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Smartox/Selective blocker of Nav1.5 channel/12JZH003-00100/0.1mg
Jingzhaotoxin-III(ß-TRTX-Cj1α) hasbeenisolatedinitiallyfromtheChineseTarantulaspider ChilobrachysJingzhaovenom. Jingzhaotoxin-III selectivelyinhibitstheactivationofthevoltage-dependentsodiumchannel Nav1.5 inheartorcancercellswithanIC50valuecloseto350nM.ItisinactiveonNav1.2,Nav1.4,Nav1.6andNav1.7andshouldthereforebeconsideredasaninterestingresearchtooltodiscriminatebetweensodiumchannelsubtypes. Jingzhaotoxin-III bindsontoreceptorsite4presumablylocatedonDIIS3-S4linkerof Nav1.5 andsupposedlyblocks Nav1.5 throughadifferentmechanismthan ProTx-II and HuwentoxinIV.ß-TRTX-Cj1αiscomposedof36aminoacidresiduesincluding6cysteinescross-linkedaccordingtoaC1-C4,C2-C5andC3-C6pattern. Jingzhaotoxin-III alsoinhibits Kv2.1channel withanIC50 ofaround700nM.
Fig1: RepresentativeeffectsofdifferentJinghzaotoxinIIIconcentrationsontheamplitudeofINa.JinghzaotoxinIIIwasappliedexternallytothecellatthetimeandconcentrationsindicatedontop. InwardsodiumcurrentsweretriggeredinhumanMDA-MB-231breastcancercellsby30ms-longvoltagestepsfrom-100to-5mV,fromaholdingpotentialof-100mV.1stepevery2sec.
Description:
AAsequence: Asp-Gly-Glu-Cys4-Gly-Gly-Phe-Trp-Trp-Lys-Cys11-Gly-Arg-Gly-Lys-Pro-Pro-Cys18-Cys19-Lys-Gly-Tyr-Ala-Cys24-Ser-Lys-Thr-Trp-Gly-Trp-Cys31-Ala-Val-Glu-Ala-Pro-OH
Disulfidebonds: Cys4-Cys19,Cys11-Cys24,andCys18-Cys31
Length(aa): 36
Formula: C174H241N47O46S6
MolecularWeight: 3919.53Da
Appearance: Whitelyophilizedsolid
Solubility: aqueousbuffer
CASnumber: notavailable
Source: Synthetic
Purityrate:>98%
Reference:
Analysisoftheinteractionoftarantulatoxinjingzhaotoxin-III(β-TRTX-Cj1α)withthevoltagesensorofKv2.1uncoversthemolecularbasisforcross-activitiesonKv2.1andNav1.5channels
Animalvenomscontainafascinatingarrayofdivergentpeptidetoxinsthathavecross-activitiesondifferenttypesofvoltage-gatedionchannels.However,theunderlyingmechanismremainspoorlyunderstood.Jingzhaotoxin-III(JZTX-III),a36-residuepeptidefromthetarantulaChilobrachysjingzhao,isspecificforNav1.5andKv2.1channelsoverthemajorityofotherionchannelsubtypes.JZTX-IIItrapstheNav1.5DIIvoltagesensoratclosedstatebybindingtotheDIIS3-S4linker.Inthisstudy,electrophysiologicalexperimentsshowedthatJZTX-IIIhadnoeffectonfivevoltage-gatedpotassiumchannelsubtypes(Kv1.4,Kv3.1,andKv4.1-4.3),whereasitsignificantlyinhibitedKv2.1withanIC50of0.71±0.01μM.MutagenesisandmodelingdatasuggestedthatJZTX-IIIdocksattheKv2.1voltage-sensorpaddle.AlaninereplacementofPhe274,Lys280,Ser281,Leu283,Gln284,andVal288coulddecreaseJZTX-IIIaffinityby7-,9-,34-,12-,9-,and7-fold,respectively.Amongthem,S281isthemostcrucialdeterminant,andthesubstitutionwithThronlyslightlyreducedtoxinsensitivity.Incontrast,asingleconversionofSer281toAla,Phe,Ile,Val,orGluincreasedtheIC50valueby>34-fold.Alanine-scanningmutagenesisexperimentsindicatedthatthefunctionalsurfaceofJZTX-IIIboundtotheKv2.1channeliscomposedoffourhydrophobicresidues(Trp8,Trp28,Trp30,andVal33)andthreechargedresidues(Arg13,Lys15,andGlu34).ThebioactivesurfacesofJZTX-IIIinteractingwithKv2.1andNav1.5areonlypartiallyoverlapping.Theseresultsstronglysupportedthehypothesisthatanimaltoxinsmightusepartiallyoverlappingbioactivesurfacestotargetthevoltage-sensorpaddlesoftwodifferenttypesofionchannels.Increasingourunderstandingofthemolecularmechanismsoftoxinsinteractingwithvoltage-gatedsodiumandpotassiumchannelsmayprovidenewmolecularinsightsintothedesignofmorepotentionchannelinhibitors.
