Fig. 2

Rational selection of constitutive promoters in S. coelicolor. a Flow chart of the selection of constitutive promoters. b Transcript levels of genes with stable expression profiles after primary identification (941, black circles) and rational selection (166, blue dots). The red dots indicated genes whose promoters were selected for experiment validation. c The relative strengths of the 166 putative constitutive promoters based on RNA-Seq. The relative strengths of these promoters were reflected by the reads per kilobase per million mapped reads (RPKM) values of their downstream genes. The strength of the promoter of sco0119, which had the lowest RPKM value, was set to one. The red column indicates the experimentally tested constitutive promoters