[Comparative biochemical study of 2 natural inactive variants of the actinomycin C producer Actinomyces sp. 26-115 with varying sensitivity to actinomycin]

Abstract

Two natural variants of the actinomycin C-producing organism Actinomyces sp-26-115, i.e. H1 and H2 differ in their sensitivity to exogenic actinomycin, colony morphology, growth dynamics on the synthetic medium and stability to ultrasound and lysozyme. Both variants synthesize no actinomycin. Variant H1 is sensitive to exogenic actinomycin, while variant H2 is resistant to it. Variants H1 and H2 have some similarity in the composition of membrane proteins. Still, they differ in the protein molecular masses, which are equal to 600000--500000, 220000, 130000. The active variant A and nonactive variant H2 have the most similar compositions of membrane proteins. These variants are also close in their growth dynamics, colony morphology, sensitivity to ultrasound and lysozyme. The membranes of all the variants studied contain phosphatidyl ethanol amide as the main phospholipid component. Insignificant differences are observed only with respect to the minor components. The content of teichoic acids in the cell walls of variant H2 is very high, slightly changes during the developmental stage and insignificantly increases on addition of actinomycin to the medium. The cell wall of variant H1 contains less amounts of teichoic acids. During the developmental stage they are liberated from the wall at a higher rate than peptidoglycan. The sensitivity to actinomycin does not increase with an increase in the culture age. It is probable that teichoic acid of the cell wall is one of the factors providing resistance to actinomycin in variant H2. It may be considered as a barrier preventing transport of exogenic actinomycin into the cell.