BL21(DE3)plysS菌株

BL21 strains are the most widely used hosts for protein expression from pET recombinants and have the advantage of being deficient in both lon and ompT proteases. 
DE3 indicates that the host is a lysogen of λDE3, and therefore carries a chromosomal copy of the T7 RNA polymerase gene under control of the lacUV5 promoter. Such strains are suitable for production of protein from target genes cloned in pET vectors by induction with IPTG. 
pLysS strains express T7 lysozyme, which further suppresses basal expression of T7 RNA polymerase prior to induction, thus stabilizing pET recombinants encoding target proteins that affect cell growth and viability. 

Genotype: F^- ompT hsdS_B(r_B^- m_B^-) gal dcm (DE3) pLysS (Cam^R)

BL21(DE3)plysS作为E.coli B宿主菌，主要用来进行蛋白表达，细胞内缺少lon蛋白酶和ompT外膜蛋白酶，能够有效避免目的蛋白的降解。 

BL21(DE3)pLySs来源于BL21(DE3)。DE3是溶源性的λDE3, 所以带有T7 RNA聚合酶的染色体拷贝。该菌株适用于pET系列载体，及其他T7启动子系列载体。能够利用IPTG直接进行蛋白的诱导表达。 

含有pLSs质粒，pLySs质粒能够产生T7溶菌酶，可以有效降低目的基因的基础表达水平。pLySs质粒使得该菌株具有氯霉素抗性。pLySs质粒的起始复制位点是p15 Origin, 这使得该质粒能够和pUC-及pBR322-衍生的质粒互相共存。

BL21(DE3)plysS大肠杆菌菌株产品说明书.pdf