391 / 2019-02-19 23:07:02

Functional analysis of PI4Pkinase alpha1 in Arabidopsis

phosphoinositides,PI(4)P,pollen,plasma membrane,anionic lipids,vacuolar trafficking,EFR3,PI4-kinases,stt4

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Each cell is made of different compartments with its own membrane identity that allows proper localization of proteins. Phosphoinositol phosphates (PIPs) participate to the acquisition of this identity through their spatiotemporal enrichment in different compartments of the cell (1). In Arabidopsis thaliana, PI4P accumulates principally at the plasma membrane where it is responsible of its high negative charge facilitating electrostatic interactions with polybasic regions on proteins (2). The Arabidopsis genome encodes for three kinases able to produce PI4P: PI4Kα1, PI4Kβ1 and PI4Kβ2. As PI4Kβ1 and PI4Kβ2 localize to the Trans-Golgi Network/Early Endosomes (TGN/EE) (3,4), PI4Kα1 is a prime candidate for managing the production of PI4P at the plasma membrane.
Here, we characterized PI4Kα1 mutants and showed that pi4kα1 loss-of-function leads to pollen grain lethality and distortion in the allele transmission via the female gametophyte, while its knockdown displayed strong developmental phenotypes. In addition, we showed that PI4Kα1 proteins localized to the plasma membrane. Using yeast two hybrid screening, we identified that PI4Kα1 is part of an heterotetrameric complex. We discuss the potential role of this complex in regulating PI4Kα1 function and localization.

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