L-ALPHA,GAMMA-DIAMINOBUTYRATE-ACTIVATING ENZYME FROM BACILLUS POLYMYXA - PROPERTIES AND DISTRIBUTION

1. 1. An enzyme which catalyses the l-α,γ-diaminobutyrate-dependent exchange of ATP with PPi was partially purified from sonic extracts of the polymyxin B-producing organism, Bacillus polymyxa 2459. This enzyme could be separated from most other amino acid-activating enzymes and exhibited an apparent Km for l-α,γ-diaminobutyrate of 0.6 mM. 2. 2. Treatment of sonic extracts with streptomycin sulfate led to an alteration in the properties of the activating enzyme. This appeared to be due to the conversion of the enzyme from polydisperse aggregates of average molecular weight 300 000 to units of 100 000 molecular weight. 3. 3. In lysed protoplast preparations, the l-α,γ-diaminobutyrate-activating enzyme was predominantly associated with the particulate fraction, in contrast with other amino acid-activating enzymes. The Km for l-α,γ-diaminobutyrate of the particulate preparation was the same as that of the soluble enzyme. 4. 4. The specific activity of the l-α,γ-diaminobutyrate-activating enzyme rose about 10-fold during vegetative growth, beginning at the time of the first appearance of polymyxin in the growth medium. 5. 5. Mutants of B. polymyxa that had lost the ability to produce polymyxin also lacked the l-α,γ-diaminobutyrate-activating enzyme. On the other hand, other polymyxin-producing organisms, such as B. polymyxa ATCC 10401 and B. circulans ATCC 14040, were found to have significant levels of this enzyme. These observations suggest that the l-α,γ-diaminobutyrate-activating enzyme plays a role in the biosynthesis of polymyxin. © 1969.