EC 1.3.8.16     
Accepted name: 2-amino-4-deoxychorismate dehydrogenase
Reaction: (2S)-2-amino-4-deoxychorismate + FMN = 3-(1-carboxyvinyloxy)anthranilate + FMNH2
Glossary: (2S)-2-amino-4-deoxychorismate = (2S,3S)-3-(1-carboxyvinyloxy)-2,3-dihydroanthranilate
3-enolpyruvoylanthranilate = 3-(1-carboxyvinyloxy)anthranilate
Other name(s): ADIC dehydrogenase; 2-amino-2-deoxyisochorismate dehydrogenase; SgcG
Systematic name: (2S)-2-amino-4-deoxychorismate:FMN oxidoreductase
Comments: The sequential action of EC 2.6.1.86, 2-amino-4-deoxychorismate synthase and this enzyme leads to the formation of the benzoxazolinate moiety of the enediyne antitumour antibiotic C-1027 [1,2].
References:
1.  Van Lanen, S.G., Lin, S. and Shen, B. Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism. Proc. Natl. Acad. Sci. USA 105 (2008) 494–499. [PMID: 18182490]
2.  Yu, L., Mah, S., Otani, T. and Dedon, P. The benzoxazolinate of C-1027 confers intercalative DNA binding. J. Am. Chem. Soc. 117 (1995) 8877–8878.
[EC 1.3.8.16 created 2008 as 1.3.99.24, transferred 2020 to EC 1.3.8.16.]
 
 
EC 1.3.99.24      
Transferred entry: 2-amino-4-deoxychorismate dehydrogenase. Now EC 1.3.8.16, 2-amino-4-deoxychorismate dehydrogenase
[EC 1.3.99.24 created 2008, deleted 2020]
 
 
EC 2.2.1.9     
Accepted name: 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylic-acid synthase
Reaction: isochorismate + 2-oxoglutarate = 5-enolpyruvoyl-6-hydroxy-2-succinyl-cyclohex-3-ene-1-carboxylate + CO2
Other name(s): SEPHCHC synthase; MenD
Systematic name: isochorismate:2-oxoglutarate 4-oxopentanoatetransferase (decarboxylating)
Comments: Requires Mg2+ for maximal activity. This enzyme is involved in the biosynthesis of vitamin K2 (menaquinone). In most anaerobes and all Gram-positive aerobes, menaquinone is the sole electron transporter in the respiratory chain and is essential for their survival. It had previously been thought that the products of the reaction were (1R,6R)-6-hydroxy-2-succinylcyclohexa-2,4-diene-1-carboxylate (SHCHC), pyruvate and CO2 but it is now known that two separate enzymes are involved: this enzyme and EC 4.2.99.20, 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase. Under basic conditions, the product can spontaneously lose pyruvate to form SHCHC.
References:
1.  Jiang, M., Cao, Y., Guo, Z.F., Chen, M., Chen, X. and Guo, Z. Menaquinone biosynthesis in Escherichia coli: identification of 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate as a novel intermediate and re-evaluation of MenD activity. Biochemistry 46 (2007) 10979–10989. [PMID: 17760421]
[EC 2.2.1.9 created 2008 (EC 2.5.1.64 created 2003, part-incorporated 2008)]
 
 
EC 2.5.1.64      
Transferred entry: 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase. The reaction that was attributed to this enzyme is now known to be catalysed by two separate enzymes: EC 2.2.1.9 (2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylic-acid synthase) and EC 4.2.99.20 (2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase)
[EC 2.5.1.64 created 2003, deleted 2008]
 
