Huber, Harald and Gallenberger, Martin and Jahn, Ulrike and Eylert, Eva and Berg, Ivan A. and Kockelkorn, Daniel and Eisenreich, Wolfgang and Fuchs, Georg (2008) A dicarboxylate/4-hydroxybutyrate autotrophic carbon assimilation cycle in the hyperthermophilic Archaeum Ignicoccus hospitalis. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 105 (22). pp. 7851-7856. ISSN 0027-8424,
Full text not available from this repository. (Request a copy)Abstract
Ignicoccus hospitalis is an anaerobic, autotrophic, hyperthermophilic Archaeum that serves as a host for the symbiotic/parasitic Archaeum Nanoarchaeum equitans. It uses a yet unsolved autotrophic CO2 fixation pathway that starts from acetyl-CoA (CoA), which is reductively carboxylated to pyruvate. Pyruvate is converted to phosphoenol-pyruvate (PEP), from which glucogenesis as well as oxaloacetate formation branch off. Here, we present the complete metabolic cycle by which the primary CO2 acceptor molecule acetyl-CoA is regenerated. Oxaloacetate is reduced to succinyl-CoA by an incomplete reductive citric acid cycle lacking 2-oxoglutarate dehydrogenase or synthase. Succinyl-CoA is reduced to 4-hydroxybutyrate, which is then activated to the CoA thioester. By using the radical enzyme 4-hydroxybutyryl-CoA dehydratase, 4-hydroxybutyryi-CoA is dehydrated to crotonyl-CoA. Finally, beta-oxidation of crotonyl-CoA leads to two molecules of acetyl-CoA. Thus, the cyclic pathway forms an extra molecule of acetyl-CoA, with pyruvate synthase and PEP carboxylase as the carboxylating enzymes. The proposal is based on in vitro transformation of 4-hydroxybutyrate, detection of all enzyme activities, and in vivo-labeling experiments using [1-C-14]4-hydroxybutyrate,[1,4- C-13(2)], [U-C-13(4)]succinate, or [1-C-13]pyruvate as tracers. The pathway is termed the clicarboxylate/4-hydroxybutyrate cycle. It combines anaerobic metabolic modules to a straightforward and efficient CO2 fixation mechanism.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ARCHAEBACTERIUM THERMOPROTEUS-NEUTROPHILUS; CO2 FIXATION PATHWAYS; CITRIC-ACID CYCLE; 3-HYDROXYPROPIONATE CYCLE; CHLOROFLEXUS-AURANTIACUS; COENZYME-A; SP-NOV; C-13-NMR; ENZYMES; 4-HYDROXYBUTYRYL-COA; 4-hydroxybutyryl-CoA dehydratase; CO2 fixation pathway; acetyl-CoA |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie > Lehrstuhl für Mikrobiologie (Archaeenzentrum) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 29 Oct 2020 11:46 |
| Last Modified: | 29 Oct 2020 11:46 |
| URI: | https://pred.uni-regensburg.de/id/eprint/30750 |
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