- Transformation efficiency: 1–3 x 107 cfu/µg pUC19 DNA
- BL21(DE3) containing the Lemo System™
- Tunable T7 Expression Strain for difficult targets: membrane proteins, toxic proteins and proteins prone to insoluble expression
- Deficient in proteases Lon and OmpT
- Resistant to phage T1 (fhuA2)
- Lemo System™ maintained by chloramphenicol
Lemo21(DE3) offers the host features of BL21(DE3) while also allowing for tunable expression of difficult clones. Tunable expression is achieved by varying the level of lysozyme (lysY), the natural inhibitor of T7 RNA polymerase. The level of lysozyme is modulated by adding L-rhamnose to the expression culture at levels from zero to 2000 µM. When Lemo21(DE3) is grown without rhamnose, the strain performs the same as a pLysS containing strain. However, optional addition of rhamnose tunes the expression of the protein of interest. For difficult soluble proteins, tuning the expression level may also result in more soluble, properly folded protein.
- Tunable T7 expression for difficult targets
GenotypefhuA2 [lon] ompT gal (λ DE3) [dcm] ∆hsdS/ pLemo(CamR)
λ DE3 = λ sBamHIo ∆EcoRI-B int::(lacI::PlacUV5::T7 gene1) i21 ∆nin5
pLemo = pACYC184-PrhaBAD-lysY
The following reagents are supplied with this product:
|Store at (°C)||Concentration|
|L-rhamnose solution||500 mM|
|pUC19 Transformation Control Plasmid||-20||0.05 ng/μl|
Advantages and Features
Properties and Usage
|Antibiotics for Plasmid Selection||Working Concentration|
- Ships on dry ice
Quality Control AssaysThe following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page.
- Transformation Efficiency:
The competent cells are tested for transformation efficiency and pass minimum release criteria. Transformation efficiency is defined as the number of colony forming units (cfu) which would be produced by transforming 1 μg of plasmid into a given volume of competent cells.
Legal and Disclaimers
Research Use Only
- RESEARCH USE ASSURANCE STATEMENT
The buyer and user have a non-exclusive sub-license to use this system or any component thereof for RESEARCH PURPOSES ONLY, based upon agreement to the following assurances:
Transfer of the host cells that contain the cloned copy of the T7 gene 1 to third parties is explicitly prohibited. This information applies to E. coli ER2566, ER2833, ER3011, ER3012, ER3013 and ER3021, SHuffle® T7, SHuffle® T7 LysY, SHuffle® T7 Express, SHuffle® T7 Express LysY and their competent derivatives, C2566, C2833, C3010, C3013, C3016, C3022, C3026, C3027, C3029 and C3030 when povided separately or when provided in combination with appropriate vectors for said systems.
The Lemo System™ (pACYC184-rhaBAD-lysY): This construct is referred to as pLemo in Wagner et al. (2008) Proc. Natl. Sci. USA 105:14371–14376. Tunable T7 expression is achieved by modulating the level of T7 lyosyme (LysY) via L-rhamnose induction of the rhaBAD promoter.
The Lemo System™ is owned by Xbrane Biosciences AB (Stockholm, Sweden) and has been exclusively licensed to New England Biolabs, Inc. for the manufacture and distribution of Lemo21(DE3) Competent E. coli.
The purchase of this product conveys to the non-commercial purchaser the non-transferable right to use the purchased amount of the product and components of the product for research use only conducted by the researcher. For commercial purchasers using this product for research, the purchase of this product conveys to the purchaser the non-transferable right to use the purchased amount of the product and components of the product for a six (6) month evaluation period after the date of purchase for research use only. After the six (6) month evaluation period, continued use of this product for either commercial research or commercial purposes may require a commercial license. For more information, contact New England Biolabs, Inc. at email@example.com. Commercial research and/or commercial purposes means any activity by a party for consideration and may include, but it not limited to: (1) use of the product or its components in manufacturing; (2) use of the product or its components to provide a service, information or data; (3) use of the product or its components for therapeutic, diagnostic or prophylactic purposes; or (4) resale of the product or its components, whether or not such product or its components are resold for use in research. If the Purchaser is unwilling to accept the limitations of the limited-use statement, NEB is willing to accept return of the products with a full refund.
A license to use this system or any components thereof for commercial purposes may be obtained from New England Biolabs, Inc.
Commercial Laboratory Buyer and User:
Use of the host cells ER2566, ER2833, C2566, C2833, C3010, C3013, C3016, C3022, C3026, C3027, C3029, C3030, SHuffle® T7, SHuffle® T7 LysY, SHuffle® T7 Express, SHuffle® T7 Express LysY or their competent derivatives that contain the cloned copy of T7 gene 1, the gene for T7 RNA polymerase for any purpose other than in combination with either a T7/MAL or T7/IMPACT vector is explicitly prohibited.
Use of the host cells that may contain the cloned copy of the T7 gene 1, the gene for T7 RNA polymerase with any other vector(s) containing a T7 promoter to direct the production of RNA or protein requires a license from Brookhaven National Laboratory. Information about research-use or commercial-use license agreement may be obtained from the Office of Intellectual Property and Sponsored Research, Brookhaven Natonal Laboratory, Buildng 475D, P.O. Box 5000, Upton, New York 11973-5000. Tel.: 631-344-7134. Fax: 631-344-3729.
You may refuse this non-exclusive research license agreement by returning the enclosed materials unused. By keeping or using the enclosed materials, you agree to be bound by the terms of this sub-license.
ACADEMIC AND NON-PROFIT LABORATORY ASSURANCE LETTER
The T7 expression system is based on technology developed at Brookhaven National Laboratory under contract with the U.S. Department of Energy and is the subject of patent applications assigned to Brookhaven Science Associates, LLC (BSA). BSA will grant a non-exclusive license for use of this technology, including the enclosed materials, based upon the following assurances:
- These materials are to be used for noncommercial research purposes only. A separate license is required for any commercial use, including the use of these materials for research purposes or production purposes by any commercial entity. Information about commercial licenses may be obtained from the Office of Intellectual Property and Sponsored Research, Brookhaven National Laboratory, Building 475D, P.O. Box 5000, Upton, New York 11973-5000, telephone (631) 344-7134.
- No materials that contain the cloned copy of T7 gene 1, the gene for T7 RNA polymerase, may be distributed further to third parties outside of your laboratory, unless the recipient receives a copy of this license and agrees to be bound by its terms. This limitation applies to strains ER2566, C2566, C3010, C3013, C3016, C3022, BL21(DE3), BL21(DE3)pLysS, and BL21(DE3)pLysE, SHuffle T7, SHuffle T7 LysY, SHuffle T7 Express, SHuffle T7 Express LysY their competent derivatives, and any derivatives you may make of them, including such strains containing recombinant vectors.
Material Safety Datasheets
- CAUTION: This product contains DMSO, a hazardous material. Review the MSDS before handling.
- STORAGE AND HANDLING: Competent cells should be stored at -80°C. Storage at -20°C will result in a significant decrease in transformation efficiency. Cells lose efficiency whenever they are warmed above -80°C, even if they do not thaw.
- Chloramphenicol must be added at 30 μg/ml to maintain the Lemo System™.
- What are the solutions/recipes (C2528)?
- What are the strain properties (C2528)?
- Why are there no colonies or no growth in liquid culture (C2529)?
- Why is induced protein insoluble (C2528)?
- Why is there no protein visible on gel or no activity (C2528)?
- Can I store competent cells at -20°C instead of -80°C?
- Which kind of transformation tubes should be used?
- What volume of DNA can be added into competent cells?
- What is the shelf life for this strain (NEB #C2528H)?
- Are NEB's competent cells compatible with the "Plate and Go" protocol?