What are DE3 cells?
Thermo Scientific BL21(DE3) Competent Cells are suitable for the expression of non-toxic heterologous genes. The strain contains the lambda DE3 prophage that carries the gene for T7 RNA polymerase under control of a lacUV5 promoter, allowing expression of the T7 RNA polymerase to be induced with IPTG.
What is a DE3 E. coli host?
Escherichia coli is one of the most widely used hosts for recombinant protein production in academia and industry. Strain BL21(DE3) is frequently employed due to its advantageous feature of lacking proteases which avoids degradation of target protein.
What is DE3?
The DE3 designation means that respective strains contain the λDE3 lysogen that carries the gene for T7 RNA polymerase under control of the lacUV5 promoter. IPTG is required to maximally induce expression of the T7 RNA polymerase in order to express recombinant genes cloned downstream of a T7 promoter.
What is pLysS?
pLysS is a plasmid that contains the T7 lysozyme gene (LysS). The T7 lysozyme binds to T7 RNA polymerase causing inhibition until induction by the addition of IPTG. When IPTG is added, the amount of T7 RNA polymerase increases and over- comes the inhibition by LysS.
What is the difference between dh5alpha and BL21?
The key difference between BL21 and DH5 Alpha is that BL21 is a protease deficient genetically engineered competent E. coli cell used primarily for protein expression, while DH5 Alpha is a genetically engineered competent E. coli cell with recA1 mutation used primarily for plasmid transformation.
Can I extract plasmid from BL21 cells?
BL21 cells are not designed for plasmid purification but protein expression. BL21 lacks in some proteases but has the endonucleases present. You can make mini-preps and try to isolate the plasmid, but there is a risk that your plasmid may be digested.
Why is E. coli used for protein production?
coli strain (K strain), E. coli BL21 (B strain) is the most used for recombinant protein production because B strains lack some proteases, achieve higher biomass yields and produces much less acetate than E.
What is Iptg used for?
Thermo Scientific IPTG (isopropyl-beta-D-thiogalactopyranoside) is a highly stable synthetic analog of lactose. It inactivates the lac repressor and induces synthesis of beta-galactosidase, an enzyme that promotes lactose utilization. IPTG is used to induce expression of cloned genes under control of the lac operon.
What is so special about Escherichia coli BL21 DE3 and BL21?
Escherichia coli BL21 and BL21(DE3), created by F. E. coli BL21(DE3), a derivative of BL21, is probably the most widely used in high-level expression of recombinant proteins, and it harbors a prophage DE3 derived from a bacteriophage λ, which carries the T7 RNA polymerase gene under the control of the lacUV5 promoter.
What is Lambda DE3 Lysogen?
lambda DE3 is a phage construct that expresses T7 RNA polymerase under the control of a lacUV5 promoter. Lysogens of DE3 are made using a helper phage of heterologous immunity. The int mutation should also prevent normal excision from lysogens.
Why is DH5alpha used?
MAX Efficiency DH5α Competent Cells are a well-known, versatile strain that can be used in many everyday cloning applications. In addition to supporting blue/white screening, recA1 and endA1 mutations in DH5α cells increase insert stability and improve the quality of plasmid DNA prepared from minipreps.