 
EC 2.6.1.86     
Accepted name: 2-amino-4-deoxychorismate synthase
Reaction: (2S)-2-amino-4-deoxychorismate + L-glutamate = chorismate + L-glutamine
Glossary: (2S)-2-amino-4-deoxychorismate = (2S,3S)-3-(1-carboxyvinyloxy)-2,3-dihydroanthranilate
Other name(s): ADIC synthase; 2-amino-2-deoxyisochorismate synthase; SgcD
Systematic name: (2S)-2-amino-4-deoxychorismate:2-oxoglutarate aminotransferase
Comments: Requires Mg2+. The reaction occurs in the reverse direction to that shown above. In contrast to most anthranilate-synthase I (ASI) homologues, this enzyme is not inhibited by tryptophan. In Streptomyces globisporus, the sequential action of this enzyme and EC 1.3.99.24, 2-amino-4-deoxychorismate dehydrogenase, leads to the formation of the benzoxazolinate moiety of the enediyne antitumour antibiotic C-1027 [1,2]. In certain Pseudomonads the enzyme participates in the biosynthesis of phenazine, a precursor for several compounds with antibiotic activity [3,4].
References:
1.  Van Lanen, S.G., Lin, S. and Shen, B. Biosynthesis of the enediyne antitumor antibiotic C-1027 involves a new branching point in chorismate metabolism. Proc. Natl. Acad. Sci. USA 105 (2008) 494–499. [PMID: 18182490]
2.  Yu, L., Mah, S., Otani, T. and Dedon, P. The benzoxazolinate of C-1027 confers intercalative DNA binding. J. Am. Chem. Soc. 117 (1995) 8877–8878.
3.  McDonald, M., Mavrodi, D.V., Thomashow, L.S. and Floss, H.G. Phenazine biosynthesis in Pseudomonas fluorescens: branchpoint from the primary shikimate biosynthetic pathway and role of phenazine-1,6-dicarboxylic acid. J. Am. Chem. Soc. 123 (2001) 9459–9460. [PMID: 11562236]
4.  Laursen, J.B. and Nielsen, J. Phenazine natural products: biosynthesis, synthetic analogues, and biological activity. Chem. Rev. 104 (2004) 1663–1686. [PMID: 15008629]
[EC 2.6.1.86 created 2008]
 
 
EC 2.6.1.123     
Accepted name: 4-amino-4-deoxychorismate synthase (2-amino-4-deoxychorismate-forming)
Reaction: chorismate + 2 L-glutamine + H2O = 4-amino-4-deoxychorismate + 2 L-glutamate + ammonia (overall reaction)
(1a) 2 L-glutamine + 2 H2O = 2 L-glutamate + 2 NH3
(1b) chorismate + NH3 = (2S)-2-amino-4-deoxychorismate + H2O
(1c) (2S)-2-amino-4-deoxychorismate + NH3 = 4-amino-4-deoxychorismate + NH3
Other name(s): ADCS (ambiguous); ADC synthase (ambiguous); pabAB (gene names)
Systematic name: chorismate:L-glutamine aminotransferase (2-amino-4-deoxychorismate-forming)
Comments: The enzyme, characterized from the bacterium Bacillus subtilis, is a heterodimer. The PabA subunit acts successively on two molecules of L-glutamine, hydrolysing each to L-glutamate and ammonia (cf. EC 3.5.1.2, glutaminase). The ammonia molecules are channeled to the active site of PabB, which catalyses the formation of 4-amino-4-deoxychorismate from chorismate in two steps via the intermediate 2-amino-4-deoxychorismate. cf. EC 2.6.1.85, aminodeoxychorismate synthase.
References:
1.  Schadt, H.S., Schadt, S., Oldach, F. and Sussmuth, R.D. 2-Amino-2-deoxyisochorismate is a key intermediate in Bacillus subtilis p-aminobenzoic acid biosynthesis. J. Am. Chem. Soc. 131 (2009) 3481–3483. [PMID: 19275258]
2.  Bera, A.K., Atanasova, V., Dhanda, A., Ladner, J.E. and Parsons, J.F. Structure of aminodeoxychorismate synthase from Stenotrophomonas maltophilia. Biochemistry 51 (2012) 10208–10217. [PMID: 23230967]
[EC 2.6.1.123 created 2021]
 
