title: Activation of Acetone and Other Simple Ketones in Anaerobic Bacteria.
abstract: Acetone and other ketones are activated for subsequent degradation through carboxylation by many nitrate-reducing, phototrophic, and obligately aerobic bacteria. Acetone carboxylation leads to acetoacetate, which is subsequently activated to a thioester and degraded via thiolysis. Two different types of acetone carboxylases have been described, which require either 2 or 4 ATP equivalents as an energy supply for the carboxylation reaction. Both enzymes appear to combine acetone enolphosphate with carbonic phosphate to form acetoacetate. A similar but more complex enzyme is known to carboxylate the aromatic ketone acetophenone, a metabolic intermediate in anaerobic ethylbenzene metabolism in denitrifying bacteria, with simultaneous hydrolysis of 2 ATP to 2 ADP. Obligately anaerobic sulfate-reducing bacteria activate acetone to a four-carbon compound as well, but via a different process than bicarbonate- or CO2-dependent carboxylation. The present evidence indicates that either carbon monoxide or a formyl residue is used as a cosubstrate, and that the overall ATP expenditure of this pathway is substantially lower than in the known acetone carboxylase reactions.
authors.affiliation: Laboratory of Microbiology, LOEWE Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Heider
authors.forename: Karola
authors.initials: K
authors.lastname: Schühle
authors.forename: Jasmin
authors.initials: J
authors.lastname: Frey
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schink
mesh_terms: D000096:Acetone / Q000737:chemistry* / Q000378:metabolism*; D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000145:classification / Q000235:genetics / Q000378:metabolism; D007659:Ketones / Q000737:chemistry* / Q000378:metabolism*; D053858:Metabolic Networks and Pathways
chemical_list: D007659:Ketones; D000096:Acetone; D002262:Carboxy-Lyases; C100963:acetone carboxylase