Self-Incompatibility in Papaver rhoeas Activates Nonspecific Cation Conductance Permeable to Ca2+ and K+[W]
Self-Incompatibility in Papaver rhoeas Activates Nonspecific Cation Conductance Permeable to Ca2+ and K+[W]
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DOI：
10.1104/pp.110.161927
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发表时间：
2010-12
期刊：
影响因子：
7.4
通讯作者：
Juyou Wu;Su-yang Wang;Yuchun Gu;Shaoling Zhang;S. Publicover;V. Franklin-Tong
中科院分区：
文献类型：
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作者：
Juyou Wu;Su-yang Wang;Yuchun Gu;Shaoling Zhang;S. Publicover;V. Franklin-Tong
细胞反应依赖于信号。在植物细胞中，胞浆游离钙是一种主要的第二信使，离子通道在介导生理反应中起着关键作用。自交不亲和性（SI）是防止自交不亲和的重要遗传机制。它利用来自雌蕊和花粉的匹配S-决定子的相互作用来允许“自我”识别，这触发了对不相容花粉的排斥。在虞美人中，S-决定簇是PrsS和PrpS。PrsS是一种新型的富含半胱氨酸的小蛋白; PrpS是一种新型的跨膜小蛋白。PrsS与不相容花粉的相互作用刺激S-特异性增加细胞质游离钙和肌动蛋白细胞骨架的改变，导致程序性细胞死亡不相容，但不兼容的花粉。在这里，我们已经使用全细胞膜片钳花粉原生质体显示，PrsS刺激SI特异性激活花粉粒质膜电导不兼容，但不兼容的花粉粒原生质体。SI激活的电导不需要电压激活，但它是电压敏感的。它对二价阳离子（Ba 2 + ≥ Ca 2 + > Mg 2+）和一价离子K+和NH 4+是可渗透的，并且在负至−100 mV的电压下增强。Ca 2+电导被La 3+阻断，但不被维拉帕米阻断; K+电流对氯化四乙基铵不敏感，不需要Ca 2+。我们建议，SI刺激的电导可能代表一个非特异性阳离子通道或可能两个电导，可渗透到一价和二价阳离子。我们的数据提供了深入了解涉及生物学上重要的反应的信号-反应耦合。PrsS提供了一个罕见的蛋白质触发离子通道活性改变的例子。
Cellular responses rely on signaling. In plant cells, cytosolic free calcium is a major second messenger, and ion channels play a key role in mediating physiological responses. Self-incompatibility (SI) is an important genetically controlled mechanism to prevent self-fertilization. It uses interaction of matching S-determinants from the pistil and pollen to allow “self” recognition, which triggers rejection of incompatible pollen. In Papaver rhoeas, the S-determinants are PrsS and PrpS. PrsS is a small novel cysteine-rich protein; PrpS is a small novel transmembrane protein. Interaction of PrsS with incompatible pollen stimulates S-specific increases in cytosolic free calcium and alterations in the actin cytoskeleton, resulting in programmed cell death in incompatible but not compatible pollen. Here, we have used whole-cell patch clamping of pollen protoplasts to show that PrsS stimulates SI-specific activation of pollen grain plasma membrane conductance in incompatible but not compatible pollen grain protoplasts. The SI-activated conductance does not require voltage activation, but it is voltage sensitive. It is permeable to divalent cations (Ba2+ ≥ Ca2+ > Mg2+) and the monovalent ions K+ and NH4+ and is enhanced at voltages negative to −100 mV. The Ca2+ conductance is blocked by La3+ but not by verapamil; the K+ currents are tetraethylammonium chloride insensitive and do not require Ca2+. We propose that the SI-stimulated conductance may represent a nonspecific cation channel or possibly two conductances, permeable to monovalent and divalent cations. Our data provide insights into signal-response coupling involving a biologically important response. PrsS provides a rare example of a protein triggering alterations in ion channel activity.