The ω-atracotoxins:: Selective blockers of insect M-LVA and HVA calcium channels
The ω-atracotoxins:: Selective blockers of insect M-LVA and HVA calcium channels
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DOI：
10.1016/j.bcp.2007.05.017
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发表时间：
2007-08-15
影响因子：
5.8
通讯作者：
Nicholson, Graham M.
中科院分区：
文献类型：
--
作者：
Chong, Youmie;Hayes, Jessica L.;Nicholson, Graham M.
Omega-atracotoxins(omega-ACTx)是澳大利亚漏斗网蜘蛛毒液中的一类节肢动物选择性多肽神经毒素，有望作为生物农药开发。我们从悉尼漏斗网蜘蛛Atrax robostus的毒液中分离到一种37个残基的昆虫选择性神经毒素WACTX-Ar1a，与omega-ACTx-1家族的几个成员具有很高的同源性。在家蟋蟀的急性毒性试验中，该肽引起了强烈的兴奋性症状，随后导致松弛麻痹导致死亡。使用分离的平滑肌和骨骼神经-肌肉制剂，该毒素被证明在浓度达1Lm时没有明显的脊椎动物毒性。为了进一步确定omega-ACTXs的靶点，我们对蟑螂背侧受损的正中神经元进行了全细胞膜片钳技术的电压钳分析。首次发现omega-ACTx-Ar1a及其同系物w-ACTx-Hv1a可逆地阻断昆虫钙通道的中低(M-LVA)和高电压(HVA)电流。这种阻断发生在钙-v通道激活的电压依赖性没有改变的情况下，并且是电压不依赖的，这表明omega-ACTx-1家族毒素是孔道阻滞剂而不是门控修饰剂。在1 mU的浓度下，omega-ACTx-Ar1a不能显著影响全球Kv通道电流。然而，1亩M(omega-ACTx-Ar1a)引起18%的昆虫钠通道电流的适度阻断，类似于已报道的其他昆虫钙通道的小阻断，通道阻滞剂如omega-agatoxin IVA。这些发现证实了M-LVA和HVA Cav通道是杀虫剂的潜在靶标。(C)2007年，爱思唯尔公司出版。
The omega-atracotoxins (omega-ACTX) are a family of arthropod-selective peptide neurotoxins from Australian funnel-web spider venoms (Hexathelidae: Atracinae) that are candidates for development as biopesticides. We isolated a 37-residue insect-selective neurotoxin, WACTX-Ar1a, from the venom of the Sydney funnel-web spider Atrax robustus, with high homology to several previously characterized members of the omega-ACTX-1 family. The peptide induced potent excitatory symptoms, followed by flaccid paralysis leading to death, in acute toxicity tests in house crickets. Using isolated smooth and skeletal nerve-muscle preparations, the toxin was shown to lack overt vertebrate toxicity at concentrations up to 1 LM. To further characterize the target of the omega-ACTXs, voltage-clamp analysis using the whole-cell patch-clamp technique was undertaken using cockroach dorsal Impaired median neurons. It is shown here for the first time that omega-ACTX-Ar1a, and its homolog w-ACTX-Hv1a from Hadronyche versuta, reversibly block both mid-low- (M-LVA) and high-voltage-activated (HVA) insect calcium channel (Ca-v) currents. This block occurred in the absence of alterations in the voltage-dependence of Ca-v channel activation, and was voltage-independent, suggesting that omega-ACTX-1 family toxins are pore blockers rather than gating modifiers. At a concentration of 1 mu M omega-ACTX-Ar1a failed to significantly affect global Kv channel currents. However, 1 mu M (omega-ACTX-Ar1a caused a modest 18% block of insect Na, channel currents, similar to the minor block of Na, channels reported for other insect Ca, channel blockers such as omega-agatoxin IVA. These findings validate both M-LVA and HVA Cav channels as potential targets for insecticides. (C) 2007 Published by Elsevier Inc.