The Arabidopsis R-SNARE VAMP721 Interacts with KAT1 and KC1 K+ Channels to Moderate K+ Current at the Plasma Membrane[OPEN]
The Arabidopsis R-SNARE VAMP721 Interacts with KAT1 and KC1 K+ Channels to Moderate K+ Current at the Plasma Membrane[OPEN]
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DOI：
10.1105/tpc.15.00305
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发表时间：
2015-05
期刊：
影响因子：
11.6
通讯作者：
Ben Zhang;Rucha Karnik;Yizhou Wang;Niklas Wallmeroth;M. Blatt;Christopher Grefen
中科院分区：
文献类型：
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作者：
Ben Zhang;Rucha Karnik;Yizhou Wang;Niklas Wallmeroth;M. Blatt;Christopher Grefen
囊泡运输蛋白对K+通道门控的相反作用暗示了囊泡融合过程中结合和通道控制的“切换”。SNARE（可溶性N-乙基马来酰亚胺敏感因子蛋白附着蛋白受体）蛋白驱动囊泡运输，将膜和货物运送到细胞内及其表面的靶位点。它们有助于细胞稳态、形态发生和病原体防御。还已知SNARE的一个子集，包括拟南芥SNARE SYP 121，通过与K+通道的物理相互作用来协调溶质摄取，并调节其在质膜上的门控。在这里，我们确定了第二个子集的陷阱，相互作用，以控制这些K+通道，但与门控相反的行动。我们发现，VAMP（囊泡相关膜蛋白），其目标囊泡的质膜，也相互作用，并抑制内向整流钾离子通道KAT 1和KC 1的活动。相互作用是显而易见的，在酵母分裂泛素测定，它们在体内回收的比率双分子荧光互补，它们是敏感的突变的一个单一的残基，酪氨酸-57，在长域的VAMP 721。在同源物VAMP 723中，在该位点的残基交换也恢复了相互作用，该位点通常定位于内质网，否则不相互作用。功能分析表明，减少通道活动和电压灵敏度的变化，最好的解释是与通道门的物理相互作用。这些行动的补充SYP 121，一个同源SNARE合作伙伴的VAMP 721，并导致我们提出，通道的相互作用反映了“交接”的通道控制之间的两个SNARE蛋白，编织在一起囊泡融合。
Opposing actions of vesicle trafficking proteins on K+ channel gating implicate a ‘handoff’ in binding and channel control during vesicle fusion. SNARE (soluble N-ethylmaleimide-sensitive factor protein attachment protein receptor) proteins drive vesicle traffic, delivering membrane and cargo to target sites within the cell and at its surface. They contribute to cell homeostasis, morphogenesis, and pathogen defense. A subset of SNAREs, including the Arabidopsis thaliana SNARE SYP121, are known also to coordinate solute uptake via physical interactions with K+ channels and to moderate their gating at the plasma membrane. Here, we identify a second subset of SNAREs that interact to control these K+ channels, but with opposing actions on gating. We show that VAMPs (vesicle-associated membrane proteins), which target vesicles to the plasma membrane, also interact with and suppress the activities of the inward-rectifying K+ channels KAT1 and KC1. Interactions were evident in yeast split-ubiquitin assays, they were recovered in vivo by ratiometric bimolecular fluorescence complementation, and they were sensitive to mutation of a single residue, Tyr-57, within the longin domain of VAMP721. Interaction was also recovered on exchange of the residue at this site in the homolog VAMP723, which normally localizes to the endoplasmic reticulum and otherwise did not interact. Functional analysis showed reduced channel activity and alterations in voltage sensitivity that are best explained by a physical interaction with the channel gates. These actions complement those of SYP121, a cognate SNARE partner of VAMP721, and lead us to propose that the channel interactions reflect a “hand-off” in channel control between the two SNARE proteins that is woven together with vesicle fusion.