Conversion of functional specificity in Qb-SNARE VTI1 homologues of Arabidopsis
Conversion of functional specificity in Qb-SNARE VTI1 homologues of Arabidopsis
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DOI：
10.1016/j.cub.2005.02.021
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发表时间：
2005-03-29
期刊：
影响因子：
9.2
通讯作者：
Morita, MT
中科院分区：
文献类型：
--
作者：
Niihama, M;Uemura, T;Morita, MT
在高等多细胞真核生物中，需要高度专门化的膜结构或膜转运事件来支持各种生理功能。SNARES(可溶性NSF附着蛋白受体)在特异性膜融合中起重要作用。这些蛋白受体根据其特定的SNARE结构基序被归类为QA-、QB-、QC-和R-SNARE亚群。位于靶膜上的一组特定的QA-、QB-和QC-SNARE与囊泡上的R-SNARE相互作用形成紧密的复合体，导致膜融合[1-4]。缺失QB-SNARE VTI11的拟南芥ZIG-1突变体表现出较小的向重力性和异常的茎形态。VTI11及其同源物VTI12部分重叠但在细胞内定位不同，在植物中具有不同的生物学功能[5-10]。关于陷阱是如何针对特定细胞器的，人们知之甚少，尽管它们的功能和具体的定位密切相关。在这里，我们报告了VTI12(ZIP1)中的一个新突变，它是ZIG-1的显性抑制因子。ZIP1突变通过改变SNARE复合体形成的特异性及其在细胞内的定位，使VTI12具有VTI11的功能。一种氨基酸替代显著改变了VTI12，使其能够抑制高阶生理功能的异常，如向重力性和形态。ZIP1突变可能表明了基因复制在植物细胞功能上的灵活性，特别是在VTI11基因及其最近分离的同源基因之间。
In higher multicellular eukaryotes, highly specialized membrane structures or membrane trafficking events are required for supporting various physiological functions. SNAREs (soluble NSF attachment protein receptors) play an important role in specific membrane fusions. These protein receptors are assigned to subgroubs (Qa-, Qb-, Qc-, and R-SNARE) according to their specific SNARE structural motif. A specific set of Qa-, Qb-, and Qc-SNAREs, located on the target membrane, interact with R-SNARE on the vesicle to form a tight complex, leading to membrane fusion [1-4]. The zig-1 mutant of Arabidopsis lacking Qb-SNARE VTI11 shows little shoot gravitropism and abnormal stem morphology. VTI11 and its homolog VTI12 exhibit partially overlapping but distinct intracellular localization and have different biological functions in plants [5-10]. Little is known about how SNAREs are targeted to specific organelles, even though their functions and specific localization are closely linked. Here, we report that a novel mutation in VTI12 (zip1) was found as a dominant suppressor of zig-1. The zip1 mutation gave VTI12 the ability to function as VTI11 by changing both the specificity of SNARE complex formation and its intracellular localization. One amino acid substitution drastically altered VTI12, allowing it to suppress abnormalities of higher order physiological functions such as gravitropism and morphology. The zip1 mutation may be an indication of the flexibility in plant cell function afforded by gene duplication, particularly among the VTI11 genes and their recently diverged orthologs.