalis and a possible ATP/protein transfer to N. equitans. The corresponding necessary transporters have not been annotated or detected so far and might be topic of a new proposal.
Projektbezogene Publikationen (Auswahl)
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A dicarboxylate/4-hydroxybutyrate autotrophic carbon assimilation cycle in the hyperthermophilic Archaeum Ignicoccus hospitalis. PNAS 105:7851-7856 (2008)
Huber H, Gallenberger M, Jahn U, Eylert E, Berg I, Kockelkorn D, Eisenreich W, Fuchs G
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Ignicoccus hospitalis and Nanoarchaeum equitans: Ultrastructure, cell-cell interaction, and 3D reconstruction from serial sections of freeze-substituted cells and by electron cryotomography. Arch Microbiol, 190, 395-408 (2008)
Junglas B, Briegel A, Burghardt T, Walther P, Huber H, Rachel R
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Insight into the proteome of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis: the major cytosolic and membrane proteins. Arch. Microbiol. 190:379-394 (2008)
Burghardt T., Saller M., Gürster S., Müller D., Meyer C., Jahn U., Hochmuth E., Deutzmann R., Siedler F., Babinger P., Wirth R., Huber H., Rachel R.
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Nanoarchaeum equitans and Ignicoccus hospitalis: new insights into a unique, intimate association of two Archaea. J. Bacteriol. 190:1731-1737 (2008)
Jahn U, Gallenberger M, Paper W, Junglas B, Stetter KO, Eisenreich W, Rachel R, Huber H
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Nanoarchaeal origin of histone H3? J. Bact. 191:1092-1096 (2009)
Friedrich-Jahn U, Aigner J, Längst G, Reeve JN, Huber H
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The Iho670 Fibers of Ignicoccus hospitalis: a New Type of Archaeal Cell Surface Appendage. J. Bact. 191:6465-6468 (2009)
Müller D., Meyer C., Gürster S., Küper U., Huber H., Rachel R., Wanner G., Wirth R., Bellack A.
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The interaction of Nanoarchaeum equitans with Ignicoccus hospitalis: proteins in the contact site between two cells. Biochem. Soc. Transactions 37:127-132 (2009)
Burghardt T., Junglas B., Siedler F., Wirth R., Huber H., Rachel R.
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Cloning, purification, crystallization and X-ray crystallographic analysis of Ignicoccus hospitalis neelaredoxin. Acta Crystallographica Section F, 66:605-607 (2010)
Pinho F.G., Romao C.V., Pinto A.F., Saraiva L.M., Huber H., Matias P.M., Teixeira M., Bandeiras T.M.
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Energized outer membrane and spatial separation of metabolic processes in the hyperthermophilic Archaeon Ignicoccus hospitalis. PNAS USA 107:3152-3156 (2010)
Küper U., Meyer C., Müller V., Rachel R., Huber H.
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Ignicoccus hospitalis und sein Weg ATP zu gewinnen. BIOspektrum 16:628-631 (2010)
Küper U., Rachel R., Meyer C, Müller V., Huber H.
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Archaeal symbionts and parasites. Current Opinion in Microbiology 14:1–7 (2011)
Moissl-Eichinger Ch., Huber H.
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Die Feuerkugel und ihr Urzwerg: Rätselhafte Lebensgemeinschaft im Reich der Archaea. BIUZ 41:102-109 (2011)
Huber H., Rachel R.
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Proteomic Characterization of Cellular and Molecular Processes that Enable the Nanoarchaeum equitans-Ignicoccus hospitalis Relationship. PLoS ONE 6(8): e22942. (2011)
Giannone R.J., Huber H., Karpinets, T., Heimerl T., Küper U., Rachel R., Keller M., Hettich R.L., Podar M.
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An AMP-forming acetyl-CoA synthetase in the outermost membrane of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis. J. Bact. 194:1572–1581 (2012)
Mayer F., Küper U., Meyer C., Daxer S., Müller V., Rachel R., Huber H.
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The unusual cell biology of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis. Antonie v. Leeuwenhoek 102:203– 219 (2012)
Huber H., Küper U., Meyer C., Daxer S., Rachel R.
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Life on the edge: Functional genomic response of Ignicoccus hospitalis to the presence of Nanoarchaeum equitans. ISME Journal
Giannone R.J., Wurch L.L., Heimerl T., Martin St., Yang Z., Huber H., Rachel R., Hettich R.L., Podar M.
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Nanoarchaeota. Prokaryotes (2014)
Huber H., Kreuter L.
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Three multiheme cytochromes c from the hyperthermophilic Archaeon Ignicoccus hospitalis: purification, properties and localization. Microbiology 160:1278- 1289 (2014)
Naß B., Pöll U., Langer J., Kreuter L., Küper U., Flechsler J., Heimerl T., Rachel R., Huber H., Kletzin A.
