Activation of Acetone and Other Simple Ketones in Anaerobic Bacteria

作者：Heider Johann; Schuehle Karola; Frey Jasmin; Schink Bernhard^*

来源：Journal of Molecular Microbiology and Biotechnology, 2016, 26(1-3): 152-164.

DOI：10.1159/000441500

• Carboxylation
• Hydrocarbons
• Ketones
• Energetics
• ATP
• Carbon monoxide
• Thiamine diphosphate
• Formate

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.

• 出版日期2016