ASIC1a&1bchannelblocker
Mambalgin-1wasinitiallyisolatedbySylvieDiochotandcollaboratorsfromthevenomoftheblackmamba(Dendroaspispolylepispolylepis).Mambalgin-1isapotentandselectiveblockerofacid-sensingionchannels(ASIC).ASICchannelshavebeendemonstratedtobeimpliedinpainpathwaysandappeartobepromisingtherapeutictargets. Mambalgin-1rapidlyandreversIBLyinhibitsrecombinanthomomericASIC1a(IC50=55nM)andheteromericASIC1a+ASIC2a(IC50=246nM)orASIC1a+ASIC2bchannels(IC50=61nM)butalsohumanchannelshASIC1b(IC50=192nM)and hASIC1a+hASIC1b(IC50=72nM).
Mambalgin-1belongstothefamilyofthree-fingertoxinsandhasnosequence/structuralhomologywitheitherPcTx1orAPETx2.Mambalgin-1differsfrommambalgin-2byoneaminoacid.Bothhavedemonstratedasimilaractivity.Mambalgin-1hasnoeffectonASIC2a,ASIC3,ASIC1a+ASIC3andASIC1b+ASIC3channels,aswellasonTRPV1,P2X2,5-HT3A,Nav1.8,Cav3.2andKv1.2channels.
Recentlyquoted
Fig1: Dose-responsecurveoftheeffectofsyntheticMambalgin-1#MAM001onASIC1acurrentrecordedin Xenopusoocytes.Inthissystem,anIC50of21nMwasdetermined.
Description:
AAsequence:LKC3YQHGKVVTC12HRDMKFC19YHNTGMPFRNLKLILQGC37SSSC41SETENNKC49C50STDRC55NK-OH
Disulfidebonds:Cys3-Cys19,Cys12-Cys37,Cys41-Cys49,Cys50-Cys55
Length(aa):57
Formula: C272H429N85O84S10
MolecularWeight: 6554.59Da
Appearance:whitelyophilizedsolid
Solubility: waterorsalinebuffer
CASnumber:notavailable
Source:synthetic
Purityrate: >98%
Reference:
Blackmambavenompeptidestargetacid-sensingionchannelstoabolishpain.
Polypeptidetoxinshaveplayedacentralpartinunderstandingphysiologicalandphysiopathologicalfunctionsofionchannels.Inthefieldofpain,theyledtoimportantadvancesinbasicresearchandeventoclinicalapplications.Acid-sensingionchannels(ASICs)aregenerallyconsideredprincipalplayersinthepainpathway,includinginhumans.AsnaketoxinactivatingperipheralASICsinnociceptiveneuronshasbeenrecentlyshowntoevokepain.Hereweshowthatanewclassofthree-fingerpeptidesfromanothersnake,theblackmamba,isabletoabolishpainthroughinhibitionofASICsexpressedeitherincentralorperipheralneurons.Thesepeptides,whichwecallmambalgins,arenottoxicinmicebutshowapotentanalgesiceffectuponcentralandperipheralinjectionthatcanbeasstrongasmorphine.Thiseffectis,however,resistanttonaloxone,andmambalginscausemuchlesstolerancethanmorphineandnorespiratorydistress.PharmacologicalinhibitionbymambalginscombinedwiththeuseofknockdownandknockoutanimalsindicatesthatblockadeofheteromericchannelsmadeofASIC1aandASIC2asubunitsincentralneuronsandofASIC1b-containingchannelsinnociceptorsisinvolvedintheanalgesiceffectofmambalgins.Thesefindingsidentifynewpotentialtherapeutictargetsforpainandintroducenaturalpeptidesthatblockthemtoproduceapotentanalgesia.
CharacterizationofhASIC1achannelsupontoxinmambalgin-1bindinginlivemammaliancells
WenM.,etal. (2015)Site-specificfluorescencespectrumdetectionandcharacterizationofhASIC1achannelsupontoxinmambalgin-1bindinginlivemammaliancells.ChemCommun.PMID: 25873388
Thesynthesisoffluorescentunnaturalamino-acidAnapwasoptimizedandtheAnapwasincorporatedintofoursitesinanacid-pocketoratransmembraneregionofhumanacid-sensingionchannel-1a(hASIC1a).CombinationalAnapfluorescencespectraandpatch-clampelectrophysiologydataillustratedsite-specificconformationalresponsesupontoxinmambalgin-1binding.Thiscombinationalapproachcanbeusedtoanalyseconformationalpropertiesofmanydifferenteukaryoticproteinsintheirfunctionalstates,inasite-specificmannerinlivemammaliancells.
Bindingsiteandinhibitorymechanismofthemambalgin-2
SalinasM.,etal.(2014)Bindingsiteandinhibitorymechanismofthemambalgin-2pain-relievingpeptideonacid-sensingionchannel1a.JBC.PMID:24695733
Acid-sensingionchannels(ASICs)areneuronalproton-gatedcationchannelsassociatedwithnociception,fear,depression,seizure,andneuronaldegeneration,suggestingrolesinpainandneurologicalandpsychiatricdisorders.Wehaverecentlydiscoveredblackmambavenompeptidescalledmambalgin-1andmambalgin-2,whicharenewthree-fingertoxinsthatspecificallyinhibitwiththesamepharmacologicalprofileASICchannelstoexertstronganalgesiceffectsinvivo.Wenowcombinedbioinformaticsandfunctionalapproachestouncoverthemolecularmechanismofchannelinhibitionbythemambalgin-2pain-relievingpeptide.Mambalgin-2bindsmainlyinaregionofASIC1ainvolvingtheupperpartofthethumbdomain(residuesAsp-349andPhe-350),thepalmdomainofanadjacentsubunit,andtheβ-balldomain(residuesArg-190,Asp-258,andGln-259).Thisregionoverlapswiththeacidicpocket(pHsensor)ofthechannel.ThepeptideexertsbothstimulatoryandinhibitoryeffectsonASIC1a,andweproposeamodelwheremambalgin-2trapsthechannelinaclosedconformationbyprecludingtheconformationalchangeofthepalmandβ-balldomainsthatfollowsprotonactivation.ThesedatahelptounderstandinhibitionbymambalginsandprovidecluesforthedevelopmentofnewoptimizedblockersofASICchannels.
