Solution structure of the potassium channel inhibitor agitoxin 2: Caliper for probing channel geometry

Krezel, Andrzej M.; Chandrasekhar, K; Hidalgo, Patricia; MacKinnon, Roderick; Wagner, Gerhard

doi:10.1002/pro.5560040805

Cited by 125 publications

(112 citation statements)

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“…The second part, consisting of residues 13Ϫ32 the Sequelon membrane. Their identities were verified by amino was based on region 19Ϫ38 of agitoxin 2 [58]. This was carried acid analysis and electrospray mass spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

“…This might be due to the hybridisation of the oligo(T) primer used to prime the first strand of cDNA synthesis, to a poly(A) region situated before the polyadenylation short-chain K-toxins [74,91]. All of them present a hydrophobic core as it is a common characteristic of the synthetic toxin analog PO5-NH 2 [57] and of agitoxin 2 [58] as partial templates. Similar to the template for the N-termiof signal peptides [99].…”

Section: Resultsmentioning

confidence: 99%

“…[111]) and Pi1 (30 Å ϫ26 Å ϫ20 Å [29]). In agitoxin 2 a bulge interrupts the first β-strand [58]. The second part comprises resi-The comparison shows that cobatoxins belong to the group of weak blockers of K V 1.1 channels, comparable to charybdotoxin dues 6Ϫ8, which are similar to residues 1Ϫ3 in cobatoxin 1.…”

Section: Resultsmentioning

confidence: 99%

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Cobatoxins 1 and 2 from Centruroides noxius Hoffmann constitute a subfamily of potassium‐channel‐blocking scorpion toxins

Selisko¹,

García²,

Becerril³

et al. 1998

European Journal of Biochemistry

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Potassium-channel-blocking scorpion toxins (A-K-toxins) have been shown to be valuable tools for the study of potassium channels. Here we report two toxins, cobatoxin 1 and 2, of 32 amino acids, containing three disulphide bridges, that were isolated from the venom of the Mexican scorpion Centruroides noxius. Their primary sequences show less than 40% identity to other A-K-toxins. It is therefore proposed that they belong to subfamily 9. The cDNA of cobatoxin 1 encodes a putative signal peptide, a putative short propeptide, the mature peptide and two amino acids that are processed to leave cobatoxin 1 amidated at the C-terminus. In rat brain synaptosomal membranes cobatoxin 1 and cobatoxin 2 bind to a common binding site of A-K-toxins with K i values of 109 pM and 87 pM, respectively. Moreover, they block the Shaker and K V 1.1 K ϩ channels with moderate affinities, with K d values of around 0.7 µM and 4.1 µM (Shaker) and 0.5 µM and 1.0 µM (K V1.1), respectively. A three-dimensional model of cobatoxin 1 was generated and used to interpret the obtained functional data on a structural basis.Keywords : A-K-toxin ; Centruroides noxius ; cobatoxin; potassium channel; scorpion toxin.Potassium channels form a large family of integral mem-surements and mutational analyses, that they block K ϩ channels from the external side, occluding the channel pore [19Ϫ22]. Disbrane proteins that are present in almost every living cell. They play a key physiological role by setting the resting potential and placement experiments on rat brain synaptosomes provide evidence that the receptor site is shared by mast-cell-degranulating shaping bioelectric signals [1,2] PVIIA [27]. Thus, despite these peptides presenting very different three-dimensional folds [14, 28Ϫ34], they seem to act on Neurotoxins that selectively and sensitively block potassium channels (K-toxins) form a structurally diverse group, from K ϩ channels in a similar way. The only exception described has been hanatoxin [35,36]. small peptides to rather complex proteins. Some of them have been shown to be valuable pharmacological tools to study the Scorpion K-toxins were successfully used to identify the pore-forming region of K ϩ channels [20,37], to clarify the strucmolecular structure, function and diversity of K ϩ channels [8,9]. They can be grouped, based on the similarity of their size tural subunit stoichiometry [38], and to identify the functional stoichiometry of inactivation of K ϩ channels [39]. They served and disulphide-bond pattern, into seven groups, which generally reflect their natural origin : scorpion toxins of 31Ϫ39 amino as molecular calipers to measure the dimension of the outer vestibule of the pore of particular channels [40Ϫ47]. Furthermore, acids [9]; dendrotoxins from mamba snakes and kalicludines from sea anemone, of 57Ϫ60 amino acids [10Ϫ12] ; small pep-they were used for the purification, isolation [24, 48Ϫ50] and pharmacological classification of K ϩ channels [8], and to study tides of 18Ϫ22 amino acids isolated from bee venom, including ma...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Cobatoxins 1 and 2 from Centruroides noxius Hoffmann constitute a subfamily of potassium‐channel‐blocking scorpion toxins

