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 (aerobic)
|Superclasses:||Degradation/Utilization/Assimilation → Aromatic Compounds Degradation → 2-Aminobenzoate Degradation|
Some taxa known to possess this pathway include : Azoarcus evansii
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
The facultative aerobe Azoarcus evansii processes several aromatic compounds by aerobic pathways that belong to the second type. In these "hybrid" pathways oxygen is used to introduce hydroxyl groups, as in the classic aerobic pathways. However, the aromatic ring is reduced and CoA thioesters are used, as in the anaerobic route. In addition, ring cleavage also does not require oxygen.
The first step in the degradation of anthranilate by this pathway is its activation to a CoA ester, which is catalyzed by 2-aminobenzoate-CoA ligase. This organism has several such enzymes, some of which induced under aerobic conditions, and some under anaerobic conditions. The aerobic alleles are encoded by the almost identical abmG1 and abmG2 genes [Altenschmidt92, Schuhle01]. The activated form anthraniloyl-CoA is then converted by 2-amninobenzoyl-CoA monooxygenase/reductase to a non-aromatic cis-dihydrodiol, 2-amino-5-oxocyclohex-1-enecarboxyl-CoA. The exact nature of the subsequent ring cleavage reaction and the intermediates downstream has not been studied yet [Altenschmidt90].
Relationship Links: Eawag-BBD-Pathways:PART-OF:abz2
Altenschmidt90: Altenschmidt U, Eckerskorn C, Fuchs G (1990). "Evidence that enzymes of a novel aerobic 2-amino-benzoate metabolism in denitrifying Pseudomonas are coded on a small plasmid." Eur J Biochem 194(2);647-53. PMID: 2176602
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
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
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
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
Langkau90: Langkau B, Ghisla S, Buder R, Ziegler K, Fuchs G (1990). "2-Aminobenzoyl-CoA monooxygenase/reductase, a novel type of flavoenzyme. Identification of the reaction products." Eur J Biochem 191(2);365-71. PMID: 2384085
Langkau95: Langkau B, Vock P, Massey V, Fuchs G, Ghisla S (1995). "2-Aminobenzoyl-CoA monooxygenase/reductase. Evidence for two distinct loci catalyzing substrate monooxygenation and hydrogenation." Eur J Biochem 230(2);676-85. PMID: 7607242
Pistorius11: 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
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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