Envelope K+/H+ Antiporters AtKEA1 and AtKEA2 Function in Plastid Development1[OPEN]
Envelope K+/H+ Antiporters AtKEA1 and AtKEA2 Function in Plastid Development1[OPEN]
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DOI：
10.1104/pp.16.00995
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发表时间：
2016-07
期刊：
影响因子：
7.4
通讯作者：
M. N. Aranda-Sicilia;Ali Aboukila;Ute Armbruster;Olivier Cagnac;Tobias Schumann;Hans-Henning Kunz;P. Jahns;M. Rodríguez-Rosales;H. Sze;K. Venema
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文献类型：
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作者：
M. N. Aranda-Sicilia;Ali Aboukila;Ute Armbruster;Olivier Cagnac;Tobias Schumann;Hans-Henning Kunz;P. Jahns;M. Rodríguez-Rosales;H. Sze;K. Venema
定位于分裂和发育质体极性微区的反向转运蛋白影响类囊体膜的形成和叶绿体分化。叶绿体的类囊体膜能将光能转化为化学能，但对叶绿体和类囊体膜的发育却知之甚少。两个包膜K+/H+反向转运蛋白AtKEA 1和AtKEA 2的功能丧失以前被证明对光合作用和植物生长的效率有负面影响;然而，分子基础仍不清楚。在这里，我们测试了先前描述的双突变体kea 1 kea 2植物的表型是否部分是由于在拟南芥（拟南芥）早期叶绿体发育过程中的缺陷。我们发现，受损的生长和色素沉着是特别明显的kea 1 kea 2突变体在年轻的扩展叶。在增殖的叶区，叶绿体含有低得多的光合复合物和叶绿素。引人注目的是，AtKEA 1和AtKEA 2蛋白质在小的分裂质体中积累到很高的量，在那里它们特异性地定位于被分裂平面分开的细胞器的两个帽。在反向转运结构域之前的550个残基的异常长的氨基末端结构域似乎将全长AtKEA 2蛋白拴系到两个帽上。最后，我们表明，双突变体含有30%，每个细胞少叶绿体。总之，这些结果表明，AtKEA 1和AtKEA 2转运蛋白在特定的微结构域的内包膜链接当地的渗透，离子和pH值的稳态质体分裂和类囊体膜的形成。
Antiporters localized to polar microdomains of dividing and developing plastids affect thylakoid membrane formation and chloroplast differentiation. It is well established that thylakoid membranes of chloroplasts convert light energy into chemical energy, yet the development of chloroplast and thylakoid membranes is poorly understood. Loss of function of the two envelope K+/H+ antiporters AtKEA1 and AtKEA2 was shown previously to have negative effects on the efficiency of photosynthesis and plant growth; however, the molecular basis remained unclear. Here, we tested whether the previously described phenotypes of double mutant kea1kea2 plants are due in part to defects during early chloroplast development in Arabidopsis (Arabidopsis thaliana). We show that impaired growth and pigmentation is particularly evident in young expanding leaves of kea1kea2 mutants. In proliferating leaf zones, chloroplasts contain much lower amounts of photosynthetic complexes and chlorophyll. Strikingly, AtKEA1 and AtKEA2 proteins accumulate to high amounts in small and dividing plastids, where they are specifically localized to the two caps of the organelle separated by the fission plane. The unusually long amino-terminal domain of 550 residues that precedes the antiport domain appears to tether the full-length AtKEA2 protein to the two caps. Finally, we show that the double mutant contains 30% fewer chloroplasts per cell. Together, these results show that AtKEA1 and AtKEA2 transporters in specific microdomains of the inner envelope link local osmotic, ionic, and pH homeostasis to plastid division and thylakoid membrane formation.