Transferases;
Transferring nitrogenous groups;
Transaminases
BRITE hierarchy

chorismate:L-glutamine aminotransferase (2-amino-4-deoxychorismate-forming)

chorismate + 2 L-glutamine + H2O = 4-amino-4-deoxychorismate + 2 L-glutamate + NH3 (overall reaction) [RN:R12939];
(1a) 2 L-glutamine + 2 H2O = 2 L-glutamate + 2 NH3 [RN:R00256];
(1b) chorismate + NH3 = (2S)-2-amino-4-deoxychorismate + H2O [RN:R12937];
(1c) (2S)-2-amino-4-deoxychorismate + NH3 = 4-amino-4-deoxychorismate + NH3 [RN:R12938]

R00256 R12937 R12938 R12939
Reaction

chorismate [CPD:C00251];
L-glutamine [CPD:C00064];
H2O [CPD:C00001];
NH3 [CPD:C00014];
(2S)-2-amino-4-deoxychorismate [CPD:C18054]

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.

EC 2.6.1.123 created 2021

1  [PMID:19275258]

2  [PMID:23230967]