Fig. 4.

(A) An overview of four major approaches for transcriptional of BGC expression, including the use of different promoters and terminators, sigma factor engineering and CRISPR interference with a deactivated Cas9 (dCas9). P: promoter; T: terminator; RNAP: RNA polymerase. (B) Selected examples that tuned the expression of cyanobacterial BGCs using promoters or terminators in E. coli or cyanobacterial strains. Pn: native promoter. Dashed arrows and lines indicate additional biosynthetic genes of the BGCs.