This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: 2-aminobenzoate degradation (anaerobic)
|Superclasses:||Degradation/Utilization/Assimilation → Aromatic Compounds Degradation → 2-Aminobenzoate Degradation|
Expected Taxonomic Range: Proteobacteria
Four types of aromatic compounds degradation pathways are thought to occur in different types of bacteria:
Aerobic organisms take advantage of the availability of molecular oxygen, and use oxygenases that introduce hydroxyl groups and cleave the aromatic ring. These pathways usually lead to a few central intermediates such as catechol, protocatechuate, and gentisate (see anthranilate degradation I (aerobic)).
Facultative aerobes utilize two types of pathways, depending on the availability of oxygen. When oxygen is present, these organisms use the so-called "hybrid" type of aerobic metabolism for some aromatic compounds, including benzoate, anthranilate and phenylacetate. These pathways use coenzyme A to activate and form thioesters of the substrates, followed by an oxygenase/reductase step to dearomatize (but not cleave) the ring. Cleavage of the dearomatized ring does not require oxygen (see anthranilate degradation II (aerobic)). Under anaerobic conditions, facultative aerobes and phototrophs use a reductive aromatic metabolism. The aromatic compounds are activated by coenzyme A to an active intermediate that can be transformed to important central intermediate such as benzoyl-CoA. Reduction of the aromatic ring of benzoyl-CoA is catalyzed by benzoyl-CoA reductase and is driven by the hydrolysis of 2 ATP molecules (see anthranilate degradation III (anaerobic)).
Strict anaerobes utilize a completely different and not well characterized benzoyl-coenzyme A reductase that does not utilize ATP [Fuchs08].
About This Pathway
Under anaerobic conditions, aromatic compounds have to be dearomatized by means other than oxygenases. A common mechanism involves their activation by coenzyme A to an activated intermediate that can be transformed to the important central intermediate, benzoyl-CoA.
Transformation of anthranilate to benzoyl-CoA is accomplished in two steps, catalyzed by anaerobic aminobenzoate-CoA ligase and by 2-aminobenzoyl-CoA reductase. Cells of Azoarcus evansii grown anaerobically with anthranilate had three different CoA ligases for aromatic compounds, which were named E1, E2 and E3 [Altenschmidt91]. The first one is benzoate-CoA ligase (anaerobic), an enzyme that prefers benzoate as a substrate, although it is active with anthranilate. The two other enzymes preferred the later substrate. However, only one of them, anaerobic aminobenzoate-CoA ligase, is highly expressed. The third enzyme (aerobic 2-aminobenzoate-CoA ligase type 2) appears to be active mostly under aerobic conditions, but apparently is not completely repressed under anaerobic conditions [Altenschmidt91].
For similar pathways leading to benzoyl-CoA, see phenol degradation II (anaerobic) and toluene degradation to benzoyl-CoA (anaerobic). The product benzoyl-CoA enters the central anaerobic benzoyl-CoA degradation pathway (see benzoyl-CoA degradation II (anaerobic)) [Heider98, Lochmeyer92].
Superpathways: anaerobic aromatic compound degradation (Thauera aromatica)
Unification Links: Eawag-BBD-Pathways:abz
Altenschmidt91: Altenschmidt U, Oswald B, Fuchs G (1991). "Purification and characterization of benzoate-coenzyme A ligase and 2-aminobenzoate-coenzyme A ligases from a denitrifying Pseudomonas sp." J Bacteriol 1991;173(17);5494-501. PMID: 1885526
Heider98: Heider J, Boll M, Breese K, Breinig S, Ebenau-Jehle C, Feil U, Gad'on N, Laempe D, Leuthner B, Mohamed ME, Schneider S, Burchhardt G, Fuchs G (1998). "Differential induction of enzymes involved in anaerobic metabolism of aromatic compounds in the denitrifying bacterium Thauera aromatica." Arch Microbiol 1998;170(2);120-31. PMID: 9683649
Lochmeyer92: Lochmeyer C, Koch J, Fuchs G (1992). "Anaerobic degradation of 2-aminobenzoic acid (anthranilic acid) via benzoyl-coenzyme A (CoA) and cyclohex-1-enecarboxyl-CoA in a denitrifying bacterium." J Bacteriol 1992;174(11);3621-8. PMID: 1592816
Altenschmidt92: Altenschmidt U, Fuchs G (1992). "Novel aerobic 2-aminobenzoate metabolism. Purification and characterization of 2-aminobenzoate-CoA ligase, localisation of the gene on a 8-kbp plasmid, and cloning and sequencing of the gene from a denitrifying Pseudomonas sp." Eur J Biochem 205(2);721-7. PMID: 1315272
Coleman08: Coleman JP, Hudson LL, McKnight SL, Farrow JM, Calfee MW, Lindsey CA, Pesci EC (2008). "Pseudomonas aeruginosa PqsA is an anthranilate-coenzyme A ligase." J Bacteriol 190(4);1247-55. PMID: 18083812
Kitagawa13: Kitagawa W, Ozaki T, Nishioka T, Yasutake Y, Hata M, Nishiyama M, Kuzuyama T, Tamura T (2013). "Cloning and heterologous expression of the aurachin RE biosynthesis gene cluster afford a new cytochrome P450 for quinoline N-hydroxylation." Chembiochem 14(9);1085-93. PMID: 23677853
Pistorius11a: Pistorius D, Li Y, Mann S, Muller R (2011). "Unprecedented anthranilate priming involving two enzymes of the acyl adenylating superfamily in aurachin biosynthesis." J Am Chem Soc 133(32);12362-5. PMID: 21770425
Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216
Schuhle01: Schuhle K, Jahn M, Ghisla S, Fuchs G (2001). "Two similar gene clusters coding for enzymes of a new type of aerobic 2-aminobenzoate (anthranilate) metabolism in the bacterium Azoarcus evansii." J Bacteriol 183(18);5268-78. PMID: 11514509
Schuhle03: Schuhle K, Gescher J, Feil U, Paul M, Jahn M, Schagger H, Fuchs G (2003). "Benzoate-coenzyme A ligase from Thauera aromatica: an enzyme acting in anaerobic and aerobic pathways." J Bacteriol 185(16);4920-9. PMID: 12897012
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