TaoH., etal. (2013)Analysisoftheinteractionoftarantulatoxinjingzhaotoxin-III(β-TRTX-Cj1α)withthevoltagesensorofKv2.1uncoversthemolecularbasisforcross-activitiesonKv2.1andNav1.5channels.Biochemistry. PMID: 24044413
Molecularbasisofthetarantulatoxinjingzhaotoxin-III(Beta-TRTX-Cj1alpha)interactingwithvoltagesensorsinsodiumchannelsubtypeNav1.5
Withconservedstructuralscaffoldanddivergentelectrophysiologicalfunctions,animaltoxinsareconsideredpowerfultoolsforinvestigatingthebasicstructure-functionrelationshipofvoltage-gatedsodiumchannels.Jingzhaotoxin-III(β-TRTX-Cj1α)isauniquesodiumchannelgatingmodifierfromthetarantulaChilobrachysjingzhao,becausethetoxincanselectivelyinhibittheactivationofcardiacsodiumchannelbutnotneuronalsubtypes.However,themolecularbasisofJZTX-IIIinteractionwithsodiumchannelsremainsunknown.Inthisstudy,weshowedthatJZTX-IIIwasefficientlyexpressedbythesecretorypathwayinyeast.Alanine-scanninganalysisindicatedthat2acidicresidues(Asp1,Glu3)andanexposedhydrophobicpatch,formedby4Trpresidues(residues8,9,28and30),playimportantrolesinthebindingofJZTX-IIItoNav1.5.JZTX-IIIdockedtotheNav1.5DIIS3-S4linker.MutationsS799A,R800A,andL804AcouldadditivelyreducetoxinsensitivityofNav1.5.WealsodemonstratedthattheuniqueArg800,notemerginginothersodiumchannelsubtypes,isresponsIBLeforJZTX-IIIselectivelyinteractingwithNav1.5.ThereversemutationD816RinNav1.7greatlyincreasedthesensitivityoftheneuronalsubtypetoJZTX-III.Conversely,themutationR800DinNav1.5decreasedJZTX-III’sIC₅₀by72-fold.Therefore,ourresultsindicatedthatJZTX-IIIisasite4toxin,butdoesnotpossessthesamecriticalresiduesonsodiumchannelsasothersite4toxins.OurdataalsorevealedtheunderlyingmechanismforJZTX-IIItobehighlyspecificforthecardiacsodiumchannel.
MingqiangRong, etal.(2011)Molecularbasisofthetarantulatoxinjingzhaotoxin-III(Beta-TRTX-Cj1alpha)interactingwithvoltagesensorsinsodiumchannelsubtypeNav1.5. FASEBJ. PMID: 21665957
Jingzhaotoxin-III,aNovelSpiderToxinInhibitingActivationofVoltage-gatedSodiumChannelinRatCardiacMyocytes
Wehaveisolatedacardiotoxin,denotedjingzhaotoxin-III(JZTX-III),fromthevenomoftheChinesespiderChilobrachysjingzhao.Thetoxincontains36residuesstABIlizedbythreeintracellulardisulfidebridges(I-IV,II-V,andIII-VI),assignedbyachemicalstrategyofpartialreductionandsequenceanalysis.Clonedandsequencedusing3′-rapidamplificationofCDNAendsand5′-rapidamplificationofcDNAends,thefull-lengthcDNAencodeda63-residueprecursorofJZTX-III.Differentfromotherspiderpeptides,itcontainsanuncommonendoproteolyticsite(-X-Ser-)anteriortomatureproteinandtheinterveningregionsof5residues,whichisthesmallestinspidertoxincDNAsidentifiedtodate.Underwholecellrecording,JZTX-IIIshowednoeffectsonvoltage-gatedsodiumchannels(VGSCs)orcalciumchannelsindorsalrootganglionneurons,whereasitsignificantlyinhibitedtetrodotoxin-resistantVGSCswithanIC(50)valueof0.38microminratcardiacmyocytes.Differentfromscorpionbeta-toxins,itcauseda10-mVdepolarizingshiftinthechannelactivationthreshold.ThebindingsiteforJZTX-IIIonVGSCsisfurthersuggestedtobesite4withasimplecompetitiveassay,whichat10micromeliminatedtheslowingcurrentsinducedbyButhusmartensiKarschI(BMK-I,scorpionalpha-liketoxin)completely.JZTX-IIIshowshigherselectivityforVGSCisoformsthanotherspidertoxinsaffectingVGSCs,andthetoxinhopefullyrepresentsanimportantligandfordiscriminatingcardiacVGSCsubtype.
YuchengXiao, etal.(2004)Jingzhaotoxin-III,aNovelSpiderToxinInhibitingActivationofVoltage-gatedSodiumChannelinRatCardiacMyocytes. JBC. PMID: 15084603
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