VND-INTERACTING2, a NAC Domain Transcription Factor, Negatively Regulates Xylem Vessel Formation in Arabidopsis
VND-INTERACTING2, a NAC Domain Transcription Factor, Negatively Regulates Xylem Vessel Formation in Arabidopsis
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DOI：
10.1105/tpc.108.064048
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发表时间：
2010-04-01
期刊：
影响因子：
11.6
通讯作者：
Demura, Taku
中科院分区：
文献类型：
--
作者：
Yamaguchi, Masatoshi;Ohtani, Misato;Demura, Taku
拟南芥NAC结构域转录因子VEC-DOMAIN7(VND7)是木质部导管分化的主要调控因子。为了了解VND7调节木质部导管分化的机制，我们使用酵母双杂交系统筛选与VND7相互作用的蛋白，并鉴定了编码两个NAC结构域蛋白的cDNA，VND-InterACTING1(VNI1)和VNI2。结合分析表明，VNI2与VND7和VND家族蛋白VND1-5以及其他NAC结构域蛋白以较低的亲和力相互作用。VNI2在根和花序茎的木质部和韧皮部细胞中均有表达。在根中，VNI2和VND7在伸长的血管前体中的表达重叠。VNI2含有一个预测的PEST基序，C端截短的VNI2蛋白比全长的VNI2蛋白更稳定，它缺乏部分PEST基序。瞬时报告分析表明，VNI2是一个转录抑制因子，可以抑制受VND7调控的血管特异基因的表达。在VND7启动子的控制下，C端截短的VNI2的表达抑制了根和地上器官木质部导管的正常发育。这些数据表明，VNI2作为转录抑制因子调节木质部细胞的特性，与VND蛋白相互作用，也可能与其他NAC结构域蛋白相互作用。
The Arabidopsis thaliana NAC domain transcription factor VASCULAR-RELATED NAC-DOMAIN7 (VND7) acts as a master regulator of xylem vessel differentiation. To understand the mechanism by which VND7 regulates xylem vessel differentiation, we used a yeast two-hybrid system to screen for proteins that interact with VND7 and identified cDNAs encoding two NAC domain proteins, VND-INTERACTING1 (VNI1) and VNI2. Binding assays demonstrated that VNI2 effectively interacts with VND7 and the VND family proteins, VND1-5, as well as with other NAC domain proteins at lower affinity. VNI2 is expressed in both xylem and phloem cells in roots and inflorescence stems. The expression of VNI2 overlaps with that of VND7 in elongating vessel precursors in roots. VNI2 contains a predicted PEST motif and a C-terminally truncated VNI2 protein, which lacks part of the PEST motif, is more stable than full-length VNI2. Transient reporter assays showed that VNI2 is a transcriptional repressor and can repress the expression of vessel-specific genes regulated by VND7. Expression of C-terminally truncated VNI2 under the control of the VND7 promoter inhibited the normal development of xylem vessels in roots and aerial organs. These data suggest that VNI2 regulates xylem cell specification as a transcriptional repressor that interacts with VND proteins and possibly also with other NAC domain proteins.