title: Pyrophosphate-Dependent ATP Formation from Acetyl Coenzyme A in Syntrophus aciditrophicus, a New Twist on ATP Formation.
abstract: Syntrophus aciditrophicus is 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 by S. aciditrophicus However, the absence of homologs for phosphate acetyltransferase and acetate kinase in the genome of S. aciditrophicus leaves 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 that S. aciditrophicus uses AMP-forming, acetyl-CoA synthetase (Acs1) for ATP synthesis from acetyl-CoA. acs1 mRNA and Acs1 were abundant in transcriptomes and proteomes, respectively, of S. aciditrophicus grown in pure culture and coculture. Cell extracts of S. aciditrophicus had low or undetectable acetate kinase and phosphate acetyltransferase activities but had high acetyl-CoA synthetase activity under all growth conditions tested. Both Acs1 purified from S. aciditrophicus and 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) in S. aciditrophicus cells support the operation of Acs1 in the acetate-forming direction. Thus, S. aciditrophicus has a unique approach to conserve energy involving pyrophosphate, AMP, acetyl-CoA, and an AMP-forming, acetyl-CoA synthetase.
  
  
  
  Bacteria 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 aciditrophicus apparently 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 that S. aciditrophicus uses 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.
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Kimberly L
authors.initials: KL
authors.lastname: James
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Ríos-Hernández
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Neil Q
authors.initials: NQ
authors.lastname: Wofford
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Housna
authors.initials: H
authors.lastname: Mouttaki
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Sieber
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Cody S
authors.initials: CS
authors.lastname: Sheik
authors.affiliation: Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Hong H
authors.initials: HH
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Erde
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Lars
authors.initials: L
authors.lastname: Rohlin
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Karr
authors.affiliation: Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, USA Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Loo
authors.affiliation: Department of Biological Chemistry, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Ogorzalek Loo
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Hurst
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Gunsalus
authors.affiliation: Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.
authors.forename: Luke I
authors.initials: LI
authors.lastname: Szweda
authors.affiliation: Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, USA mcinerney@ou.edu.
authors.forename: Michael J
authors.identifier: 0000-0002-8054-1389
authors.initials: MJ
authors.lastname: McInerney
mesh_terms: D000085:Acetates / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D003066:Coenzyme A Ligases / Q000378:metabolism*; D020564:Deltaproteobacteria / Q000201:enzymology* / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism*; D020869:Gene Expression Profiling; D055442:Metabolome; D020543:Proteome / Q000032:analysis
chemical_list: D000085:Acetates; D011756:Diphosphates; D020543:Proteome; C107241:diphosphoric acid; D000105:Acetyl Coenzyme A; D000255:Adenosine Triphosphate; D003066:Coenzyme A Ligases; C561832:Acsl1 protein, rat