Shot-Gun Proteomic Analysis on Roots of Arabidopsis <em>pld&alpha;1</em> Mutants Suggesting New Roles of PLD&alpha;1 in Mitochondrial Protein Import, Vesicular Trafficking and Glucosinolate Biosynthesis

Abstract

Phospholipase D&amp;alpha;1 (PLD&amp;alpha;1) belongs to phospholipases, a large phospholipid hydrolyzing protein family. PLD&amp;alpha;1 has a substrate preference for phosphatidylcholine leading to enzymatic production of phosphatidic acid, a lipid second messenger with multiple cellular functions. PLD&amp;alpha;1 itself is implicated in biotic and abiotic stress responses. We present here a shot-gun differential proteomic analysis on roots of two pld&amp;alpha;1 mutants compared to the Col-0 wild type. Our data suggest new roles of PLD&amp;alpha;1 in endomembrane transport, mitochondrial protein import and protein quality control and glucosinolate biosynthesis. Thus, we identified proteins involved in endocytosis, endoplasmic reticulum-Golgi transport and attachment sites of endoplasmic reticulum and plasma membrane (V-type proton ATPases, protein transport protein SEC13 homolog A, vesicle-associated protein 1-2, vacuolar protein sorting-associated protein 29, syntaxin-32, all upregulated in the mutants), mitochondrial import and electron transport chain (mitochondrial import inner membrane translocase subunits TIM23-2 and TIM13, mitochondrial NADH dehydrogenases, ATP synthases, cytochrome c oxidase subunit 6b-1, ADP,ATP carrier protein 2, downregulated in the mutants) and glucosinolate biosynthesis (3-isopropylmalate dehydrogenases 1, 2 and 3, methylthioalkylmalate synthase 1, cytochrome P450 83B1, Glutathione S-transferase F9, indole glucosinolate O-methyltransferase 1, adenylyl-sulfate kinase 1, all upregulated in mutants). Our results suggest broader biological roles of PLD&amp;alpha;1 as anticipated so far.