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Literature summary extracted from

  • Dong, L.; Liu, Y.
    Comparative studies of the catalytic mechanisms of two chorismatases CH-fkbo and CH-Hyg5 (2017), Proteins, 85, 1146-1158 .
    View publication on PubMed

Inhibitors

EC Number Inhibitors Comment Organism Structure
3.3.2.13 3-(2-carboxyethyl)benzoate
-
 Streptomyces hygroscopicus

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
3.3.2.13 chorismate + H2O Streptomyces hygroscopicus
-
 (4R,5R)-4,5-dihydroxycyclohexa-1(6),2-diene-1-carboxylate + pyruvate
-
 ?
4.1.3.45 chorismate Streptomyces hygroscopicus
-
 3-hydroxybenzoate + pyruvate
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
3.3.2.13 Streptomyces hygroscopicus Q9KID9
-
-
4.1.3.45 Streptomyces hygroscopicus O30478
-
-

Reaction

EC Number Reaction Comment Organism Reaction ID
3.3.2.13 chorismate + H2O = (4R,5R)-4,5-dihydroxycyclohexa-1(6),2-diene-1-carboxylate + pyruvate catalytic mechanism, the two carboxyl groups of chorismate form a H-bond network with residues R228, Y215, Y155, and R162. These H-bonds are maintained during the whole catalytic process, which may play a role in stabilizing the negative charged substrate. The protonated E338 builds a strong H-bond with the 4-OH of chorismate. The distance between HA of E338 and C3' of chorismate is 4.00 A. Two water molecules enter the reactive center, which may function as mediators in the catalytic reaction. The reaction steps are protonation of methylene group, followed by nucleophilic attack of carbocation by (activated) water molecule W1, and cleavage of C2'-O8 bond Streptomyces hygroscopicus
a
4.1.3.45 chorismate = 3-hydroxybenzoate + pyruvate the reaction of Hyg5 undergoes an arene oxide mechanism. First is, accompanied by the protonation of the methylene group, the C3-O8 bond cleavage, a concerted but asynchronous process with an energy barrier of 26.3 kcal/mol. The subsequent arene oxide formation step is quite rapid with an energy barrier of 3.7 kcal/mol. The last step is the selective ring-opening directed by C327. Residue E334 plays key roles in the formation and opening of the arene oxide intermediate Streptomyces hygroscopicus
a

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
3.3.2.13 chorismate + H2O
-
 Streptomyces hygroscopicus (4R,5R)-4,5-dihydroxycyclohexa-1(6),2-diene-1-carboxylate + pyruvate
-
 ?
4.1.3.45 chorismate
-
 Streptomyces hygroscopicus 3-hydroxybenzoate + pyruvate
-
 ?

Synonyms

EC Number Synonyms Comment Organism
3.3.2.13 CH-fkbo
-
 Streptomyces hygroscopicus
3.3.2.13 fkbO
-
 Streptomyces hygroscopicus
4.1.3.45 CH-Hyg5
-
 Streptomyces hygroscopicus
4.1.3.45 chorismatase/3-hydroxybenzoate synthase
-
 Streptomyces hygroscopicus

General Information

EC Number General Information Comment Organism
3.3.2.13 additional information structure of Fkbo-substrate complex, the solvated model of CH-Fkbo is optimized to calculate the catalytic mechanism. In the reactant structure, the substrate chorismate takes the similar binding model as inhibitor 3-(2-carboxyethyl)benzoate in crystal structure and adopts a trans-pseudodiaxial conformation. The structure of Streptomyces hygroscopicus chorismatase CH-Hyg5 is very similar to that of Streptomyces hygroscopicus chorismatase CH-Fkbo, all amino acid residues in the active site are the same except residues G240Hyg5 (A244Fkb8) and C327Hyg5 (A331Fkb8) are the same. The optimized active site structure of Hyg5 complex is superpositioned with that of Fkbo, overview. Two nonconserved active site residues are responsible for the different reaction mechanism of CH-Fkbo and CH-Hyg5. In CH-Hyg5, the lack of methyl in G240Hyg5 leads to the different conformation of the side chain of E334 (or E338) in Hyg5 and Fkbo. This small change eventually decreases the ESP charge of C3 atom of the substrate, which facilitates the cleavage of C3-O8 bond in Hyg5. Furthermore, C327Hyg5 is involved in the selective product formation in Hyg5 enzyme Streptomyces hygroscopicus
4.1.3.45 additional information the structure of Streptomyces hygroscopicus chorismatase CH-Hyg5 is very similar to that of Streptomyces hygroscopicus chorismatase CH-Fkbo, all amino acid residues in the active site are the same except residues G240Hyg5 (A244Fkb8) and C327Hyg5 (A331Fkb8) are the same. The optimized active site structure of Hyg5 complex is superpositioned with that of Fkbo, overview. Two nonconserved active site residues are responsible for the different reaction mechanism of CH-Fkbo and CH-Hyg5. In CH-Hyg5, the lack of methyl in G240Hyg5 leads to the different conformation of the side chain of E334 (or E338) in Hyg5 and Fkbo. This small change eventually decreases the ESP charge of C3 atom of the substrate, which facilitates the cleavage of C3-O8 bond in Hyg5. Furthermore, C327Hyg5 is involved in the selective product formation in Hyg5 enzyme Streptomyces hygroscopicus