Purotoxin-1(PT-1) isapeptideoriginallyisolatedfromtheCentralAsianspiderGeolycosa sp. Purotoxin-1 wasshowntoinhibitselectively P2X3receptorchannels ata100nMconcentration.Studieswerecarried-outonculturedratDRGneurons.Patch-clampexperimentsdidnotshowanyinhibitoryeffectofPT-1onvoltage-gatedchannels(potentialsrangetestedfrom-100to20mV),neitheronTRPV1(afteractivationwith500nMcapsaicin).Theselectivityof Purotoxin-1 forP2X3washighlightedbyactivatingthisreceptorwith10µMATPand100µMα,βMethylene-ATP.Indeed,unlikeP2X3,P2X2andheterodimerP2X2/3areknowntobenotsensitivetosuchconcentrations.Moreover,P2X3,P2X2,andP2X2/3aretheonlyknownATP-sensitivereceptorsexpressedinplasmamembranesofDRGneurons.So,theobservedeffectseemstobewellrelatedtoaselectiveinhibitionofP2X3.P2X3-mediatedcurrentwasfullyinhibitedwith100nMPurotoxin-1,makingitthemostpotentandselectiveligandforP2X3.
P2X3receptorsareknowntobeimplicatedinpainmechanisms.Behavioralexperimentationscarried-outonratpainmodelsusing0.5nmolPT-1injectedintraplantarshowedtoreducenociception.Thisanti-nociceptiveeffectiscomparabletoA-317491compound(Abbott’sdrug)withanamountofalmost3ordersofmagnitudelower.
Description:
AAsequence:Gly-Tyr-Cys3-Ala-Glu-Lys-Gly-Ile-Arg-Cys10-Asp-Asp-Ile-His-Cys15-Cys16-Thr-Gly-Leu-Lys-Cys21-Lys-Cys23-Asn-Ala-Ser-Gly-Tyr-Asn-Cys30-Val-Cys32-Arg-Lys-Lys-NH2
Disulfidebridges: Cys3-Cys16;Cys10-Cys21;Cys15-Cys32;Cys23-Cys30
Length(aa): 35
Formula: C155H248N50O48S8
Molecularweight: 3834.59Da
Appearance: Whitelyophilizedsolid
Solubility: waterandsalinebuffer
CASnumber:
Source: Synthetic
Purityrate: >97%
Reference:
ModulationofP2X3receptorsbyspidertoxins
Recently,thenovelpeptidenamedpurotoxin-1(PT1)hasbeenidentifiedinthevenomofthespiderGeolycosasp.andshowntoexertmarkedmodulatoryeffectsonP2X3receptorsinratsensoryneurons.Herewestudiedanotherpolypeptidefromthesamespidervenom,purotoxin-2(PT2),anddemonstratedthatitalsoaffectedactivityofmammalianP2X3receptors.ThemurineandhumanP2X3receptorswereheterologouslyexpressedincellsoftheCHOline,andnucleotide-gatedcurrentswerestimulatedbyCTPandATP,respectively.BothPT1andPT2negligIBLyaffectedP2X3-mediatedcurrentselicitedbybriefpulsesoftheparticularnucleotide.WhensubthresholdCTPorATPwasaddedtothebathtoexertthehigh-affinitydesensitizationofP2X3receptors,bothspidertoxinsstronglyenhancedthedesensitizingactionoftheambientnucleotides.Attheconcentrationof50nM,PT1andPT2elicited3-4-folddecreaseintheIC(50)doseofambientCTPorATP.Incontrast,100nMPT1andPT2negligiblyaffectednucleotide-gatedcurrentsmediatedbymP2X2receptorsormP2X2/mP2X3heteromers.Altogether,ourdatapointoutthatthePT1andPT2toxinsspecificallytargetthefast-desensitizingP2X3receptor,thusrepresentingauniquetooltomanipulateitsactivity.
PurinergicMembraneReceptorsasTargetsfortheEffectofPurotoxin1,aComponentofVenomofSpidersfromtheGeolycosaGenus
Weexaminedeffectsofpurotoxin1(PT1),acomponentofthevenomof Geolycosa spiders,onafewvoltageandligand-operatedionchannelspresentintheplasmamembraneofsensoryneuronsfromtheratdorsalrootganglia(DRGs).Purotoxin1ina100nMconcentrationevokednochangesinioncurrentsthroughvoltage-operatedsodium,potassium,andcalciumchannelsinthemembranesofisolatedsensoryneurons.Thisagentwasalsofoundtobeineffectivewithrespecttocapsaicin-sensitivereceptor-channelcomplexes(TRPV1).TestingoftheeffectsofPT1onpurinergicreceptor-channelcomplexesP2X3,P2X2,andP2X2/3showedthatthistoxinisahighlyselectiveblockerofexclusivelyP2X3receptors.TheselectivityofactionofPT1demonstratedinourexperimentsshowsthatitisauniqueagent,whichopensupnewProspectsinthestudiesofstructural/functionalpeculiaritiesofreceptor-channelcomplexesP2X3asaperipherallinkofthenociceptionsystem.
G.A.Savchenko, etal.(2010)PurinergicMembraneReceptorsasTargetsfortheEffectofPurotoxin1,aComponentofVenomofSpidersfromthe GeolycosaGenus. Neurophysiology.
NovelpeptidefromspidervenominhibitsP2X3receptorsandinflammatorypain
P2X3purinoreceptorsexpressedinmammaliansensoryneuronsplayakeyroleinseveralprocesses,includingpainperception.FromthevenomoftheCentralAsianspiderGeolycosasp.,wehaveisolatedanovelpeptide,namedpurotoxin-1(PT1),whichistoourknowledgethefirstnaturalmoleculeexertingpowerfulandselectiveinhibitoryactiononP2X3receptors.PT1dramaticallyslowsdowntheremovalofdesensitizationofthesereceptors.Thepeptidedemonstratespotentantinociceptivepropertiesinanimalmodelsofinflammatorypain.
E.V.Grishin, etal.(2010)NovelpeptidefromspidervenominhibitsP2X3receptorsandinflammatorypain. ANNNEUROL. PMID:20437566
