期刊
JOURNAL OF CELL SCIENCE
卷 122, 期 23, 页码 4383-4392出版社
COMPANY BIOLOGISTS LTD
DOI: 10.1242/jcs.053488
关键词
Ypt2; MG132; Proteasome; Root hair; PtdIns(4,5)P-2; Secretion; MORN domain
类别
资金
- Biotechnology and Biological Sciences Research Council [BBS/B/09562]
- Funda ao Ciencia e Tecnologia (FCT), Lisbon, Portugal [PPCDT/BIA-BCM/55700/2004, SFRH/BPD/20815/2004]
- Fundação para a Ciência e a Tecnologia [SFRH/BPD/20815/2004] Funding Source: FCT
- Biotechnology and Biological Sciences Research Council [REI20537, BBS/B/09562] Funding Source: researchfish
Rab GTPases of the Arabidopsis Rab-E subclass are related to mammalian Rab8 and are implicated in membrane trafficking from the Golgi to the plasma membrane. Using a yeast two-hybrid assay, Arabidopsis phosphatidylinositol-4-phosphate 5-kinase 2 (PtdIns(4)P 5-kinase 2; also known as PIP5K2), was shown to interact with all five members of the Rab-E subclass but not with other Rab subclasses residing at the Golgi or trans-Golgi network. Interactions in yeast and in vitro were strongest with RAB-E1d[Q74L] and weakest with the RAB-E1d[S29N] suggesting that PIP5K2 interacts with the GTP-bound form. PIP5K2 exhibited kinase activity towards phosphatidylinositol phosphates with a free 5-hydroxyl group, consistent with PtdIns(4)P 5-kinase activity and this activity was stimulated by Rab binding. Rab-E proteins interacted with PIP5K2 via its membrane occupancy and recognition nexus (MORN) domain which is missing from animal and fungal PtdIns(4)P 5-kinases. In plant cells, GFP:PIP5K2 accumulated at the plasma membrane and caused YFP:RAB-E1d to relocate there from its usual position at the Golgi. GFP:PIP5K2 was rapidly turned over by proteasomal activity in planta, and overexpression of YFP:PIP5K2 caused pleiotropic growth abnormalities in transgenic Arabidopsis. We propose that plant cells exhibit a novel interaction in which PIP5K2 binds GTP-bound Rab-E proteins, which may stimulate temporally or spatially localized PtdIns(4,5)P-2 production at the plasma membrane.
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