An organelle K+ channel is required for osmoregulation in Chlamydomonas reinhardtii
An organelle K+ channel is required for osmoregulation in Chlamydomonas reinhardtii
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DOI：
10.1242/jcs.188441
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发表时间：
2016-08
影响因子：
4
通讯作者：
Feifei Xu;Xiaoan Wu;Lin-Hua Jiang;Hucheng Zhao;Junmin Pan
中科院分区：
文献类型：
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作者：
Feifei Xu;Xiaoan Wu;Lin-Hua Jiang;Hucheng Zhao;Junmin Pan
淡水原生动物和藻类在其生存环境中面临低渗挑战。它们中的许多采用收缩液泡系统从细胞质中吸收多余的水分并将其排出到环境中以实现细胞内稳态。K+是可收缩液泡中的主要渗透物，预计会对水的流入产生更高的渗透压。K+通过质膜的分子机制已经得到了很好的研究。然而，K+如何渗透细胞器，如收缩液泡，尚不清楚。在这里，我们发现衣藻的六跨膜K+通道KCN11仅局限于收缩液泡。KCN11在HEK293T细胞中的异位表达导致电压门控的K+通道活性。在极低渗条件下，钾离子通道通透性关键残基的基因破坏或突变导致细胞渗透调节功能障碍。突变细胞的收缩周期受到抑制，收缩液泡膨胀速度减慢，导致细胞死亡。这些数据证明了6个跨膜K+通道在收缩液泡功能中的新作用，并为收缩液泡介导的渗透调节提供了进一步的见解。摘要：我们发现了一个新的K+通道，标记为KCN11，它定位于收缩液泡，并在莱茵衣藻的收缩液泡收缩和渗透调节中起作用。
ABSTRACT Fresh water protozoa and algae face hypotonic challenges in their living environment. Many of them employ a contractile vacuole system to uptake excessive water from the cytoplasm and expel it to the environment to achieve cellular homeostasis. K+, a major osmolyte in contractile vacuole, is predicted to create higher osmolarity for water influx. Molecular mechanisms for K+ permeation through the plasma membrane have been well studied. However, how K+ permeates organelles such as the contractile vacuole is not clear. Here, we show that the six-transmembrane K+ channel KCN11 in Chlamydomonas is exclusively localized to contractile vacuole. Ectopic expression of KCN11 in HEK293T cells results in voltage-gated K+ channel activity. Disruption of the gene or mutation of key residues for K+ permeability of the channel leads to dysfunction of cell osmoregulation in very hypotonic conditions. The contractile cycle is inhibited in the mutant cells with a slower rate of contractile vacuole swelling, leading to cell death. These data demonstrate a new role for six-transmembrane K+ channels in contractile vacuole functioning and provide further insights into osmoregulation mediated by the contractile vacuole. Summary: We identify a new K+ channel, denoted KCN11, that is localized to the contractile vacuole, and functions in contractile vacuole contraction and osmoregulation in Chlamydomonas reinhardtii.