Venus Flytrap HKT1-Type Channel Provides for Prey Sodium Uptake into Carnivorous Plant Without Conflicting with Electrical Excitability.
Venus Flytrap HKT1-Type Channel Provides for Prey Sodium Uptake into Carnivorous Plant Without Conflicting with Electrical Excitability.
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DOI：
10.1016/j.molp.2015.09.017
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发表时间：
2016-03-07
期刊：
影响因子：
27.5
通讯作者：
Hedrich R
中科院分区：
文献类型：
--
作者：
Böhm J;Scherzer S;Shabala S;Krol E;Neher E;Mueller TD;Hedrich R
肉食性捕蝇草Dionaea muscipula的动物饮食中含有钠负荷，钠负荷通过hkt1型钠通道进入捕获器官，该通道在捕蝇草叶内表面的特殊上皮细胞中表达。接触猎物后诱导DmHKT1表达和钠摄取活性。在此，我们分析了肉食性狄龙管理猎物渗透钠所需的HKT1特性。分析基于同源性建模，模型衍生点突变体的产生，以及它们在非洲爪蟾卵母细胞中的功能测试。我们发现野生型HKT1及其Na+和K+渗透突变体的功能是离子通道，而不是由质子或钠梯度驱动的K+转运体。高容量、Na+选择性离子通道的这些结构和生物物理特征使Dionaea腺能够管理来自猎物的钠负荷，而不会混淆捕蝇器基于动作电位的信息管理。基于生物物理和基于结构的分析，我们在这里记录了Dionaea腺体操作严格的Na+选择性，高容量离子通道。当受到来自猎物的高钠负荷的挑战时，DmHKT1管理钠摄取，而不会混淆维纳斯捕蝇草基于动作电位的信息管理。
The animal diet of the carnivorous Venus flytrap, Dionaea muscipula, contains a sodium load that enters the capture organ via an HKT1-type sodium channel, expressed in special epithelia cells on the inner trap lobe surface. DmHKT1 expression and sodium uptake activity is induced upon prey contact. Here, we analyzed the HKT1 properties required for prey sodium osmolyte management of carnivorous Dionaea. Analyses were based on homology modeling, generation of model-derived point mutants, and their functional testing in Xenopus oocytes. We showed that the wild-type HKT1 and its Na+- and K+-permeable mutants function as ion channels rather than K+ transporters driven by proton or sodium gradients. These structural and biophysical features of a high-capacity, Na+-selective ion channel enable Dionaea glands to manage prey-derived sodium loads without confounding the action potential-based information management of the flytrap. Based on biophysical- and structure-based analyses we here document that Dionaea glands operate a strictly Na+-selective, high-capacity ion channel. When challenged with high prey-derived sodium loads, DmHKT1 manages sodium uptake without confounding the action -potential-based information management of the Venus flytrap.