Disease relevance of pabA

• Expression of Escherichia coli pabA [1].
• A plasmid library of Acinetobacter calcoaceticus HindIII fragments was constructed, and clones that complemented an Escherichia coli pabA mutant were selected [2].

High impact information on pabA

• The Escherichia coli pabA and pabB genes have been overexpressed separately and in tandem [3].
• We have determined the entire nucleotide sequence of Escherichia coli pabA [4].
• Disruption of the secondary structure by mutation allowed expression of pabA from P2, as did translation of ribosomes into the fic-pabA intergenic region [1].
• The lack of pabA expression from P2 appears to be the result of a stable secondary structure in the intergenic space preceding pabA that sequesters the pabA ribosome binding site [1].
• We have determined the nucleotide sequences of 1,362 base pairs preceding E. coli pabA and of 981 base pairs preceding S. typhimurium pabA [5].

Chemical compound and disease context of pabA

• Escherichia coli p-aminobenzoate synthase is composed of two nonidentical subunits encoded by pabA and pabB and has been assumed to be the sole enzyme responsible for p-aminobenzoate biosynthesis from chorismate and glutamine [6].
• Introducing vectors containing the 3.8 kb NcoI fragment of S. venezuelae DNA into pabA and pabB mutants of Escherichia coli, or into the Streptomyces lividans pab mutant JG10, enhanced sulfanilamide resistance in the host strains [7].

Biological context of pabA

• The fic gene, near pabA located at 75 min of the Escherichia coli chromosome, was previously identified as the regulatory factor of cell division [8].
• A 2.7-kb BamHI-SstI fragment of the cloned DNA complemented pabA and pabB mutations in both E. coli and S. lividans; complementation in S. lividans was accompanied by integration of the recombinant plasmid into the host chromosome [9].

Associations of pabA with chemical compounds

• The gene downstream from fic was found to be pabA (p-aminobenzoate) [10].
• However, expression analysis using chromosomal pabA-lacZ translational fusions indicated that P1 expressed PabA at least 50-fold more efficiently than P2. pabA-dependent growth rate analysis indicates that P1 is essential and P2 is dispensable for PABA metabolism [5].
• Anthranilate synthetase is composed of proteins encoded by the genes trp(G)D and trpE, whereas p-aminobenzoate synthetase is composed of proteins encoded by pabA and pabB [11].

References