Fig. 4: The promoters and the transcription initiation sites of the gene cluster.

a The reverse-transcription PCR results with the 10 pairs of primers to amplify the ten intergenic regions (Fig. 1a) from cDNA of the induced B. licheniformis MW3. b The pBluescript SK- plasmid contained egfp as the reporter gene. A terminator was inserted in the front of the egfp gene to prevent potential transcription of egfp from an upstream promoter. The 10 intergenic regions (IR1-IR10, Fig. 1a) were assembled between the terminator and the egfp gene with no intergenic region group insertion as control. c The fluorescence intensities of the reporter screening system. A promoter-reporter plasmid without any intergenic region was used as the control. E. coli strain MG1655 was used as the host. d The intergenic regions of IR1, IR2, and IR9 were further truncated from 5'-end. The detailed sequence information was shown in Supplementary Fig. 5. The initiation strength of the truncated promoter was assayed with the eGFP system. e The annotated promoters with the transcription initiation sites. When appropriate, three parallel experiments were performed to obtain the averages and standard deviations. Data are presented as mean ± SD. One-way ANOVA was performed to calculate the p-values with the no intergenic region group insertion group as control, and asterisks indicate statistically significant difference (*p < 0.05, **p < 0.01, ***p < 0.001, ns = (p > 0.05)).