A study of the relationship of structure and activity of antimycin A in the induction of carotenoid synthesis in Mycobacterium marinum.

Mycobacterium marinum produces carotenoids when exposed to light or when antimycin A is added. Structural characteristics of antiiycin A in relationship to its induction of carotenoid synthesis were determined in order to make comparisons with the characteristics required for its inhibition of the electron transport system. All four components of the antimycin A complex (AI, Az, AZ, and A4) were equally active. Studies with a number of derivatives and synthetic analogues showed that the substituted dilactone ring and the phenolic hydroxyl group, but not the N-formyl (or an Ncarbonyl) group, are indispensable for the induction activity of antimycin A. Since the N-formyl group (together with the phenolic hydroxyl group and the dilactone ring) is required for the inhibitory activity of antimycin A in the electron transport system, the possibility that antimycin A induces carotenogenesis by interfering in the electron transport system was, therefore, discounted. Additional evidence for the lack of involvement of the electron transport system in the induction of carotenogenesis was provided when it was found that the replacement of the dilactone ring with a long alkyl chain resulted in the total loss of induction activity but not of inhibitory activity. A hypothesis that antimycin A and light induce carotenogenesis by inducing protein synthesis has been evaluated.