High production of a class III lantipeptide AmfS in <i>Streptomyces griseus</i>

AmfS, a class III lantipeptide serves as a morphogen in <i>Streptomyces griseus</i>. Here, we constructed a high production system of AmfS in <i>S. griseus</i>. We isolated <i>S. griseus</i> Grd1 strain defective in glucose repression of aerial mycelium formation and found it suitable for the overproduction of AmfS. Two expression vectors carrying the strong and constitutive <i>ermE2</i> promoter were constructed using a multicopy number plasmid, pIJ702. The use of the Grd1 strain combined with the expression vectors enabled high production of AmfS by <i>S. griseus</i> into its culture broth. The expression system was also effective for the generation of abundant AmfS derived from <i>Streptomyces avermitilis</i>. In addition, site-directed mutagenesis revealed the amino acid residues essential for the morphogen activity of AmfS. These results indicate that the constructed system enables efficient production of class III lantipeptides by <i>Streptomyces</i>. High production of a class III lantipeptide AmfS in <i>Streptomyces griseus</i>.