FIGURE 6.

Updated mechanism of coelimycin BGC regulation by cluster-situated regulators. Black arrows indicate γ-butyrolactone SCB1 and CPK production. Solid red lines ending with bars indicate inhibition of ScbR by SCB1 and direct repression by promoter binding. Dashed red lines indicate putative negative feedback loop exerted by coelimycin. Blue lines ending with arrows denote transcription activation. Thin blue arrow indicates weak activation of scoT transcription by CpkO independent from CpkN. Dashed lines imply an indirect or unknown regulatory mechanism (unknown binding site of the activator). CPK biosynthetic genes are marked with a yellow background. Regulatory genes are omitted from the cluster scheme for clarity.