钾离子通道在黄曲霉菌孢子萌发中的作用

Effect of Potassium Ion Channels into the Spore Germination in Aspergillus flavus

摘要:

黄曲霉毒素严重污染农产品，威胁人畜生命健康，而孢子萌发是黄曲霉菌生存及侵染过程中的决定性事件，从最上游阻断孢子萌发可能是有效控制黄曲霉污染、开发新型抗菌药物的突破口之一。研究发现一定浓度的胞外KCl能够影响黄曲霉孢子的萌发。通过使用K+特异性荧光探针PBFI-AM，发现适合孢子萌发的特定浓度K+能够激发黄曲霉孢子瞬间产生较高的钾离子流，说明K⁺响应可能是黄曲霉孢子萌发的早期信号。4-AP作为特异性电压门控钾离子通道阻滞剂，能够明显抑制并延迟孢子的萌发。通过生物信息学预测，发现黄曲霉菌KCNA具有钾离子通道选择器序列，具备电压门控钾离子通道的α亚基属性。进一步构建KCNA非洲爪蟾卵母细胞表达体系，用双电极电压钳系统测得KCNA外向型电流，一定程度上证明了KCNA电压门控钾离子通道蛋白质属性，也说明电压门控钾离子通道参与了黄曲霉孢子萌发。

Abstract:

Aflatoxin seriously polluted agricultural products and threatened the life and health of human and animal. Conidial germination is one of the most decisive factors in survival and invasion of A. flavus，and blocking germination could be one of the effective breakthrough points to keep contamination in the upstream controls. In this study，it was found that extracellular KCl could regulate the conidial germination in A. flavus. By using K+ specific fluorescent probe PBFI-AM，the results showed that a certain concentration of K+，which was suitable for spore germination，can stimulate A. flavus spores to produce higher potassium currents instantly，indicating that K⁺ response may be an early signal of spore germination. As a specific voltage potassium channels blocker，4-AP can obviously inhibit the spore germination. And KCNA is identified with K+-channel filter sequence by using bioinformatics prediction，and further analysis supports the potential of KCNA as voltage-gated potassium channel α subunit. In addition，the ion channel currents of KCNA expressed in Xenopus laevis oocyte were observed using two-electrode voltage clamp. Our studies indicated KCNA involving the regulation of conidial germination in A. flavus，which was one of voltage-gated potassium channels.