 
EC 3.3.2.1     
Accepted name: isochorismatase
Reaction: isochorismate + H2O = (2S,3S)-2,3-dihydroxy-2,3-dihydrobenzoate + pyruvate
Glossary: isochorismate = (5S,6S)-5-[(1-carboxyethenyl)oxy]-6-hydroxycyclohexa-1,3-diene-1-carboxylate
Other name(s): 2,3-dihydro-2,3-dihydroxybenzoate synthase; 2,3-dihydroxy-2,3-dihydrobenzoate synthase; 2,3-dihydroxy-2,3-dihydrobenzoic synthase
Systematic name: isochorismate pyruvate-hydrolase
Comments: The enzyme is involved in the biosynthesis of several siderophores, such as 2,3-dihydroxybenzoylglycine, enterobactin, bacillibactin, and vibriobactin.
References:
1.  Young, I.G. and Gibson, F. Regulation of the enzymes involved in the biosynthesis of 2,3-dihydroxybenzoic acid in Aerobacter aerogenes and Escherichia coli. Biochim. Biophys. Acta 177 (1969) 401–411. [PMID: 4306838]
[EC 3.3.2.1 created 1972]
 
 
EC 4.2.99.21     
Accepted name: isochorismate lyase
Reaction: isochorismate = salicylate + pyruvate
Other name(s): salicylate biosynthesis protein pchB; pyochelin biosynthetic protein PchB; isochorismate pyruvate lyase
Systematic name: isochorismate pyruvate-lyase (salicylate-forming)
Comments: This enzyme is part of the pathway of salicylate formation from chorismate, and forms an integral part of pathways that produce salicylate-derived siderophores, such as pyochelin and yersiniabactin.
References:
1.  Serino, L., Reimmann, C., Baur, H., Beyeler, M., Visca, P. and Haas, D. Structural genes for salicylate biosynthesis from chorismate in Pseudomonas aeruginosa. Mol. Gen. Genet. 249 (1995) 217–228. [PMID: 7500944]
2.  Kerbarh, O., Ciulli, A., Howard, N.I. and Abell, C. Salicylate biosynthesis: overexpression, purification, and characterization of Irp9, a bifunctional salicylate synthase from Yersinia enterocolitica. J. Bacteriol. 187 (2005) 5061–5066. [PMID: 16030197]
[EC 4.2.99.21 created 2010]
 
 
EC 5.4.4.2     
Accepted name: isochorismate synthase
Reaction: chorismate = isochorismate
Other name(s): MenF
Systematic name: isochorismate hydroxymutase
Comments: Requires Mg2+. The reaction is reversible.
References:
1.  Young, I.G. and Gibson, F. Regulation of the enzymes involved in the biosynthesis of 2,3-dihydroxybenzoic acid in Aerobacter aerogenes and Escherichia coli. Biochim. Biophys. Acta 177 (1969) 401–411. [PMID: 4306838]
2.  van Tegelen, L.J., Moreno, P.R., Croes, A.F., Verpoorte, R. and Wullems, G.J. Purification and cDNA cloning of isochorismate synthase from elicited cell cultures of Catharanthus roseus. Plant Physiol. 119 (1999) 705–712. [PMID: 9952467]
3.  Dahm, C., Müller, R., Schulte, G., Schmidt, K. and Leistner, E. The role of isochorismate hydroxymutase genes entC and menF in enterobactin and menaquinone biosynthesis in Escherichia coli. Biochim. Biophys. Acta 1425 (1998) 377–386. [PMID: 9795253]
4.  Daruwala, R., Kwon, O., Meganathan, R. and Hudspeth, M.E. A new isochorismate synthase specifically involved in menaquinone (vitamin K2) biosynthesis encoded by the menF gene. FEMS Microbiol. Lett. 140 (1996) 159–163. [PMID: 8764478]
[EC 5.4.4.2 created 1972 as EC 5.4.99.6, transferred 2003 to EC 5.4.4.2]
 
 
EC 5.4.99.6      
Transferred entry: isochorismate synthase. Now EC 5.4.4.2, isochorismate synthase
[EC 5.4.99.6 created 1972, deleted 2003]
 
