Functions and Mechanisms of SAC Phosphoinositide Phosphatases in Plants.

Yanbo Mao,Shutang Tan

doi:10.3389/fpls.2021.803635

Abstract

Phosphatidylinositol (PtdIns) is one type of phospholipid comprising an inositol head group and two fatty acid chains covalently linked to the diacylglycerol group. In addition to their roles as compositions of cell membranes, phosphorylated PtdIns derivatives, termed phosphoinositides, execute a wide range of regulatory functions. PtdIns can be phosphorylated by various lipid kinases at 3-, 4- and/or 5- hydroxyls of the inositol ring, and the phosphorylated forms, including PtdIns3P, PtdIns4P, PtdIns5P, PtdIns(3,5)P2, PtdIns(4,5)P2, can be reversibly dephosphorylated by distinct lipid phosphatases. Amongst many other types, the SUPPRESSOR OF ACTIN (SAC) family of phosphoinositide phosphatases recently emerged as important regulators in multiple growth and developmental processes in plants. Here, we review recent advances on the biological functions, cellular activities, and molecular mechanisms of SAC domain-containing phosphoinositide phosphatases in plants. With a focus on those studies in the model plant Arabidopsis thaliana together with progresses in other plants, we highlight the important roles of subcellular localizations and substrate preferences of various SAC isoforms in their functions.

Highlights

The biological membrane doesn’t only separate the cell from the outer environment, and defines specific territory for subcellular compartments
Despite representing a small fraction of total phospholipids, these negatively charged phosphoinositides play a vital role in various cellular activities, including membrane trafficking and cellular dynamics (Gerth et al, 2017; Noack and Jaillais, 2020)
In Arabidopsis, AtSAC6/7/8 targeted to the endoplasmic reticulum (ER) compartment when expressed in tobacco BY2 cells together with a C-terminally fused GFP (Despres et al, 2003), and they are required for both the maintenance of PtdIns(4,5)P2 polarity and the restriction of PtdIns4P at plasma membrane (PM) in root hairs (Thole et al, 2008; Song et al, 2021)

Summary

Introduction

The biological membrane doesn’t only separate the cell from the outer environment, and defines specific territory for subcellular compartments. The close related homolog OsGH1 dephosphorylated PtdIns4P and PtdIns(4,5)P2 from both in vitro phosphatase activity assay and binding studies.

Results

Conclusion