Transient cell-specific EXO70A1 activity in the CASP domain and Casparian strip localization
Transient cell-specific EXO70A1 activity in the CASP domain and Casparian strip localization
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DOI：
10.1038/nplants.2017.58
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发表时间：
2017-05-01
期刊：
影响因子：
18
通讯作者：
Geldner, Niko
中科院分区：
文献类型：
--
作者：
Kalmbach, Lothar;Hematy, Kian;Geldner, Niko
在进化趋同的一个引人注目的例子中，具有环状扩散屏障的极化细胞层在植物和动物谱系中都独立进化。在植物中，环状凯氏带由凯氏带膜结构域蛋白（CASP）定位。然而，这种惊人的局部化机制仍然是个谜。在这里，我们提出了一个遗传筛选，旨在隔离CASP定位的决定因素。其中一个突变体，指环王2（lotr2）/exo70a1，显示出戏剧性的CASP去定位到随机定位的微区。EXO70A1是外囊复合物的一个亚基，外囊复合物是真核生物分泌的核心成分。植物中EXO70亚基基因的辐照表明这种保守复合物的特化。有趣的是，lotr 2/exo70a1既不影响CASP的分泌，也不影响内皮层中其他膜蛋白的分泌，从而将定位中的外囊活性与分泌中的一般缺陷分开。我们的研究结果确立了EXO70A1作为凯氏带形成的核心参与者，产生了一个短暂的位置信息，将被翻译成一个精确定位的细胞壁修饰。
In a striking case of evolutionary convergence, polarized cell layers with ring-like diffusion barriers have evolved in both plant and animal lineages independently. In plants, ring-like Casparian strips become localized by the CASPARIAN STRIP MEMBRANE DOMAIN PROTEINS (CASPs). The mechanism of this striking localization, however, has remained enigmatic. Here we present a genetic screen aimed at isolating determinants of CASP localization. One of the mutants, lord of the rings 2 (lotr2)/exo70a1, displays dramatic de-localization of CASPs into randomly localized microdomains. EXO70A1 is a subunit of the exocyst complex, a central component of secretion in eukaryotes. Irradiation of EXO70 subunit genes in plants has suggested specialization of this conserved complex. Intriguingly, lotr2/exo70a1 does neither affect secretion of the CASPs, nor that of other membrane proteins in the endodermis, thus separating exocyst activity in localization from a general defect in secretion. Our results establish EXO70A1 as a central player in Casparian strip formation, generating a transient positional information that will be translated into a precisely localized cell wall modification.