Selisko¹,

García²,

Becerril³

et al. 1998

European Journal of Biochemistry

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“…The specificity of scorpion toxin for the various potassium channels has been extensively investigated. The results revealed that binding of the peptide is governed by electrostatic interactions between negatively charged residues in the channel and positively charged residues in the peptide (36,37). The surface electrostatic distribution shown in Fig.…”

Section: Fig 5 Bmp09 Has No Effect On Ca 2؉ -Independent But Voltagmentioning

confidence: 91%

BmP09, a “Long Chain” Scorpion Peptide Blocker of BK Channels

Yao

Chen

et al. 2005

Journal of Biological Chemistry

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A novel "long chain" toxin BmP09 has been purified and characterized from the venom of the Chinese scorpion Buthus martensi Karsch. The toxin BmP09 is composed of 66 amino acid residues, including eight cysteines, with a mass of 7721.0 Da. Compared with the B. martensi Karsch AS-1 as a Na ؉ channel blocker (7704.8 Da), the BmP09 has an exclusive difference in sequence by an oxidative modification at the C terminus. The sulfoxide Met-66 at the C terminus brought the peptide a dramatic switch from a Na ؉ channel blocker to a K ؉ channel blocker. Upon probing the targets of the toxin BmP09 on the isolated mouse adrenal medulla chromaffin cells, where a variety of ion channels coexists, we found that the toxin BmP09 specifically blocked large conductance Ca 2؉ -and voltage-dependent K ؉ channels (BK) but not Na ؉ channels at a range of 100 nM concentration. This was further confirmed by blocking directly the BK channels encoded with mSlo1 ␣-subunits in Xenopus oocytes. The half-maximum concentration EC 50 of BmP09 was 27 nM, and the Hill coefficient was 1.8. In outside-out patches, the 100 nM BmP09 reduced ϳ70% currents of BK channels without affecting the single-channel conductance. In comparison with the "short chain" scorpion peptide toxins such as Charybdotoxin, the toxin BmP09 behaves much better in specificity and reversibility, and thus it will be a more efficient tool for studying BK channels. A three-dimensional simulation between a BmP09 toxin and an mSlo channel shows that the Lys-41 in BmP09 lies at the center of the interface and plugs into the entrance of the channel pore. The stable binding between the toxin BmP09 and the BK channel is favored by aromatic -interactions around the center.

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“…The 3-D structures of several short toxins such as charybdotoxin (ChTX) [17], iberiotoxin (IbTx) [31], kaliotoxin (KxTx) [32,33] margatoxin (MgTx) [34], maurotoxin [35], agitoxin (AgTx) [36], noxiustoxin (NTX) [37], PiL [10], insectotoxin I5A [22], LQH-8/6 [27] and chlorotoxin [38] have been determined by NMR spectroscopy and X-ray crystallography. A structure model of ButaIT, generated from the Swiss-…”

Section: Structural Analysismentioning

confidence: 99%

Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus

et al. 2001

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Solution structure of the potassium channel inhibitor agitoxin 2: Caliper for probing channel geometry

Cited by 125 publications

References 40 publications

Cobatoxins 1 and 2 from Centruroides noxius Hoffmann constitute a subfamily of potassium‐channel‐blocking scorpion toxins

Cobatoxins 1 and 2 from Centruroides noxius Hoffmann constitute a subfamily of potassium‐channel‐blocking scorpion toxins

BmP09, a “Long Chain” Scorpion Peptide Blocker of BK Channels

Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus

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