SUMMARY: A gene () encoding the aminase activity of p-aminobenzoate (PABA) synthase in subsp. was cloned in pIJ41 and expressed in strains defective in PABA biosynthesis. Expression of the gene was associated with a 1.2 kb deletion between the promoter and the cloning site in pIJ41. Subcloning in pBR322 and expression in AB3295 of the cloned DNA fragment localized the -complementing gene in a 1.9 kb segment. The nucleotide sequence of this segment contained a 1410 bp open reading frame encoding a 470-amino-acicl polypeptide of 50937 Da. The deduced amino acid sequence showed substantial similarity to those reported for PabB and TrpE from several organisms. Synonymous codon usage reflected the low G + C content in the genomic DNA of subsp. lactis, and therefore differed markedly from the preferred usage in the host. The cloned heterologous DNA was expressed in amounts that allowed accumulation of excreted PABA in cultures of transformants.


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