The Signature Sequence of Voltage-gated Potassium Channels Projects into the External Vestibule

Aiyar, Jayashree; Rizzi, James P.; Gutman, George A.; Chandy, K. George

doi:10.1074/jbc.271.49.31013

Cited by 129 publications

(140 citation statements)

References 25 publications

(63 reference statements)

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“…Similarly, and based on the 4-fold symmetry of the Kv1.3 channel, the His-39 in MgTX may also be fitted with the three previous residues if a /2 rotation around the central Lys-27 of MgTX is done. The distance between the C␣ of the lysine and the center of the imidazole or guanidinium group was estimated to be 13 Ϯ 1 Å. Interestingly, in agreement with our comparison, it has been suggested, using quantitative methods, that Arg-24 in KTX interacts electrostatically with Asp-386 and His-404 of Kv1.3 (16) and that Arg-11 of ShK interacts with His-404 (27).…”

Section: Contribution Of the Diad Lys-25/tyr-26 In The Bgksupporting

confidence: 88%

“…The sequences of the rat and human Kv1.1 cDNAs are identical between the second and the sixth transmembrane segments, and the binding sites of various sea anemone and scorpion toxins have been identified between the fifth and the sixth transmembrane segment of Kv1 channels (14 -17, 27). Variation in the affinity of charybdotoxin, ␣DTX and 4-aminopyridine for Kv channels has been observed depending on the expression system used, either in mammalian cell lines or in Xenopus oocytes (1,13,16,24,35). Moreover, the expression of the rat Kv1.2 cDNA in the B82 cells instead of Xenopus oocytes increased by 28-fold the K D of the BgK (see the following section).…”

Section: Identification Of Bgk Residues Involved In the Binding To Kvmentioning

confidence: 99%

“…Elements of the Kv1.3 binding sites of ShK (50), kaliotoxin (KTX) (16), and margatoxin (MgTX) (47) have been identified using mutagenesis on the blockers combined with either electrophysiological or binding experiments. The binding site of ShK comprises the three basic residues Lys-9, Arg-11, and Lys-22 and probably Tyr-23 (50), that of KTX comprises Lys-27 and probably Arg-24 and Phe-25, and that of MgTX comprises Lys-28, Met-30, Asn-31, His-39, and Tyr-37.…”

Section: Contribution Of the Diad Lys-25/tyr-26 In The Bgkmentioning

confidence: 99%

“…This surface seems to include in both scorpion and sea anemone blockers a central lysine plugging the pore (16,27) assisted by an aromatic residue at 6 Ϯ 1 Å, a polar binding site at 9 Ϯ 1 Å, and a distal basic residue at 13 Ϯ 1 Å.…”

Section: Contribution Of the Diad Lys-25/tyr-26 In The Bgkmentioning

confidence: 99%

“…The most likely role for these residues is to interact with residues common to all the different Kv1 subtypes to which these blockers bind. It has been shown, using mutant cycle-based analysis, that the lysine of the diad from the sea anemone blocker ShK (27) and of the scorpion blockers Agitoxin 2 (17) and KTX (16) interact with the conserved tyrosine of the selectivity filter of voltage-gated potassium channels (51). Furthermore, it has been shown that the hydrophobic residue of the diad of agitoxin2 (Phe-25) interacts with the conserved methionine residue from the same channel region (17).…”

Section: Implications For the Design Of Blockers With Enhanced Selectmentioning

confidence: 99%

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Mapping the Functional Anatomy of BgK on Kv1.1, Kv1.2, and Kv1.3

Alessandri‐Haber

Lecoq

Gasparini

et al. 1999

Journal of Biological Chemistry

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BgK is a peptide from the sea anemone Bunodosoma granulifera, which blocks Kv1.1, Kv1.2, and Kv1.3 potassium channels. Using 25 analogs substituted at a single position by an alanine residue, we performed the complete mapping of the BgK binding sites for the three Kv1 channels. These binding sites included three common residues (Ser-23, Lys-25, and Tyr-26) and a variable set of additional residues depending on the particular channel. Shortening the side chain of Lys-25 by taking out the four methylene groups dramatically decreased the BgK affinity to all Kv1 channels tested. However, the analog K25Orn displayed increased potency on Kv1.2, which makes this peptide a selective blocker for Kv1.2 (K D 50-and 300-fold lower than for Kv1.1 and Kv1.3, respectively). BgK analogs with enhanced selectivity could also be made by substituting residues that are differentially involved in the binding to some of the three Kv1 channels. For example, the analog F6A was found to be >500-fold more potent for Kv1.1 than for Kv1.2 and Kv1.3. These results provide new information about the mechanisms by which a channel blocker distinguishes individual channels among closely related isoforms and give clues for designing analogs with enhanced selectivity.

