Fig. 1

Diagram of the separate component-stabilization system in Streptomyces. 1. Integration of the toxin (yoeBsl) gene into the chromosome of the S. lividans ∆TA (pGM160-YefMsl^ts) strain [22] with plasmid pTES-Tox. 2. Transformation with pALCre^ts to generate S. lividans ∆TA-pTES-Tox (pGM160-YefMsl^ts, pALCre^ts). 3. Elimination of apramycin resistance gene by induction of Cre recombinase. 4. Transformation with the expression plasmid (pNRoxAnti-Prot) and removal of the temperature-sensitive plasmids. 5. Transformation with pALDre^ts and elimination of the neomycin resistance gene from the expression plasmid (pNRoxAnti-Prot) by Dre recombinase induction. 6. Removal of the temperature-sensitive plasmid pALDre^ts and generation of the final host strain [S. lividans ∆TA -Tox (pRoxAnti-Prot)]. 7. Protein production