Involvement of BIG5 and BIG3 in BRI1 Trafficking Reveals Diverse Functions of BIG-subfamily ARF-GEFs in Plant Growth and Gravitropism
Involvement of BIG5 and BIG3 in BRI1 Trafficking Reveals Diverse Functions of BIG-subfamily ARF-GEFs in Plant Growth and Gravitropism
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DOI：
10.3390/ijms20092339
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发表时间：
2019-05-01
影响因子：
5.6
通讯作者：
Le, Jie
中科院分区：
文献类型：
--
作者：
Xue, Shan;Zou, Junjie;Le, Jie
ADP-核糖基化因子-鸟嘌呤核苷酸交换因子（ARF-GEFs）是真核生物中囊泡运输的关键调节因子。在拟南芥中，有八个ARF-GEF，包括三个GBF 1亚家族成员和五个BIG亚家族成员。这些ARF-GEFs具有不同的亚细胞定位，调节不同的运输途径。到目前为止，这些大亚家族的ARF-GEFs的作用尚未完全揭示。在此，对BIGs表达模式的分析显示BIG 3和BIG 5具有相似的表达模式。big 5 -1表现出矮化生长，而big 3 -1 big 5 -1双突变体表现出更严重的缺陷，表明BIG 3和BIG 5之间存在功能冗余。此外，big 5 -1和big 3 -1 big 5 -1均表现出对阿糖胞苷（BR）治疗的敏感性降低。在big 5 -1突变体中，布雷菲德菌素A（BFA）诱导的BR受体对维生素类固醇不敏感的1（BRI 1）聚集减少，表明BIG 5的作用是BRI 1再循环所必需的。此外，BR诱导的转录因子BZR 1的去磷酸化在big 3 -1 big 5 -1双突变体中减少。在big 3 -1 big 5 -1突变体中引入功能获得性BZR 1 -1D可以部分挽救big 3 -1 big 5 -1的生长缺陷。研究结果表明，BIG 5与BIG 3在植物生长和向地性中具有冗余功能，BIG 5通过调控BRI 1的运输参与BR信号转导途径。
ADP-ribosylation factor-guanine nucleotide exchange factors (ARF-GEFs) act as key regulators of vesicle trafficking in all eukaryotes. In Arabidopsis, there are eight ARF-GEFs, including three members of the GBF1 subfamily and five members of the BIG subfamily. These ARF-GEFs have different subcellular localizations and regulate different trafficking pathways. Until now, the roles of these BIG-subfamily ARF-GEFs have not been fully revealed. Here, analysis of the BIGs expression patterns showed that BIG3 and BIG5 have similar expression patterns. big5-1 displayed a dwarf growth and big3-1 big5-1 double mutant showed more severe defects, indicating functional redundancy between BIG3 and BIG5. Moreover, both big5-1 and big3-1 big5-1 exhibited a reduced sensitivity to Brassinosteroid (BR) treatment. Brefeldin A (BFA)-induced BR receptor Brassinosteroid insensitive 1 (BRI1) aggregation was reduced in big5-1 mutant, indicating that the action of BIG5 is required for BRI1 recycling. Furthermore, BR-induced dephosphorylation of transcription factor BZR1 was decreased in big3-1 big5-1 double mutants. The introduction of the gain-of-function of BZR1 mutant BZR1-1D in big3-1 big5-1 mutants can partially rescue the big3-1 big5-1 growth defects. Our findings revealed that BIG5 functions redundantly with BIG3 in plant growth and gravitropism, and BIG5 participates in BR signal transduction pathway through regulating BRI1 trafficking.