No abstract

The mutant strain Aerobacter aerogenes 62-1 AC, pab-, accumulates a labile substance, desig­nated Compound A which supports the growth of other pab- mutants. Previous studies seemed to indicate that Compound A might be an intermediate in the conversion of chorismate to 4-amino-benzoate (Altendorf, Bacher, and Lingens, Z. Naturforsch. 24 b, 1602 [1969]). The present experi­ ments show that Compound A is 4 -(D-glucosylamino)-benzoic acid. This substance which is clearly not an intermediate in the biosynthesis of 4-aminobenzoate is formed by reaction of 4-aminobenzoate produced de novo by the mutant with exogenous glucose. Mutant 62-1 AC has the unimpaired capacity to synthesize 4-aminobenzoate as shown by direct enzyme studies. Mutant 62-1 AC re­ quires approximately 200 times more 4jaminobenzoate for growth than other pab" mutants of A. aerogenes with defective 4-aminobenzoate synthetase. The genetic defect of mutant 62-1 AC seems to be located in a metabolic system concerned with the utilization of 4-aminobenzoate rather than its synthesis.