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.
The enzyme appears in viruses and cellular organisms
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.
PabB produces 4-amino-4-deoxychorismate via a noncovalent 2-amino-2-deoxyisochorismate intermediate. 2-amino-4-deoxyisochorismate is released into solution prior to being rebound and converted to 4-amino-4-deoxyisochorismate in a second PabB-catalyzed reaction. PabB is virtually inactive alone but forms a high affinity complex with E. coli PabA
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. PabB forms a covalent adduct with chorismate
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. PabB forms a covalent adduct with chorismate
PabB produces 4-amino-4-deoxychorismate via a noncovalent 2-amino-2-deoxyisochorismate intermediate. 2-amino-4-deoxyisochorismate is released into solution prior to being rebound and converted to 4-amino-4-deoxyisochorismate in a second PabB-catalyzed reaction. PabB is virtually inactive alone but forms a high affinity complex with E. coli PabA
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
2.25 A crystal structure of PabB that features the 273PIAGT277 motif engaged in several interactions that hold the enzyme in a distorted conformation in the absence of substrate
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