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Title: Pyrophosphate-Dependent ATP Formation from Acetyl Coenzyme A in Syntrophus aciditrophicus , a New Twist on ATP Formation

Syntrophus aciditrophicusis a model syntrophic bacterium that degrades key intermediates in anaerobic decomposition, such as benzoate, cyclohexane-1-carboxylate, and certain fatty acids, to acetate when grown with hydrogen-/formate-consuming microorganisms. ATP formation coupled to acetate production is the main source for energy conservation byS. aciditrophicus. However, the absence of homologs for phosphate acetyltransferase and acetate kinase in the genome ofS. aciditrophicusleaves it unclear as to how ATP is formed, as most fermentative bacteria rely on these two enzymes to synthesize ATP from acetyl coenzyme A (CoA) and phosphate. Here, we combine transcriptomic, proteomic, metabolite, and enzymatic approaches to show thatS. aciditrophicususes AMP-forming, acetyl-CoA synthetase (Acs1) for ATP synthesis from acetyl-CoA.acs1mRNA and Acs1 were abundant in transcriptomes and proteomes, respectively, ofS. aciditrophicusgrown in pure culture and coculture. Cell extracts ofS. aciditrophicushad low or undetectable acetate kinase and phosphate acetyltransferase activities but had high acetyl-CoA synthetase activity under all growth conditions tested. Both Acs1 purified fromS. aciditrophicusand recombinantly produced Acs1 catalyzed ATP and acetate formation from acetyl-CoA, AMP, and pyrophosphate. High pyrophosphate levels and a high AMP-to-ATP ratio (5.9 ± 1.4) inS. aciditrophicuscells support the operation of Acs1 in the acetate-forming direction. Thus,S. aciditrophicushas a unique approach to conserve energy involving pyrophosphate, AMP, acetyl-CoA, and an AMP-forming, acetyl-CoA synthetase. We find bacteriamore » use two enzymes, phosphate acetyltransferase and acetate kinase, to make ATP from acetyl-CoA, while acetate-forming archaea use a single enzyme, an ADP-forming, acetyl-CoA synthetase, to synthesize ATP and acetate from acetyl-CoA.Syntrophus aciditrophicusapparently relies on a different approach to conserve energy during acetyl-CoA metabolism, as its genome does not have homologs to the genes for phosphate acetyltransferase and acetate kinase. Here, we show thatS. aciditrophicususes an alternative approach, an AMP-forming, acetyl-CoA synthetase, to make ATP from acetyl-CoA. AMP-forming, acetyl-CoA synthetases were previously thought to function only in the activation of acetate to acetyl-CoA.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [1] ;  [5] ;  [6] ;  [2] ;  [4] ;  [7] ;  [1]
  1. Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology and Plant Biology
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Chemistry and Biochemistry
  4. Univ. of California, Los Angeles, CA (United States). Dept. of Microbiology, Immunology and Molecular Genetics
  5. Univ. of California, Los Angeles, CA (United States). Dept. of Chemistry and Biochemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  7. Oklahoma Medical Research Foundation, Oklahoma City, OK (United States). Aging and Metabolism Research Program
Publication Date:
OSTI Identifier:
1324038
Grant/Contract Number:
AC05-00OR22725; FG02-96ER20214; FC02-02ER63421; R01GM085402; FC02-02ER6342; FG02-08ER64689
Type:
Accepted Manuscript
Journal Name:
mBio (Online)
Additional Journal Information:
Journal Name: mBio (Online); Journal Volume: 7; Journal Issue: 4; Journal ID: ISSN 2150-7511
Publisher:
American Society for Microbiology
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Institutes of Health (NIH);USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES