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HomeProtein ExpressionCompetent Cell Selection & E. coli Markers Guide

Competent Cell Selection & E. coli Markers Guide

We offer a range of Escherichia coli bacterial cells made competent with the highest efficiencies by optimized procedure specific to each strain. Choose from 24 new competent cells for a wide variety of applications, including protein expression, routine or difficult cloning, and library generation. Many trial sizes are available.

ApplicationProduct No.Product DescriptionTransformation EfficiencyGenotypeBlue White Screening Capable
for protein expression and DNA plasmid productionCMC0001SIG10 Chemically Competent Cells≥ 1 × 108F- mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara,leu)7697 galU galK rpsL nupG λ- tonAY
for protein expression and DNA plasmid productionCMC0002SIG10 F' Chemically Competent Cells≥ 5 × 108[F´ pro A+B+ lacIqZΔM15::Tn10 (TetR)] /mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara, leu)7697 galU galK rpsL nupGλ tonAY
for protein expression and DNA plasmid productionCMC0003SIG10 HIGH Electrocompetent Cells≥ 5 × 109F- mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara,leu)7697galU galK rpsL nupG λ- tonA (StrR)Y
for protein expression and DNA plasmid productionCMC0004SIG10 MAX Electrocompetent Cells≥ 2 × 1010F- mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara,leu)7697galU galK rpsL nupG λ- tonA (StrR) Y
for general cloning & library productionCMC0005SIG10 F' MAX Electrocompetent Cells≥ 2 × 1010[F´ pro A+B+ lacIqZΔM15::Tn10 (TetR)] /mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara, leu)7697 galU galK rpsL nupG λ- tonA (StrR) Y
for general cloning & library productionCMC0006SIG10 ULTRA Electrocompetent Cells≥ 4 × 1010F- mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara,leu)7697galU galK rpsL nupG λ- tonA (StrR) Y
for general cloning & library productionCMC0007SIG10 5a Chemically Competent Cells≥ 1 × 108fhuA2Δ(argF-lacZ)U169 phoA glnV44 Φ80 Δ(lacZ)M15 gyrA96 recA1 relA1 endA1 thi-1 hsdR17Y
for plasmid production using unstable DNACMC0008STEADY Chemically Competent Cells> 1 × 107recA13 supE44 ara-14 galK2 lacY1 proA2 rpsL20(StrR) xyl-5 λ– leu mtl-1 F– mcrB mrr hsdS20(rB–, mB–)N
for plasmid production using unstable DNACMC0009STEADY Electrocompetent Cells> 1 × 107recA13 supE44 ara-14 galK2 lacY1 proA2 rpsL20(StrR) xyl-5 λ– leu mtl-1 F– mcrB mrr hsdS20(rB–, mB–)N
for making Uracil-containing DNA for mutagenesisCMC0010CHANGER Electrocompetent Cells1 × 109[F’ Tra+ Pil+ (CamR)] ung-1 relA1 dut-1 thi-1 spoT1 mcrAN
for BAC & cosmid cloningCMC0011XLDNA V2 Electrocompetent cells≥ 1 × 1010F- mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara,leu)7697 galUgalK rpsL nupG (attL araC-PBAD-trfA250 bla attR) λ-Y
for BAC & cosmid cloningCMC0012XLDNA SIG10 Electrocompetent cells≥ 1 × 1010F - pro A+B+ lacIqZΔM15::Tn10 (TetR)] /mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 Φ80dlacZΔM15 ΔlacX74 araD139 Δ(ara, leu)7697 galU galK rpsL nupG λ- tonA (StrR)N
for production of biotinylated proteinsCMC0013BIOTINYLATER F' Electrocompetent Cells>1 ×1010MC1061 [F´ pro A+B+ lacIqZΔM15::Tn10 (TetR)] araD139 ∆(ara-leu)7696 ∆(lac)l74 galU galK hsdR2(rΚ- mΚ+) mcrB1 rpsL (StrR) birAN
for protein expressionCMC0014BL21(DE3) Chemically Competent Cells≥ 1 × 107F – ompT hsdSB (rB- mB-) gal dcm (DE3)N
for protein expressionCMC0015BL21(DE3) pLysE Chemically Competent Cells≥ 1 × 107F – ompT hsdSB (rB- mB-) gal dcm (DE3)N
for protein expressionCMC0016BL21(DE3) Electrocompetent Cells≥ 5 x 109F – ompT hsdSB (rB- mB-) gal dcm (DE3)N
for the highest protein expressionCMC0017OverExpress C41(DE3) Chemically Competent Cells≥ 1 × 106F – ompT hsdSB (rB- mB-) gal dcm (DE3) N
for the highest protein expressionCMC0018OverExpress C41(DE3) pLysS Chemically Competent Cells≥ 1 × 106F – ompT hsdSB (rB- mB-) gal dcm (DE3) pLysS (CmR)N
for the highest protein expressionCMC0019OverExpress C43(DE3) Chemically Competent Cells≥ 1 × 106F – ompT hsdSB (rB- mB-) gal dcm (DE3)N
for the highest protein expressionCMC0020OverExpress C43(DE3) pLysS Chemically Competent Cells≥ 1 × 106F – ompT hsdSB (rB- mB-) gal dcm (DE3) pLysS (CmR)N
for the highest protein expressionCMC0021OverExpress C41(DE3) Electrocompetent Cells≥ 1 × 109F – ompT hsdSB (rB- mB-) gal dcm (DE3)N
for the highest protein expressionCMC0022OverExpress C43(DE3) Electrocompetent Cells≥ 1 × 109F – ompT hsdSB (rB- mB-) gal dcm (DE3)N
for controlled protein expressionCMC0023CONTROLLER SIG10 Chemically Competent Cells> 1 × 109mcrA Δ(mrr-hsdRMS-mcrBC) endA1 recA1 ɸ80dlacZΔM15 ΔlacX74 araD139 Δ (ara,leu)7697 galU galK rpsL (StrR) nupG λ− tonA Mini-F lacIq1 (GentR)N
for controlled protein expressionCMC0024CONTROLLER BL21(DE3) Chemically Competent Cells> 1 × 107F- ompT hsdSB (rB- mB-) gal dcm (DE3) Mini-F lacIq1(GentR)N
Table 1.Competent Cells

