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

Toxins

Jie Tao¹  Zhi Lei Zhou¹  Bin Wu¹  Jian Shi¹  Xiao Ming Chen¹ 

[1] Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Nanchen Road 333, Shanghai 200444, China;

关键词: expression and purification;    short-chain scorpion toxins;    martentoxin;    BK channels;   

DOI  :  10.3390/toxins6041419

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.