title: EPR properties of the Ni-Fe-C center in an enzyme complex with carbon monoxide dehydrogenase activity from acetate-grown Methanosarcina thermophila. Evidence that acetyl-CoA is a physiological substrate.
abstract: The carbon monoxide dehydrogenase complex from acetate-grown Methanosarcina thermophila was further studied by EPR spectroscopy. The as purified enzyme exhibited no paramagnetic species at 113 K; however, enzyme reduced with CO exhibited a complex EPR spectrum comprised of two paramagnetic species with g values of g1 = 2.089, g2 = 2.078, and g3 = 2.030 (signal I) and g1 = 2.057, g2 = 2.049, and g3 = 2.027 (signal II). Isotopic substitution with 61Ni, 57Fe, or 13CO resulted in broadening of the EPR spectra indicating a Ni-Fe-C spin-coupled complex. Pure signal II was obtained following treatment of the CO-reduced enzyme with acetyl-CoA but not by addition of acetyl phosphate or CoASH. Acetate-grown cells were highly enriched in acetate kinase (EC 2.7.2.1) and CoASH-dependent phosphotransacetylase (EC 2.3.1.8) activities. These results suggest acetyl-CoA is a physiological substrate for the carbon monoxide dehydrogenase complex synthesized in acetate-grown cells of M. thermophila.
authors.affiliation: Department of Anaerobic Microbiology, Virginia Polytechnic Institute, State University, Blacksburg 24061.
authors.forename: K C
authors.initials: KC
authors.lastname: Terlesky
authors.forename: M J
authors.initials: MJ
authors.lastname: Barber
authors.forename: D J
authors.initials: DJ
authors.lastname: Aceti
authors.forename: J G
authors.initials: JG
authors.lastname: Ferry
mesh_terms: D000084:Acetate Kinase / Q000378:metabolism; D000085:Acetates / Q000378:metabolism*; D019342:Acetic Acid; D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D002244:Carbon; D003065:Coenzyme A / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D019605:Euryarchaeota / Q000201:enzymology*; D007501:Iron; D008872:Microwaves; D009097:Multienzyme Complexes; D009532:Nickel; D010755:Organophosphates / Q000378:metabolism; D010709:Phosphate Acetyltransferase / Q000378:metabolism
chemical_list: D000085:Acetates; D009097:Multienzyme Complexes; D010755:Organophosphates; C011632:acetyl phosphate; D000105:Acetyl Coenzyme A; D002244:Carbon; D009532:Nickel; D007501:Iron; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; D010709:Phosphate Acetyltransferase; D000084:Acetate Kinase; D019342:Acetic Acid; D003065:Coenzyme A