 
EC 6.2.1.71     
Accepted name: 2,3-dihydroxybenzoate—[aryl-carrier protein] ligase
Reaction: ATP + 2,3-dihydroxybenzoate + holo-[aryl-carrier protein] = AMP + diphosphate + 2,3-dihydroxybenzoyl-[aryl-carrier protein] (overall reaction)
(1a) ATP + 2,3-dihydroxybenzoate = diphosphate + (2,3-dihydroxybenzoyl)adenylate
(1b) (2,3-dihydroxybenzoyl)adenylate + holo-[aryl-carrier protein] = AMP + 2,3-dihydroxybenzoyl-[aryl-carrier protein]
Other name(s): entE (gene name); vibE (gene name); dhbE (gene name); angE (gene name)
Systematic name: 2,3-dihydroxybenzoate:[aryl-carrier protein] ligase (AMP-forming)
Comments: The adenylation domain of the enzyme catalyses the activation of 2,3-dihydroxybenzoate to (2,3-dihydroxybenzoyl)adenylate, followed by the transfer the activated compound to the free thiol of a phosphopantetheine arm of an aryl-carrier protein domain of a specific non-ribosomal peptide synthase. For example, the EntE enzyme of Escherichia coli is part of the enterobactin synthase complex, the VibE enzyme of Vibrio cholerae is part of the vibriobactin synthase complex, and the DhbE enzyme of Bacillus subtilis is part of the bacillibactin synthase complex.
References:
1.  Gehring, A.M., Bradley, K.A. and Walsh, C.T. Enterobactin biosynthesis in Escherichia coli: isochorismate lyase (EntB) is a bifunctional enzyme that is phosphopantetheinylated by EntD and then acylated by EntE using ATP and 2,3-dihydroxybenzoate. Biochemistry 36 (1997) 8495–8503. [PMID: 9214294]
2.  Wyckoff, E.E., Stoebner, J.A., Reed, K.E. and Payne, S.M. Cloning of a Vibrio cholerae vibriobactin gene cluster: identification of genes required for early steps in siderophore biosynthesis. J. Bacteriol. 179 (1997) 7055–7062. [PMID: 9371453]
3.  Ehmann, D.E., Shaw-Reid, C.A., Losey, H.C. and Walsh, C.T. The EntF and EntE adenylation domains of Escherichia coli enterobactin synthetase: sequestration and selectivity in acyl-AMP transfers to thiolation domain cosubstrates. Proc. Natl. Acad. Sci. USA 97 (2000) 2509–2514. [PMID: 10688898]
4.  Keating, T.A., Marshall, C.G. and Walsh, C.T. Vibriobactin biosynthesis in Vibrio cholerae: VibH is an amide synthase homologous to nonribosomal peptide synthetase condensation domains. Biochemistry 39 (2000) 15513–15521. [PMID: 11112537]
5.  May, J.J., Wendrich, T.M. and Marahiel, M.A. The dhb operon of Bacillus subtilis encodes the biosynthetic template for the catecholic siderophore 2,3-dihydroxybenzoate-glycine-threonine trimeric ester bacillibactin. J. Biol. Chem. 276 (2001) 7209–7217. [PMID: 11112781]
6.  Sikora, A.L., Wilson, D.J., Aldrich, C.C. and Blanchard, J.S. Kinetic and inhibition studies of dihydroxybenzoate-AMP ligase from Escherichia coli. Biochemistry 49 (2010) 3648–3657. [PMID: 20359185]
7.  Khalil, S. and Pawelek, P.D. Enzymatic adenylation of 2,3-dihydroxybenzoate is enhanced by a protein-protein interaction between Escherichia coli 2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase (EntA) and 2,3-dihydroxybenzoate-AMP ligase (EntE). Biochemistry 50 (2011) 533–545. [PMID: 21166461]
[EC 6.2.1.71 created 2021 (EC 2.7.7.58 created 1992, incorporated 2021)]