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Section: Contribution Of the Diad Lys-25/tyr-26 In The Bgksupporting

confidence: 88%

Section: Identification Of Bgk Residues Involved In the Binding To Kvmentioning

confidence: 99%

Section: Contribution Of the Diad Lys-25/tyr-26 In The Bgkmentioning

confidence: 99%

Section: Contribution Of the Diad Lys-25/tyr-26 In The Bgkmentioning

confidence: 99%

Section: Implications For the Design Of Blockers With Enhanced Selectmentioning

confidence: 99%

See 3 more Smart Citations

Mapping the Functional Anatomy of BgK on Kv1.1, Kv1.2, and Kv1.3

Alessandri‐Haber

Lecoq

Gasparini

et al. 1999

Journal of Biological Chemistry

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Solution structure of BmKTX, a K+ blocker toxin from the Chinese scorpionButhus Martensi

Renisio¹,

Romi-Lebrun²,

Blanc³

et al. 2000

Proteins

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BmKTX is a toxin recently purified from the venom of Buthus Martensi, which belongs to the kaliotoxin family. We have determined its solution structure by use of conventional two-dimensional NMR techniques followed by distance-geometry and energy minimization. The calculated structure is composed of a short alpha-helix (residues 14 to 20) connected by a tight turn to a two-stranded antiparallel beta-sheet (sequences 25-27 and 32-34). The beta-turn connecting these strands belongs to type I. The N-terminal segment (sequence 1 to 8) runs parallel to the beta-sheet although it cannot be considered as a third strand. Comparison of the conformation of BmKTX and toxins of the kaliotoxin family clearly demonstrates that they are highly related. Therefore, analysis of the residues belonging to the interacting surface of those toxins allows us to propose a functional map of BmKTX slightly different from the one of KTX and AgTX2, which may explain the variations in affinities of these toxins towards the Kv1.3 channels.

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Structural and functional differences of two toxins from the scorpionPandinus imperator

et al. 2000

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The Pandinotoxins, PiTX-K alpha and PiTX-K beta, are members of the Charybdotoxin family of scorpion toxins that can be used to characterize K+ channels. PiTX-K alpha differs from PiTX-K beta, another peptide from Pandinus imperator, by one residue (P10E). When the two toxins are compared in a physiological assay, the affinity of PiTX-K beta for voltage-gated, rapidly inactivating K+ channels in dorsal root ganglia (DRG) neurons is 800-fold lower than that of PiTX-K alpha (K alpha-IC50 = 8.0 nM versus K beta-IC50 = 6,500 nM). To understand this difference, the three-dimensional structure of PiTX-K beta was determined by nuclear magnetic resonance (NMR) spectroscopy and compared to that of PiTX-K alpha. This comparison shows that structural differences between the two toxins occur at a residue that is critical for blocking K+ channels (K27) as well as at the site of the natural mutation (P10E). In PiTX-K beta, the negatively charged carboxylate oxygen of E10 can approach the positive charge of K27 and presumably reduces the net positive charge in this region of the toxin. This is likely the reason why PiTX-K beta binds K+ channels from DRG neurons with a much lower affinity than does PiTX-K alpha.

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The Signature Sequence of Voltage-gated Potassium Channels Projects into the External Vestibule

Cited by 129 publications

References 25 publications

Mapping the Functional Anatomy of BgK on Kv1.1, Kv1.2, and Kv1.3

Mapping the Functional Anatomy of BgK on Kv1.1, Kv1.2, and Kv1.3

Solution structure of BmKTX, a K+ blocker toxin from the Chinese scorpionButhus Martensi

Structural and functional differences of two toxins from the scorpionPandinus imperator

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