Technical Information on C43(DE3) C41(DE3)

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Frequently Asked Questions
C41(DE3) and C43(DE3) Strains
	01. What is the advantage of using C41(DE3) and C43(DE3) strains? 02. What is the genotype of C41(DE3) and C43(DE3)? 03. Is there any intrinsic antibiotic resistance of OverExpress^TM strains? 04. Do these strains express T7 RNA polymerase? 05. Are there specific tips for handling these strains for optimal results?

C41(DE3) and C43(DE3) Strains
	01.What is the advantage of using C41(DE3) and C43(DE3) strains? These strains are effective in overexpressing toxic proteins from all classes of organisms, eubacteria, archaea, yeast, plant, mammals (see examples in Literature).
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	02.What is the genotype of C41(DE3) and C43(DE3)?? The strain C41(DE3) was derived from BL21(DE3) [E. coli F^- ompT hsdS_B (r_B^- m_B^-) gal dcm (DE3)] as described in Miroux and Walker, 1996. This strain has at least one uncharacterized mutation, which prevents the cell death associated with the expression of toxic recombinant proteins. The strain C43(DE3) was further derived from C41(DE3) transformed with the F-ATPase subunit gene and cured, therefore it contains no plasmid (Miroux and Walker, 1996).
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	03. Is there any intrinsic antibiotic resistance of OverExpress^TM strains? There are no intrinsic antibiotic resistances (or plasmids) in either C41(DE3) or C43(DE3), and it should grow on LB or minimal-glucose media.
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	04. Do these strains express T7 RNA polymerase? Like the parental BL21(DE3) strain constructed at Brookhaven Laboratories (Studier and Moffatt, 1986), C41(DE3) and C43(DE3) carry the lambda DE3 lysogen which expresses T7 RNA polymerase from the lacUV5 promoter by IPTG induction.
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	05.Are there specific tips for handling these strains for optimal results? Protocols for OverExpress^TM strains utilization are available providing details on strains transformation.
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