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A bicyclic autotrophic CO2 fixation pathway in Chloroflexus aurantiacus.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Herter, Sylvia Fuchs, Georg Bacher, Adelbert Eisenreich, Wolfgang |
| Copyright Year | 2002 |
| Abstract | Phototrophic CO(2) assimilation by the primitive, green eubacterium Chloroflexus aurantiacus has been shown earlier to proceed in a cyclic mode via 3-hydroxypropionate, propionyl-CoA, succinyl-CoA, and malyl-CoA. The metabolic cycle could be closed by cleavage of malyl-CoA affording glyoxylate (the primary CO(2) fixation product) with regeneration of acetyl-CoA serving as the starter unit of the cycle. The pathway of glyoxylate assimilation to form gluconeogenic precursors has not been elucidated to date. We could now show that the incubation of cell extract with a mixture of glyoxylate and [1,2,3-(13)C(3)]propionyl-CoA afforded erythro-beta-[1,2,2'-(13)C(3)]methylmalate and [1,2,2'-(13)C(3)]citramalate. Similar experiments using a partially purified protein fraction afforded erythro-beta-[1,2,2'-(13)C(3)]methylmalyl-CoA and [1,2,2'-(13)C(3)]mesaconyl-CoA. Cell extracts of C. aurantiacus were also shown to catalyze the conversion of citramalate into pyruvate and acetyl-CoA in a succinyl-CoA-dependent reaction. The data suggest that glyoxylate obtained by the cleavage of malyl-CoA can be utilized by condensation with propionyl-CoA affording erythro-beta-methylmalyl-CoA, which is converted to acetyl-CoA and pyruvate. This reaction sequence regenerates acetyl-CoA, which serves as the precursor of propionyl-CoA in the 3-hydroxypropionate cycle. Autotrophic CO(2) fixation proceeds by combination of the 3-hydroxypropionate cycle with the methylmalyl-CoA cycle. The net product of that bicyclic autotrophic CO(2) fixation pathway is pyruvate serving as an universal building block for anabolic reactions. |
| Starting Page | 70 |
| Ending Page | 82 |
| Page Count | 13 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.jbc.org/content/early/2002/04/02/jbc.M201030200.full.pdf |
| Alternate Webpage(s) | http://www.jbc.org/content/277/23/20277.full.pdf |
| PubMed reference number | 11929869v1 |
| Volume Number | 277 |
| Issue Number | 23 |
| Journal | The Journal of biological chemistry |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | 3-Hydroxyacyl CoA Dehydrogenases Acetyl-CoA C-Acetyltransferase Acetyl-CoA C-Acyltransferase Anabolic steroids Carbon Dioxide Chloroflexus Cyanobacteria Deoxyuridine Ephrin Type-B Receptor 1, human Glyoxylates Metabolic Process, Cellular Natural regeneration Propionic acidemia Pyruvate Pyruvates acyl-CoA dehydrogenase carbon fixation by 3-hydroxypropionate cycle citramalate malyl-CoA lyase activity |
| Content Type | Text |
| Resource Type | Article |
