| Both forward and reverse TCA cycles operate in green sulfur bacteria. | |
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MedLine Citation:
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PMID: 20650900 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The anoxygenic green sulfur bacteria (GSBs) assimilate CO(2) autotrophically through the reductive (reverse) tricarboxylic acid (RTCA) cycle. Some organic carbon sources, such as acetate and pyruvate, can be assimilated during the phototrophic growth of the GSBs, in the presence of CO(2) or HCO(3)(-). It has not been established why the inorganic carbonis required for incorporating organic carbon for growth and how the organic carbons are assimilated. In this report, we probed carbon flux during autotrophic and mixotrophic growth of the GSB Chlorobaculum tepidum. Our data indicate the following: (a) the RTCA cycle is active during autotrophic and mixotrophic growth; (b) the flux from pyruvate to acetyl-CoA is very low and acetyl-CoA is synthesized through the RTCA cycle and acetate assimilation; (c) pyruvate is largely assimilated through the RTCA cycle; and (d) acetate can be assimilated via both of the RTCA as well as the oxidative (forward) TCA (OTCA) cycle. The OTCA cycle revealed herein may explain better cell growth during mixotrophic growth with acetate, as energy is generated through the OTCA cycle. Furthermore, the genes specific for the OTCA cycle are either absent or down-regulated during phototrophic growth, implying that the OTCA cycle is not complete, and CO(2) is required for the RTCA cycle to produce metabolites in the TCA cycle. Moreover, CO(2) is essential for assimilating acetate and pyruvate through the CO(2)-anaplerotic pathway and pyruvate synthesis from acetyl-CoA. |
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Authors:
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Kuo-Hsiang Tang; Robert E Blankenship |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2010-07-22 |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 285 ISSN: 1083-351X ISO Abbreviation: J. Biol. Chem. Publication Date: 2010 Nov |
Date Detail:
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Created Date: 2010-11-08 Completed Date: 2011-02-09 Revised Date: 2011-11-14 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: United States |
Other Details:
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Languages: eng Pagination: 35848-54 Citation Subset: IM |
Affiliation:
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Department of Biology and Chemistry, Washington University, St Louis, Missouri 63130, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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ATP Citrate (pro-S)-Lyase
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genetics,
metabolism Acetate Kinase / genetics, metabolism Acetates / chemistry, metabolism Acetyl Coenzyme A / chemistry, metabolism Autotrophic Processes Bacterial Proteins / genetics, metabolism* Biomass Carbon / metabolism Carbon Isotopes Chlorobi / genetics, growth & development, metabolism* Citric Acid Cycle* Coenzyme A Ligases / genetics, metabolism Gene Expression Regulation, Bacterial Lactic Acid / chemistry, metabolism Metabolic Networks and Pathways Models, Biological Molecular Structure Pyruvic Acid / chemistry, metabolism Reverse Transcriptase Polymerase Chain Reaction |
| Grant Support | |
ID/Acronym/Agency:
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R01-GM57391/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Acetates; 0/Bacterial Proteins; 0/Carbon Isotopes; 127-17-3/Pyruvic Acid; 50-21-5/Lactic Acid; 72-89-9/Acetyl Coenzyme A; 7440-44-0/Carbon; EC 2.3.3.8/ATP Citrate (pro-S)-Lyase; EC 2.7.2.1/Acetate Kinase; EC 6.2.1.-/Coenzyme A Ligases; EC 6.2.1.13/acetate-CoA ligase (ADP-forming) |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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