OptimizedforcloningtoxicorunstableDNA
StABIlizetoxicinsertsincommoncloningandexpressionvectors(pUCandpET-typevectors)- Cloneandmaintainchallengingsequencesatreducedplasmidcopynumber,theninducetohighcopynumberforDNArecovery
- AvoidT1andT5phagecontaminationwithtonAmutation
- Choosechemicallycompetentcellsforgeneralcloningorelectrocompetentcellsfordemandingapplicationssuchaslibrarygeneration
Applications
- CloningofunstableDNAsequencesorthoseexpressingtoxicproteins.
CopyCutter™EPI400™E.coli*cellsweredevelopedtosignificantlylowerthecopynumberofawidevarietyofcommonvectorssothatyoucanmorereADIlycloneunstableDNAsequences.DNAthatisunstableathigh-copynumberoftencodesforaproteinthatinhibitscellgrowthorcontainsAT-andGC-richsequencesorsequenceswithstrongsecondarystructure(Fig.2).1
TheCopyCutterEPI400celllinewasderivedfromEpicentre'shigh-transformationefficiencyphageT1-resistantTransforMAX™EC100™-T1RE.colistrainbymanipulatingagenethatcontrolsthecopynumberofvectorscontainingColE1orpMB1originsofreplication(e.g.,pUC-andpET-typevectors).Thisconstitutivelyexpressedgene,pcnB(plasmidcopynumber),wasdeletedfromtheTransforMAXEC100strainandreplacedwithamodifiedpcnBgenethatislinkedtoaninducIBLepromoter,creatingtheCopyCutterEPI400strain.
ThecopynumberofColE1-typevectorsintheCopyCutterEPI400straincomparedtotheparentalTransforMAXEC100strainisapproximately4-to25-foldlower,dependingonthevector.Moreover,ashortincubationinthepresenceoftheCopyCutterInductionSolutioncanincreasethecopynumberofthevectortoimproveplasmidyields(Fig.3).
Figure1.Copy-numberofColE1-typeplasmidsisloweredupto25-foldinCopyCutter™EPI400™E.colicells.LanesC,TransforMax™EC100™cells;LanesUandI,uninducedorinducedCopyCutterEPI400cells.DNAextractsfromthesamenumberoflysedcells(basedonOD600)wereloadedperlane.
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| Figure2.DNAinsertsencodingtoxicgeneproductsweresuccessfullyclonedintohigh-copy-numbervectorsusingCopyCutter™EPI400™E.colicells.Aftersequencing,thefull-lengthacpPclonesinTransforMAX™EC100™cellswerefoundtocontainmultiplepointmutations. | Figure3.UninducedCopyCutter™EPI400™E.colicellscontainingaregBclone(laneU)areinducedtohigher-copynumber(laneI)usingtheCopyCutterInductionSolution.CrudeextractsofplasmidDNAwerepreparedfromcellsgrowninselectivemediaandanalyzedbyagarosegelelectrophoresis.Approximatelythesamenumberoflysedcells(basedonA600)wereloadedperlane. |
Benefits
- Maintainclonesatlow-copynumber,theninducetohighercopynumberforimprovedplasmidyield.
- Hightransformationefficiencywithclonesofallsizes.
- tonAforresistancetobacteriophagesT1andT5.
- lacZΔM15forblue/whitescreeningofrecombinants.
- Restrictionminus[mcrA,Δ(mrr-hsdRMS-mcrBC)]genotypeenablesefficientcloningofmethylatedDNA.
- Endonucleaseminus(endA1)toensurehighyieldsofDNA.
- Recombinationminus(recA1)forgreaterstabilityoflargeclonedinserts.
Genotype
F-mcrAΔ(mrr-hsdRMS-mcrBC)Φ80dlacZΔM15ΔlacX74recA1endA1araD139Δ(ara,leu)7697galUgalKλ-rpsL(StrR)nupGtrfAtonApcnB4dhfr
CopyCutterEPI400ElectrocompetentE.coli
- Transformationefficiencyof>1x1010cfu/µgofpUC19.
CopyCutterEPI400ChemicallyCompetentE.coli
- Transformationefficiencyof>1x107cfu/µgofpUC19.
Reference
- Haskins,D.(2004)EpicentreForum11(5),6.
*Coveredbyissuedand/orpendingpatents.
