A small plant-specific protein family of ABI five binding proteins (AFPs) regulates stress response in germinating Arabidopsis seeds and seedlings
A small plant-specific protein family of ABI five binding proteins (AFPs) regulates stress response in germinating Arabidopsis seeds and seedlings
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DOI：
10.1007/s11103-008-9344-2
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发表时间：
2008-08-01
影响因子：
5.1
通讯作者：
Finkelstein, Ruth
中科院分区：
文献类型：
--
作者：
Garcia, Mary Emily;Lynch, Tim;Finkelstein, Ruth
转录因子ABA-Insensitive 5（ABI 5）是拟南芥种子和幼苗中阿坝信号和胁迫反应的关键调节因子。通过酵母双杂交筛选鉴定了潜在的ABI 5相互作用蛋白;最普遍的相互作用物是一个由四种高度保守的植物特异性蛋白组成的家族，其没有已知功能的结构域，但与先前表征的ABI Five结合蛋白（AFP）同源。本研究比较了家族成员的表达和功能。AFPs诱导阿坝和/或脱水胁迫在幼苗，但其诱导的发育时间不同。AFP 1或AFP 2的突变导致对阿坝和盐的敏感性增加，而afp 4突变体是温和的ABA抗性。AFP 2与AFP 1一样，对ABI 5起上位性作用。与野生型幼苗相比，胁迫下突变体的发芽或幼苗生长减少与ABI 5蛋白水平较高相关，但尚不清楚这是否是生长减少的原因或影响。虽然ABI 5和AFP都是ABA诱导的，但ABI 5：AFP比率在高阿坝浓度下增加，在严重胁迫下维持生长抑制。AFP 2：GFP融合，补充afp 2突变，是核本地化的幼苗暴露于压力，但成为离域之前，被降解后的应力去除。AFP还可以与许多ABI 5相关的bZIP转录因子在不同程度上相互作用。这项研究表明，发芽和幼苗生长调节至少两个功能冗余的家庭，AFP和ABI 5相关蛋白之间的拮抗作用，提供了一种机制，微调幼苗胁迫反应。
The transcription factor ABA-Insensitive5 (ABI5) is a key regulator of ABA signaling and stress response in Arabidopsis seeds and seedlings. Potential ABI5-interacting proteins were identified by a yeast two-hybrid screen; the most prevalent interactors were a family of four highly conserved plant-specific proteins with no domains of known function, but homology to a previously characterized ABI Five Binding Protein (AFP). This study compares expression and function of the family members. The AFPs are induced by ABA and/or dehydrating stresses in young seedlings, but the developmental timing of their induction differs. Mutations in AFP1 or AFP2 result in increased sensitivity to ABA and salt, whereas afp4 mutants are mildly ABA-resistant. AFP2, like AFP1, acts epistatically to ABI5. Reduced germination or seedling growth of the mutants under stress correlates with a higher level of ABI5 protein when compared to wild-type seedlings, but it is not clear whether this is a cause or effect of the reduced growth. Although both ABI5 and the AFPs are ABA-induced, the ABI5:AFP ratio increases at high ABA concentrations, maintaining growth inhibition under severe stress. An AFP2:GFP fusion, which complements the afp2 mutation, is nuclear-localized in seedlings exposed to stress, but becomes delocalized before being degraded following removal of stress. The AFPs may also interact to varying extents with many ABI5-related bZIP transcription factors. This study suggests that germination and seedling growth are regulated by antagonistic interactions among at least two functionally redundant families, the AFPs and the ABI5-related proteins, providing a mechanism to fine-tune seedling stress responses.