Unusual reactions involved in anaerobic metabolism of phenolic compounds.
Aerobic bacteria use molecular oxygen as a common co-substrate for key enzymes of aromatic metabolism. In contrast, in anaerobes all oxygen-dependent reactions are replaced by a set of alternative enzymatic processes. The anaerobic degradation of phenol to a non-aromatic product involves enzymatic processes that are uniquely found in the aromatic metabolism of anaerobic bacteria: (i) ATP-dependent phenol carboxylation to 4-hydroxybenzoate via a phenylphosphate intermediate (biological Kolbe-Schmitt carboxylation); (ii) reductive dehydroxylation of 4-hydroxybenzoyl-CoA to benzoyl-CoA; and (iii) ATP-dependent reductive dearomatization of the key intermediate benzoyl-CoA in a 'Birch-like' reduction mechanism. This review summarizes the results of recent mechanistic studies of the enzymes involved in these three key reactions.
Boll
Matthias
M
Department of Microbiology, Institute for Biology II, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany. boll@biologie.uni-freiburg.de
Fuchs
Georg
G
D001421:Bacteria, Anaerobic / Q000201:enzymology*; D001426:Bacterial Proteins / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004798:Enzymes / Q000378:metabolism*; D010636:Phenols / Q000378:metabolism*
D001426:Bacterial Proteins; D004798:Enzymes; D010636:Phenols