Horbal L. Actinomycetes genes that control reduction, oxygnation and glycosylation in biosynthesis of angucyclic antibiotics

The research data on the biosynthesis of three angucyclic antibiotics: landomycin Е in S. globisporus 1912, urdamycin А in S. fradiae Tu2717 and simocyclinone D8 in S. antibioticus Tu6040 is covered in this work. The inactivation of oxygenase gene lndE, involved in the biosynthesis of landomycin Е has been carried out and its function has been determined as 12С-oxygenase. The sequence of oxygenation reactions of landomycin Е polyketide precursor has been proposed. Heterologous expression of urdamycin glycosyltransferase gene urdGT2 in lndE-mutant S. globisporus E7 leads to the formation of new glycosylated analogues of prejadomycin. The comparison of landomycin and urdamycin biosynthetic pathways has been performed. Two oxygenase genes urdМ and lanM2 have been heterologously expressed in six angucycline producing strains, which resulted in the production of new polyketide aromatic metabolites. Targeted inactivation of a putative oxygenase gene simA7 in S. antibioticus Tu6040 lead to discontinuance of simocyclinones biosynthesis, which witnesses the role of the gene in scaffold formation. The gene product of simA8 has been clarified to be involved in oxygen atom introduction to the С12b position of simocyclinone precursor. By means of protoplast fusion we carried out breeding of the mutants, obtained after inactivation and heterologous expression of angucycline oxygenase and glycosyltransfe-rase genes. Selected after S. fradiae urdQ/R and S. globisporus M12 protoplast fusion mutant Rec5 produces about 40 compounds of angucyclic nature, among which novel olivosyltetangomycin and three glycosilated derivatives of tetrangulol. The efficacy of Сre-recombination application in tandem with Redirect-technology in introduction of large-scale deletions into the chromosome of S. coelicolor М145 has been approved. The largest two genomic islands (GI2 and GI5) and the left chromosome end have been deleted, which resulted in the genome reduction and its rescue from recombinogenic DNA, in order to apply the strain as a host for heterologous expression of angucycline biosynthetic genes.