The type B phosphatidylinositol-4-phosphate 5-kinase 3 is essential for root hair formation in Arabidopsis thaliana
The type B phosphatidylinositol-4-phosphate 5-kinase 3 is essential for root hair formation in Arabidopsis thaliana
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DOI：
10.1105/tpc.107.052852
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发表时间：
2008-01-01
期刊：
影响因子：
11.6
通讯作者：
Heilmann, Ingo
中科院分区：
文献类型：
--
作者：
Stenzel, Irene;Ischebeck, Till;Heilmann, Ingo
根毛是根表皮细胞的延伸，是植物细胞顶端定向生长的模型系统。一个以前未知的拟南芥磷脂酰肌醇-4-磷酸5-激酶基因（PIP 5 K3）被确定，并发现在根皮层，表皮细胞和根毛中表达。重组PIP 5 K3蛋白具有催化活性并将磷脂酰肌醇-4-磷酸转化为磷脂酰肌醇-4，5-二磷酸[PtdIns（4，5）P-2]。T-DNA破坏的PIP 5 K3等位基因纯合的拟南芥突变体植物在根毛形成方面受到损害，这是一种通过在1500 bp PIP 5 K3启动子片段的控制下表达野生型PIP 5 K3 cDNA来补充的表型。根毛特异性PIP 5 K3过表达导致根毛变形和细胞极性丧失，并增加PIP 5 K3转录物的积累。使用T-DNA突变体中根毛形成的重建作为工程化PIP 5 K3变体的生理功能的生物测定，发现催化活性对于生理功能是必需的，表明PtdIns（4，5）P-2形成是根毛发育所需的。一个N-末端结构域含有膜占领和识别连接重复，这是不需要的催化活性，被认为是必不可少的根毛生长的建立。标记的PIP 5 K3定位于根尖区的根毛细胞的周边，可能与质膜和/或胞吐囊泡。全长PIP 5 K3在烟草（Nicotiana tabacum）花粉管中的瞬时异源表达增加了这些尖端生长细胞中PtdIns（4，5）P-2特异性报告基因的质膜结合。数据表明，根毛发育需要在根毛细胞的顶端区域产生PIP 5 K3依赖性PtdIns（4，5）P-2。
Root hairs are extensions of root epidermal cells and a model system for directional tip growth of plant cells. A previously uncharacterized Arabidopsis thaliana phosphatidylinositol-4-phosphate 5-kinase gene (PIP5K3) was identified and found to be expressed in the root cortex, epidermal cells, and root hairs. Recombinant PIP5K3 protein was catalytically active and converted phosphatidylinositol-4-phosphate to phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P-2]. Arabidopsis mutant plants homozygous for T-DNA-disrupted PIP5K3 alleles were compromised in root hair formation, a phenotype complemented by expression of wild-type PIP5K3 cDNA under the control of a 1500-bp PIP5K3 promoter fragment. Root hair-specific PIP5K3 overexpression resulted in root hair deformation and loss of cell polarity with increasing accumulation of PIP5K3 transcript. Using reestablishment of root hair formation in T-DNA mutants as a bioassay for physiological functionality of engineered PIP5K3 variants, catalytic activity was found to be essential for physiological function, indicating that PtdIns(4,5)P-2 formation is required for root hair development. An N-terminal domain containing membrane occupation and recognition nexus repeats, which is not required for catalytic activity, was found to be essential for the establishment of root hair growth. Fluorescence-tagged PIP5K3 localized to the periphery of the apical region of root hair cells, possibly associating with the plasma membrane and/or exocytotic vesicles. Transient heterologous expression of full-length PIP5K3 in tobacco (Nicotiana tabacum) pollen tubes increased plasma membrane association of a PtdIns(4,5)P-2-specific reporter in these tip-growing cells. The data demonstrate that root hair development requires PIP5K3-dependent PtdIns(4,5)P-2 production in the apical region of root hair cells.