E. coli marker
Description
damMethylates A of GATC sites. The dam methyl pattern is used to distinguish old (methylated) from new (unmethylated) strands for damage-repair purposes (repair the unmethylated strand). Dam methylation is also used to time replication (don’t replicate until both strands are dam methylated). This methylation interferes with several restriction enzymes, including BclI and ClaI.
dcmMethylates CCWGG.
dnaJChaperonin. Mutants can stabilize some proteins in E. coli.
dutdUTPase, an enzyme that prevents the incorporation of uracil into DNA by destroying dUTP. Dut-ung double mutants accumulate a significant amount of uracil in their DNA.
e14A prophage-like element, present in K-12 but missing from many derivatives. e14 carries the mcrA gene, so e14- strains are McrA-.
endAThe gene for the end1 nuclease, the primary endonuclease of E coli.
FA self-transmissible plasmid (100 kb) that confers the ability to make pili (i.e. be "male") and thus to be infected by male-specific phage like M13.
F'An F plasmid that picked up some chromosomal DNA from E. coli. The F’ can have its own genotype. Two popular models code for the lacβ peptide (ΔM15), or LacIQ.
hsdRSMRestriction system that methylates host DNA in specific sequences and cleaves DNA that is not as methylated. The R gene is the endonuclease, the M gene is the methylase, and the S gene is required for each to function. Thus hsdR mutants don’t have the endonuclease function, but still methylate. HsdS mutants do not have the endonuclease or the methylase. Two popular models are the K system of E. coli K, and the B system of E. coli B.
lacIQOverproduces the lacI gene product, a repressor of the lac operon.
lacYLactose permease. LacY mutants cannot be used in blue/white screening, but are used to regulate gene expression in IPTG-induced gene expression.
lacZβ-galactosidase gene. The Δ(lacZ)M15 mutation expresses the β fragment. This is commonly found on F’ elements or in a defective 80 φ prophage. Many plasmids express the α fragment. The two together form a functional β-galactosidase.
ΔlacThere are three common deletions involving the entire lacZYA operon in addition to some flanking DNA: ΔU169, Δ X111, and ΔX74.
IonA protease responsible for degrading aberrant proteins and for turning off sulA function. E. coli B naturally lacks lon.
mal BThe malB region encompasses the genes malEFG and malK lamB malM. Δ (malB) deletes most or all of this entire region. LamB is the receptor for lambda phage.
mcr ARestricts DNA with methylcyctosine in certain sequences. McrA is lost when prophage e14 is lost.
mcr BCA system that restricts DNA containing methylcytosine in certain sequences. Δ(mcrC-mrr) deletes six genes: mcrC-mcrB-hsdS-hsdM-hsdR-mrr
mrrA methylcytosine and methyladenine restriction system.
recARequired for most homologous recombination pathways.
recBRequired for ExoV function. Recombination deficient.
recCRequired for ExoV function.
recDRequired for ExoV function. RecD mutants stabilize inverted repeats, but interfere with plasmid maintenance.
recFRecombination gene required for interplasmid homologous recombination.
recJRecombination gene required for interplasmid homologous recombination.
rpoH(or htpR heat shock transcription factor) Required to express some heat shock proteases.
sbcBRequired for Exonuclease I function. Strains carrying recB recC and sbcB are usually also sbcC. These quadruple mutant strains are recombination-proficient and propagate inverted repeats in λ, but plasmid replication is aberrant.
sbcCHelps (with sbcB) to supress the effect of a recBC mutant. sbcC mutants are Rec+ and stably propagate inverted repeats in plasmids.
supE(or glnV) Mutant tRNA inserts glutamine at UAG codons, suppressing UAG mutations in the reading frame. SupE is required for the lytic growth of some phage mutants.
supF(or tyrT) Mutant tRNA inserts tyrosine at UAG codons, thus suppressing the effect of UAG mutations in reading frames. This mutation is required for the lytic growth of some λ phage, such as λgt11.
traDConjugation defective mutant of the F plasmid.
ungMutant in uracil N-glycosylase, an enzyme that removes uracil from DNA. An ung mutant allows uracil to persist in DNA.
φ80dlacΔM15Lysogenic for a defective prophage derivative of φ80. The lacZ ΔM15 allele supplies the beta peptide for blue white screening.
Table 2.Guide to E. coli Markers
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