Activation of aromatic acids and aerobic 2-aminobenzoate metabolism in a denitrifyingPseudomonasstrain

✍ Scribed by Klaus Ziegler; Reiner Buder; Jochen Winter; Georg Fuchs

• Book ID: 104764780
• Publisher: Springer
• Year: 1989
• Tongue: English
• Weight: 660 KB
• Volume: 151
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00414434

✦ Synopsis

The initial reactions possibly involved in the aerobic and anaerobic metabolism of aromatic acids by a denitrifying Pseudomonas strain were studied. Several acyl CoA synthetases were found supporting the view that activation of several aromatic acids preceeds degradation. A benzoyl CoA synthetase activity (AMP forming) (apparent Km values of the enzyme from nitrate grown cells: 0.01 mM benzoate, 0.2 mM ATP, 0.2 mM coenzyme A) was present in aerobically grown and anaerobically, nitrate grown cells when benzoate or other aromatic acids were present. In addition to benzoate and fluorobenzoates, also 2-aminobenzoate was activated, albeit with unfavorable Km (0.5 mM 2-aminobenzoate). A 2-aminobenzoyl CoA synthetase (AMP forming) was induced both aerobically and anaerobically with 2-aminobenzoate as growth substrate which had a similar substrate spectrum but a low Km for 2-aminobenzoate (< 0.02 mM). Anaerobic growth on 4hydroxybenzoate induced a 4-hydroxybenzoyl CoA synthetase, and cyclohexanecarboxylate induced another synthetase. In contrast, 3-hydroxybenzoate and phenylacetate grown anaerobic cells appeared not to activate the respective substrates at sufficient rates. Contrary to an earlier report extracts from aerobic and anaerobic 2-aminobenzoate grown cells catalysed a 2-aminobenzoyl CoA-dependent NADH oxidation. This activity was 10-20 times higher in aerobic cells and appeared to be induced by 2aminobenzoate and oxygen. In vitro, 2-aminobenzoyl CoA reduction was dependent on 2-aminobenzoyl CoA, NAD(P)H, and oxygen. A novel mechanism of aerobic 2aminobenzoate degradation is suggested, which proceeds via 2-aminobenzoyl CoA.