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UniProt functional annotation for P05041 | ||
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| UniProt code: P05041. |
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| Organism: | |
Escherichia coli (strain K12). |
| Taxonomy: | |
Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales; Enterobacteriaceae; Escherichia. |
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| Function: | |
Part of a heterodimeric complex that catalyzes the two-step biosynthesis of 4-amino-4-deoxychorismate (ADC), a precursor of p- aminobenzoate (PABA) and tetrahydrofolate. In the first step, a glutamine amidotransferase (PabA) generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by aminodeoxychorismate synthase (PabB) to produce ADC. PabB, in the absence of PabA, can catalyze the formation of ADC in the presence of exogenous ammonia. {ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:2251281, ECO:0000269|PubMed:4914080}. |
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| Catalytic activity: | |
Reaction=chorismate + L-glutamine = 4-amino-4-deoxychorismate + L- glutamate; Xref=Rhea:RHEA:11672, ChEBI:CHEBI:29748, ChEBI:CHEBI:29985, ChEBI:CHEBI:58359, ChEBI:CHEBI:58406; EC=2.6.1.85; Evidence={ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:2251281}; |
| Cofactor: | |
Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000269|PubMed:2251281}; |
| Activity regulation: | |
Inhibited by 6-diazo-5-oxo-L-norleucine (DON). The inhibition is competitive with glutamine but uncompetitive with chorismate. Also inhibited by 2-fluorochorismate. {ECO:0000269|PubMed:15303852, ECO:0000269|PubMed:7592344}. |
| Biophysicochemical properties: | |
Kinetic parameters: KM=4.2 uM for chorismate (with PabA and glutamine as the amino donor at pH 7.5) {ECO:0000269|PubMed:14982443, ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:7592344}; KM=18.6 uM for chorismate (with PabA and ammonia as the amino donor at pH 7.5) {ECO:0000269|PubMed:14982443, ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:7592344}; KM=71 uM for chorismate {ECO:0000269|PubMed:14982443, ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:7592344}; KM=75 uM for chorismate (with PabA) {ECO:0000269|PubMed:14982443, ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:7592344}; KM=379 uM for chorismate (with PabA and ammonia) {ECO:0000269|PubMed:14982443, ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:7592344}; KM=388 uM for chorismate (with ammonia) {ECO:0000269|PubMed:14982443, ECO:0000269|PubMed:16605270, ECO:0000269|PubMed:7592344}; |
| Pathway: | |
Cofactor biosynthesis; tetrahydrofolate biosynthesis; 4- aminobenzoate from chorismate: step 1/2. |
| Subunit: | |
Monomer. Heterodimer consisting of two non-identical subunits: a glutamine amidotransferase subunit (PabA) and a aminodeoxychorismate synthase subunit (PabB). {ECO:0000269|PubMed:11841211, ECO:0000269|PubMed:8679677}. |
| Disruption phenotype: | |
Cells lacking this gene do not produce 4- aminobenzoate. {ECO:0000269|PubMed:4914080}. |
| Miscellaneous: | |
In this enzymatic reaction the C4 hydroxy group of chorismate is replaced by addition of a nucleophile at the C2 position. The nucleophile is the epsilon-amino group of lysine 274 transiently binds to C2 of chorismate (PubMed:16605270). PabB contains a tryptophan (Trp) molecule deeply embedded in a binding pocket. Trp which cannot be dissociated without denaturation of PabB, may play a structural role in the enzyme since it has no effect on the enzymic synthesis of aminodeoxychorismate (PubMed:11841211). {ECO:0000305|PubMed:11841211, ECO:0000305|PubMed:16605270}. |
| Similarity: | |
Belongs to the anthranilate synthase component I family. {ECO:0000305}. |
Annotations taken from UniProtKB at the EBI.