Thelibraryisdistributedas18individualpoolsintheformofDNA.Youwillbesentaboutamicrogramofeach.TransformasuitableamountintoE.coli(useanykanamycin-andtetracycline-sensitivestrainsuitableformakingplasmidpreps).Selecttransformantswith40ug/mlkanamycinand/or3ug/mltetracycline(allowatleastanhourforexpressionfollowingtransformation).Obtain50,000coloniesforeachpool.ElutecoloniesfromplatesinLB;makea-70oCstockofthiseluate.DiluteeluateintoLBplusantibiotictogiveaculturewithanalmostsaturateddensity.Growat37oCforafewhours.MakeminiprepormidiprepDNA. OVERVIEW:MutagenizedDNAfromthelibraryisexcisedfromthebacterialvector.Itisthentransformedintoaura3strainofyeast.Thisprocedureisoutlinedinthisfigure.Thebeststrategyistoscreenafewthousandtransformantsfromeachpool.Useofacircle-zerostrainwillpreventrecoveryofinsertionsinthe2-micronplasmid.Screening30,000transformantsshouldgiveyou95%coverageoftheyeastgenome. Tominimizedoubleintegrants,transformationsshouldcontainthelowestamountofDNApracticable.Wethereforerecommendthatapilotexperimentbeperformedtodeterminetransformationefficiencyofthestrain,andconditionsthenbescaledupasappropriate.ThepilotprotocolgivenbelowusesamodifiedversionofthemethodofChenetal.(1992)..Youshouldusewhatevertransformationprotocolworksbestinyourhands. WehavenotdoneassaysofGFPactivityinyeast. SeeNiedenthaletal(1996)fortheirmethods. WetestedmTn-3xHA/GFPbymutagenesisofBDF1,whichencodesachromatin-associatedprotein.Wegrewindividualbdf1::mTn-3xHA/GFPtransformantstoadensityof107cells/mlinSC-ura.Thelastfourhoursofgrowthwereatroomtemperature,toallowformationoftheGFPchromophore.ThenweexaminedcellsdirectlyusingaLeitzmicroscopywithasystem13filter(thismaynotbeoptimal).In4of38transformants,wesawgreenfluorescenceofthenucleus.Fixationandspheroplastingofthecellsimprovedthesignal-to-noiseratio. Todeterminethesiteoftransposoninsertion,genomicDNAimediatelyadjacenttothetransposonsequencesmustberescued.WehavenotyetconstructedarescuevectorformTn-3XHA/GFP.Ifdemandforthelibraryishighwewillconstructone.Otherwise,wewillbehappytoprovidereagentsandinformationtoanotherlaboratorywhowishestoconstructit.InversePCRongenomicDNAcouldbeusedtorecoverthesiteofinsertion.Alternatively,CarlFriddlehasdevelopeda"vectorettePCR"rescueprotocolforlacZ-basedtransposons.IhavetranscribedCarl"sprotocolandmodifiedthesuggestedenzymesandprimers,tomakeitsuitableforvectorettePCRofthemTn-3xHA-basedtransposons. Whentransposoninsertionhascreatedanin-framefusiontoGFPinthegeneofinterest,thetransposoncanbeexcizedtoleavea274bpinsertion(sequencegivenbelow)containingthe3xHAtag.Withthe5basepairduplicationcausedbytransposoninsertion,thisgivesanin-frame93-aminoacidinsertionintheprotein.ThepopouteventismediatedbycrerecombinaseandrequiresinductionoftheGAL1-10promoterongalactose.Ourstrainsgrowpoorlyongalactosebutgive80to100%popouts. TheHAtripletagcanbedetectedbymousemonoclonalantibodies12CA5(Boehringer)orMMS101R(BAbCo,Richmond,California).Theseantibodyrecognisecross-reactingyeastproteinsofabout55kDor110kD,respectively,andcangiveaspottybackgroundonimmunofluorescence.Despitethisdrawback,the3xHAtaghasbeenusedextensivelyandsuccessfullyinyeast.Arabbitpolyclonalantiseraisalsoavailable(101c500;BabCo)butthiswaslessreactiveintheoneinstancewetried.Protocolsforyeastimmunofluorescencecanbefoundhere,orinMethodsinEnzymology194(1991). N.B.Whentaggingessentialgenes,theoriginalstraintransformedshouldobviouslybediploid.Youcandissectthepopped-outversiontoseeifthetaggedgeneisfunctional.Onlybelieveatagislethalifitiscomplementedbythewild-typegene,andifseveralpopouteventsgivethesamephenotype. TRinuppercase.loxRinbold. GGGGTCTGACGCTCAGTGGAACGAAAACTCACGTTAAGgcggccattgaaggtagaagagaaAATttgtacttccaaagaaagaaggccgctatcgcttcggataactcctgctatacgaagttatgggcggccgtttacccatacgatgttcctgactatgcgggctatccctatgacgtcccggactatgcaggATCCtatccatatgacgttccagattacgctccggccgcCCTTAACGTGAGTTTTCGTTCCACTGAGCGTCAGACCCCMakinglibraryDNAfromtheDNAwesendyou
TransformingyeastwithDNAfromtheinsertionlibrary
ScreeningforGFPfusions
Screeningforin-frameGFPfusionsinyeast
AnalyzingGFPfusionproteinlocalizationinyeast
Identificationofthegenomicsiteoftransposoninsertion
UsingtheHATepitopetaggingfeatureofmTn-3xHA/GFP
SequenceofHATtag(3xHA):
GenBankaccession
Antibioticsused:
Tetracycline,Tet(SigmaT3383) 12mg/mlin50%ethanol.Useat3ug/ml(Tet3) Kanamycin,Kan(SigmaK800) 10mg/mlinwater.Useat40ug/ml(Kan40) Ampicillin,Amp(SigmaA9518) 50mg/mlinwater.Useat50ug/ml(Amp50)