A possible role of d-valine and related d-amino acids in repression of enzyme and actinomycin synthesis

Abstract

The addition of D-valine and related D-amino acids to the production medium blocks kynurenine formamidase II and actinomycin D synthesis by Streptomyces parvulus. This effect may be due to a direct inhibition of the actinomycin synthetase-catalyzed racemization of L-valine to its peptide bound D-form during antibiotic formation. In addition, the D-amino acid(s) may influence enzyme and actinomycin synthesis through carbon and/or nitrogen catabolite regulation. The relatively slow uptake and metabolism of the D-amino acid would provide a continuous supply of catabolite(s) that repress transcription of actinomycin biosynthetic genes over a long period of time.