The Arabidopsis Intracellular Na+/H+ Antiporters NHX5 and NHX6 Are Endosome Associated and Necessary for Plant Growth and Development
The Arabidopsis Intracellular Na+/H+ Antiporters NHX5 and NHX6 Are Endosome Associated and Necessary for Plant Growth and Development
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DOI：
10.1105/tpc.110.079426
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发表时间：
2011-01-01
期刊：
影响因子：
11.6
通讯作者：
Blumwald, Eduardo
中科院分区：
文献类型：
--
作者：
Bassil, Elias;Ohto, Masa-aki;Blumwald, Eduardo
细胞内Na+/H+反向转运蛋白（NHX）在真核生物细胞内pH和Na+、K+稳态中起重要作用。基于序列相似性，六个细胞内拟南芥成员分为两组。与液泡NHX 1 -4不同，NHX 5和NHX 6被认为是内体的;然而，几乎没有数据支持它们的功能或定位。使用反向遗传学，我们发现，而单敲除nhx 5或nhx 6没有从野生型不同，双敲除nhx 5 nhx 6显示出减少增长，更小，更少的细胞和增加对盐度的敏感性。nhx 5和nhx 6的生长减少是由于细胞扩增减慢。转录组分析表明，nhx 5，nhx 6，和野生型有相似的基因表达谱，而转录相关的囊泡运输和非生物胁迫富集在nhx 5 nhx 6。我们发现，与其他细胞内NHX蛋白，NHX 5和NHX 6与点状，能动的胞质小泡，布雷菲德菌素A敏感，共定位到已知的高尔基体和反高尔基体网络标记。我们提供的数据表明，液泡运输的影响，在nhx 5 nhx 6。NHX 5和NHX 6在维持细胞器pH值和离子稳态与内涵体分选和细胞应激反应的影响可能的参与进行了讨论。
Intracellular Na+/H+ antiporters (NHXs) play important roles in cellular pH and Na+ and K+ homeostasis in all eukaryotes. Based on sequence similarity, the six intracellular Arabidopsis thaliana members are divided into two groups. Unlike the vacuolar NHX1-4, NHX5 and NHX6 are believed to be endosomal; however, little data exist to support either their function or localization. Using reverse genetics, we show that whereas single knockouts nhx5 or nhx6 did not differ from the wild type, the double knockout nhx5 nhx6 showed reduced growth, with smaller and fewer cells and increased sensitivity to salinity. Reduced growth of nhx5 nhx6 was due to slowed cell expansion. Transcriptome analysis indicated that nhx5, nhx6, and the wild type had similar gene expression profiles, whereas transcripts related to vesicular trafficking and abiotic stress were enriched in nhx5 nhx6. We show that unlike other intracellular NHX proteins, NHX5 and NHX6 are associated with punctate, motile cytosolic vesicles, sensitive to Brefeldin A, that colocalize to known Golgi and trans-Golgi network markers. We provide data to show that vacuolar trafficking is affected in nhx5 nhx6. Possible involvements of NHX5 and NHX6 in maintaining organelle pH and ion homeostasis with implications in endosomal sorting and cellular stress responses are discussed.