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Toxins 2014, 6(4), 1419-1433; doi:10.3390/toxins6041419
Article

Recombinant Expression and Functional Characterization of Martentoxin: A Selective Inhibitor for BK Channel (α + β4)

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Received: 18 February 2014; in revised form: 27 March 2014 / Accepted: 1 April 2014 / Published: 22 April 2014
(This article belongs to the Special Issue Ion Channel Neurotoxins)
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Abstract: Martentoxin (MarTX), a 37-residue peptide purified from the venom of East-Asian scorpion (Buthus martensi Karsch), was capable of blocking large-conductance Ca2+-activated K+ (BK) channels. Here, we report an effective expression and purification approach for this toxin. The cDNA encoding martentoxin was expressed by the prokaryotic expression system pGEX-4T-3 which was added an enterokinase cleavage site by PCR. The fusion protein (GST-rMarTX) was digested by enterokinase to release hetero-expressed toxin and further purified via reverse-phase HPLC. The molecular weight of the hetero-expressed rMarTX was 4059.06 Da, which is identical to that of the natural peptide isolated from scorpion venom. Functional characterization through whole-cell patch clamp showed that rMarTX selectively and potently inhibited the currents of neuronal BK channels (α + β4) (IC50 = 186 nM), partly inhibited mKv1.3, but hardly having any significant effect on hKv4.2 and hKv3.1a even at 10 μM. Successful expression of martentoxin lays basis for further studies of structure-function relationship underlying martentoxin or other potassium-channel specific blockers.
Keywords: expression and purification; short-chain scorpion toxins; martentoxin; BK channels expression and purification; short-chain scorpion toxins; martentoxin; BK channels
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Tao, J.; Zhou, Z.L.; Wu, B.; Shi, J.; Chen, X.M.; Ji, Y.H. Recombinant Expression and Functional Characterization of Martentoxin: A Selective Inhibitor for BK Channel (α + β4). Toxins 2014, 6, 1419-1433.

AMA Style

Tao J, Zhou ZL, Wu B, Shi J, Chen XM, Ji YH. Recombinant Expression and Functional Characterization of Martentoxin: A Selective Inhibitor for BK Channel (α + β4). Toxins. 2014; 6(4):1419-1433.

Chicago/Turabian Style

Tao, Jie; Zhou, Zhi L.; Wu, Bin; Shi, Jian; Chen, Xiao M.; Ji, Yong H. 2014. "Recombinant Expression and Functional Characterization of Martentoxin: A Selective Inhibitor for BK Channel (α + β4)." Toxins 6, no. 4: 1419-1433.



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