Editing BL21Cells (section)

== BL21 Star (DE3)pLysS ==

F- ompT hsdSB (rB-mB-) gal dcm rne131 (DE3) pLysS (CamR), from Invitrogen, Cat #: C6565-03 

The pLysS plasmid carried by the BL21 StarTM(DE3)pLysS strain produces T7 lysozyme to reduce basal level expression of the gene of interest. pLysS confers resistance to chloramphenicol (CamR) and contains the p15A origin. This origin allows pLysS to be compatible with pUC- or pBR322-derived plasmids. It requires IPTG to induce expression of the T7 RNA polymerase from the lacUV5 promoter. 

RNaseE (rne131), which is one of the major sources of mRNA degradation. BL21 Star cells significantly improve the stability of mRNA transcripts and increase protein expression yield from T7 promoter-based vectors due to rne131 mutation.