AtNHX5 and AtNHX6 Are Required for the Subcellular Localization of the SNARE Complex That Mediates the Trafficking of Seed Storage Proteins in Arabidopsis.
AtNHX5 and AtNHX6 Are Required for the Subcellular Localization of the SNARE Complex That Mediates the Trafficking of Seed Storage Proteins in Arabidopsis.
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DOI：
10.1371/journal.pone.0151658
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Qiu QS
中科院分区：
文献类型：
--
作者：
Wu X;Ebine K;Ueda T;Qiu QS
由VAMP727、SYP22、VTI11和SYP51组成的SNARE复合体在拟南芥蛋白质运输和PSV生物合成中起关键作用。该SNARE复合物指导液泡前区室（PVC）和液泡之间的融合，从而介导蛋白质运输到液泡。在这项研究中，我们研究了AtNHX5和AtNHX6在调节这种SNARE复合物及其在蛋白质运输中的功能中的作用。我们发现AtNHX5和AtNHX6是种子生产、蛋白运输和PSV生物合成所必需的。我们进一步发现nhx5 nhx6 syp22三重突变体在幼苗生长和种子发育方面表现出严重的缺陷。三重突变体角果短，结实减少，但种子较大。此外，三突变体具有许多较小的蛋白贮藏液泡（PSV），并在种子中积累了种子贮藏蛋白的前体。SYP22和VAMP727的PVC定位在nhx5 nhx6中被抑制，而大量的SYP22和VAMP727在nhx5 nhx6中被捕获在高尔基体或TGN中。AtNHX 5和AtNHX 6与SYP22和VAMP 727共定位。AtNHX5中的D164、E188和D193以及AtNHX6中的D165、E189和D194这三个保守的酸性残基对贮藏蛋白的转运是必需的，表明交换活性在蛋白转运中的重要性。AtNHX5或AtNHX6不与SNARE复合物发生物理相互作用。两者合计，AtNHX5和AtNHX6是需要的陷阱复合物的PVC定位，因此其在蛋白质转运的功能。AtNHX5和AtNHX6可能通过其转运活性调节SNARE复合物的亚细胞定位。
The SNARE complex composed of VAMP727, SYP22, VTI11 and SYP51 is critical for protein trafficking and PSV biogenesis in Arabidopsis. This SNARE complex directs the fusion between the prevacuolar compartment (PVC) and the vacuole, and thus mediates protein trafficking to the vacuole. In this study, we examined the role of AtNHX5 and AtNHX6 in regulating this SNARE complex and its function in protein trafficking. We found that AtNHX5 and AtNHX6 were required for seed production, protein trafficking and PSV biogenesis. We further found that the nhx5 nhx6 syp22 triple mutant showed severe defects in seedling growth and seed development. The triple mutant had short siliques and reduced seed sets, but larger seeds. In addition, the triple mutant had numerous smaller protein storage vacuoles (PSVs) and accumulated precursors of the seed storage proteins in seeds. The PVC localization of SYP22 and VAMP727 was repressed in nhx5 nhx6, while a significant amount of SYP22 and VAMP727 was trapped in the Golgi or TGN in nhx5 nhx6. AtNHX5 and AtNHX6 were co-localized with SYP22 and VAMP727. Three conserved acidic residues, D164, E188, and D193 in AtNHX5 and D165, E189, and D194 in AtNHX6, were essential for the transport of the storage proteins, indicating the importance of exchange activity in protein transport. AtNHX5 or AtNHX6 did not interact physically with the SNARE complex. Taken together, AtNHX5 and AtNHX6 are required for the PVC localization of the SNARE complex and hence its function in protein transport. AtNHX5 and AtNHX6 may regulate the subcellular localization of the SNARE complex by their transport activity.