Regulation of ABA-Non-Activated SNF1-Related Protein Kinase 2 Signaling Pathways by Phosphatidic Acid.

Maria Klimecka,Justyna Maszkowska,Grażyna Goch,Grażyna Dobrowolska,Małgorzata Lichocka,Maria Bucholc,Ewa Krzywińska,Jadwiga Szczegielniak

doi:10.3390/ijms21144984

Abstract

Phosphatidic acid (PA) is involved in the regulation of plant growth and development, as well as responses to various environmental stimuli. Several PA targets in plant cells were identified, including two SNF1-related protein kinases 2 (SnRK2s), SnRK2.10 and SnRK2.4, which are not activated by abscisic acid (ABA). Here, we investigated the effects of PA on various elements of ABA-non-activated SnRK2 signaling. PA 16:0/18:1 was found to modulate the SnRK2 structure and the phosphorylation of some SnRK2 targets. Conversely, phosphorylation by the ABA-non-activated SnRK2s, of one of such targets, dehydrin Early Responsive to Dehydration 14 (ERD14), affects its interaction with PA and subcellular localization. Moreover, PA 16:0/18:1 modulates the activity and/or localization of negative regulators of the ABA-non-activated SnRK2s, not only of the ABA insensitive 1 (ABI1) phosphatase, which was identified earlier, but also of another protein phosphatase 2C, PP2CA. The activity of both phosphatases was inhibited by about 50% in the presence of 50 μM PA. PA 16:0/18:1 also impacts the phosphorylation and subcellular localization of SnRK2-interacting calcium sensor, known to inhibit SnRK2 activity in a calcium-dependent manner. Thus, PA was found to regulate ABA-non-activated SnRK2 signaling at several levels: the activity, phosphorylation status and/or localization of SnRK2 cellular partners.

Highlights

Phospholipids are the major components of cell membranes, but they act as second messengers involved in plant responses to a variety of stimuli, including biotic and abiotic stresses
It was established that two Arabidopsis thaliana kinases, SnRK2.4 and SnRK2.10, which belong to group 1 of the SnRK2 family (ABA-non activated kinases), interact with Phosphatidic acid (PA), whereas the abscisic acid (ABA)-activated kinase SnRK2.6 does not [19,34], suggesting that this interaction is specific for the SnRK2s that are not activated in response to ABA [21]
We tested the interaction of the phospholipids with two phosphatases from clade A of the Arabidopsis PP2C family, which are established to be negative regulators of the ABA-activated [67,68] and ABA-non-activated [69,70] SnRK2s, ABA insensitive 1 (ABI1) and PP2CA

Summary

Introduction

Phospholipids are the major components of cell membranes, but they act as second messengers involved in plant responses to a variety of stimuli, including biotic and abiotic stresses. PA can be generated via several distinct routes: via phospholipases D (PLD) which hydrolyze structural lipids to PA and a free head group, via a sequential action of phospholipases C (PLC) and diacylglycerol kinase (DAGK), and via de novo synthesis by lysophosphatidyl acyltransferases from the glycerol-3-phosphate (Gro3P) pathway-derived lysophosphatidic acid (LPA) (for reviews, see References [6,13,14]). Activation of these pathways determines the timing, localization, and accumulation of specific molecular species of PA. PA was shown to transmit signals by changing the localization of the target protein (in most cases, by recruiting it to membranes), by altering protein conformation, which can, e.g., modulate its enzymatic activity, and by affecting the curvature of membranes [6]

Methods

Results

Conclusion