FIGURE 3.

CRISPRa of internal promoters in the epothilone operon. (A) Yields of epothilones A and B and their summation in different activation mutants and M. xanthus ZE9. (B) RT-qPCR analysis of expression levels of the seven operon genes in different mutants and M. xanthus ZE9 after 48 h of incubation. The expressions of the operon genes in M. xanthus ZE9 were each set as 1, and the expressions of the genes in mutant strains are shown as the relative expression. The error bars represent the standard deviation of three independent experiments. For statistical analysis between the ancestral strain and mutant strains, the signals of ** and * mean p < 0.01 and p < 0.05, respectively.