[Modulation of serine/threonine protein kinase activity in chloramphenicol-resistant mutants of Streptomyces avermitilis]. / Modulirovanie aktivnosti serin-treonin-proteinkinaz u khloramfenikol-ustoichivykh mutantov Streptomyces avermitilis.

ABSTRACT

A mutation to chloramphenicol resistance (Cmlr) stimulates production of macrolide avermectin in Streptomyces avermitilis; production starts in early stationary growth. By labeling in vivo, the Cmlr mutation was shown to stimulate phosphorylation of Ser and Thr in several proteins in the same growth phase. Autophosphorylation of active protein kinases (PK) was analyzed in gel after one- or two-dimensional PAGE for the original S. avermitilis strain ATCC 31272, its Cmlr mutant, and a Cmls revertant. An increase in in vivo phosphorylation was associated with an increase in autophosphorylation of Ser/Thr-PK 41K, 45K, 52K, 62K, and 85K and complete suppression of autophosphorylation of PK 66K. Comparison of the PK molecular weights and pI with the parameters deduced for putative PK encoded by S. avermitilis genes identified the 41K, 45K, 52K, 62K, and 85K PK as pkn 24, pkn 32, pkn 13, pkn 12, and pkn 5, respectively. Prenylamine lactate, a modulator of calmodulin-dependent processes, substantially reduced the avermectin production, impaired the Cml resistance, and selectively inhibited Ca2+-dependent PK 85K in the Cmlr mutant. It was assumed that PK 85K is involved in regulating the avermectin production.