Arabidopsis Rab-E GTPases exhibit a novel interaction with a plasma-membrane phosphatidylinositol-4-phosphate 5-kinase.

Journal article

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.

Authors: Camacho, L; Smertenko, A; Pérez-Gómez, J; Hussey, P; Moore, I

• Publication status: Published
• Journal: Journal of cell science
• Volume: 122
• Issue: Pt 23
• Pages: 4383-4392
• Publication date: 2009-12-01
• DOI: 10.1242/jcs.053488
• EISSN: 1477-9137
• ISSN: 0021-9533
• Language: English
• Keywords: Plant Leaves; Cell Membrane; rab GTP-Binding Proteins; Phosphotransferases (Alcohol Group Acceptor); Point Mutation; Protein Binding; Plants, Genetically Modified; Tobacco; Arabidopsis Proteins; Two-Hybrid System Techniques