engleski

Complex regulatory network controls chromosome segregation in streptomycetes

Backgrounds Streptomyces species are multicellular filamentous Actinobacteria, producers of numerous secondary metabolites used in biotechnology and medicine. Streptomycetes undergo complex cellular differentiation including formation of vegetative mycelium followed by aerial mycelium and then spores. The spores are produced at the tip of aerial filaments and help these multicellular bacteria to disperse in the environment. These processes require a complex gene regulatory network of proteins ensuring the proper chromosome organization and partitioning of DNA into pre- spore compartments before septa closure. Various proteins are known to be involved in chromosomal segregation during sporulation and some of them were used in this study. Objectives Our goal was (I) to construct double and triple mutants of ssbB, parB and smc, (II) to examine how these mutations affect chromosome segregation during sporulation in order to elucidate whether these genes participate in the same or various regulatory cascades. Methods PCR targeting system and conjugation were used to construct various strains mutated in selected genes. These strains were examined for growth and sporulation defects. Fluorescence microscopy was used to determine the efficiency of DNA distribution in spores compartments, spore size as well as the number of spores in areal hyphae. Conclusions The results revealed a severe chromosome segregation defect in SsbB depleted S. coelicolor mutant, indicating the importance of SsbB protein for the reproductive stage of growth. In double and triple mutants more pronounced defects in chromosome segregation during sporulation occured than previously reported for any of the parental strains indicating that analysed genes participate in different regulatory network.

Streptomyces coelicolor ; SsbB protein ; chromosome segregation ; sporulation

nije evidentirano