Comparative Characterization of Phosphatidic Acid Sensors and Their Localization during Frustrated Phagocytosis

Nawal Kassas,Emeline Tanguy,Tamou Thahouly,Laetitia Fouillen,Dimitri Heintz,Sylvette Chasserot-Golaz,Marie-France Bader,Nancy J Grant,Nicolas Vitale

doi:10.1074/jbc.m116.742346

Abstract

Phosphatidic acid (PA) is the simplest phospholipid naturally existing in living organisms, but it constitutes only a minor fraction of total cell lipids. PA has attracted considerable attention because it is a phospholipid precursor, a lipid second messenger, and a modulator of membrane shape, and it has thus been proposed to play key cellular functions. The dynamics of PA in cells and in subcellular compartments, however, remains an open question. The recent generation of fluorescent probes for PA, by fusing GFP to PA-binding domains, has provided direct evidence for PA dynamics in different intracellular compartments. Here, three PA sensors were characterized in vitro, and their preferences for different PA species in particular lipidic environments were compared. In addition, the localization of PA in macrophages during frustrated phagocytosis was examined using these PA sensors and was combined with a lipidomic analysis of PA in intracellular compartments. The results indicate that the PA sensors display some preferences for specific PA species, depending on the lipid environment, and the localization study in macrophages revealed the complexity of intracellular PA dynamics.

Highlights

Phosphatidic acid (PA) is the simplest phospholipid naturally existing in living organisms, but it constitutes only a minor fraction of total cell lipids
The results indicate that the PA sensors display some preferences for specific PA species, depending on the lipid environment, and the localization study in macrophages revealed the complexity of intracellular PA dynamics
PA-binding domains (PABD) of Spo20p, Opi1p, and PDE4A1 Preferentially Bind to PA—In the attempt to characterize and compare biosensors for PA, we prepared GST fusion proteins composed of the PABD of Spo20p, Opi1p, and PDE4A1

Summary

Introduction

Phosphatidic acid (PA) is the simplest phospholipid naturally existing in living organisms, but it constitutes only a minor fraction of total cell lipids. The results indicate that the PA sensors display some preferences for specific PA species, depending on the lipid environment, and the localization study in macrophages revealed the complexity of intracellular PA dynamics. Phosphatidic acid (PA) has emerged as a new class of lipid mediators involved in diverse cellular functions through either structural or signaling modes of action. PA has been found to interact with or regulate at least 50 different partners present in all organisms from yeasts and plants to mammals [4] These include GTPases, kinases, phosphatases, nucleotide-binding proteins, and phospholipases [4]. In analogy with other lipid-signaling reactions, the interaction of proteins with PA often triggers their translocation from the cytosol to a specific membrane sub-compartment. PA can regulate small GTPases by modulating their regulatory proteins, guanine nucleotide exchange factors, and GTPase-activating proteins

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Conclusion