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Regulatory Functions of Phospholipase D and Phosphatidic Acid in Plant Growth, Development, and Stress Responses

Xuemin Wang

Published October 2005. DOI: https://doi.org/10.1104/pp.105.068809

Article Figures & Data

Figures

  • Figure 1.
    Figure 1.

    PLD-catalyzed hydrolysis of phospholipids, downstream targets, and cellular functions. The activity of PLD produces PA and free-head group (X). PA target proteins have been identified in animals, plants, and yeast (see also Table I). Multiple cellular effects of PLD and PA have been documented or implicated. Note that in addition to PLD, signaling PA can be generated from DAG kinase coupled to the activation of PLC and potentially from acylation reactions.

  • Figure 2.
    Figure 2.

    Domain structures of Arabidopsis PLDs. Plant PLDs consist of two distinctive subfamilies: the C2-PLDs and the PX/PH-PLDs. Individual PLDs can differ in key amino acid residues in regulatory motifs, such as C2, PIP2 binding, and DRY. The duplicated HKD motifs are involved in catalysis. Note that the 12 Arabidopsis PLDs have now been classified into six types instead of five types; the only modification is that PLDα4 has been reclassified to PLDε because this PLD is quite distant from all the other PLDs.

  • Figure 3.
    Figure 3.

    A working model depicting the activation of PLDs and the role of PA in regulating kinase and phosphatase activities in cell's response to ABA, H2O2, or other stimuli. Potential mediators in the PLD activation include changes in G protein function and membrane conformations and/or increases in cytosolic Ca2+, phopshoinositides, and oleic acid. PLD-produced PA may stimulate protein kinase cascades and also inhibit protein phosphatases. PA may do so by directly affecting the enzymatic activities and/or by tethering the signaling enzymes to specific membranes or regions of a membrane. These interactions modulate the cell's ability to respond to stresses and inhibit cell death.

  • Figure 4.
    Figure 4.

    Unique roles of different PLDs, multifaceted functions of a PLD, and multiple modes of action of PA. Unique functions have been shown for PLDα1 and PLDδ. Box 1 lists some of the available findings that support different functions of PLDs. Box 2 indicates that a given PLD can be involved in different cellular processes, depending upon the nature of biotic and abiotic cues, such as the severity of stresses. Box 3 lists several effects that PA has on cell regulation. Documented examples are given in parentheses, and those in bold denote PA target proteins identified in plants. The symbol and function of the target proteins are explained in Table I and text. FFA, Free fatty acid; DAG-PPi, DAG-pyrophosphate.

Tables

  • Table I.

    Examples of PA-binding proteins identified in plants, animals, and yeast

    PA-Binding ProteinProtein FunctionReference
    From plants:
    ABI1Protein phosphatase 2C likeZhang et al. (2004)
    AtPDK13′-Phopshoinositide-dependent kinase 1Anthony et al. (2004)
    PEPCPhosphoenolpyruvate carboxylaseTesterink et al. (2004)a
    From yeast:
    Opi1pSoluble transcriptional repressorLoewen et al. (2004)
    From animals:
    mTORMammalian target of rapamycinFang et al. (2001)
    Raf1MAP kinase kinase kinaseGhosh et al. (2003)
    FgrTyr kinases expressed in neutrophilsSergeant et al. (2001)
    PKCzProtein kinase CζCummings et al. (2002)
    SHP-1SH2-containing protein-tyrosine phosphataseFrank et al. (1999)
    PP1Protein phosphatase-1Jones and Hannun (2002)
    Type1 PI4P5KPhosphatidylinositol 4P-5 kinaseJenkins et al. (1994)
    RGS4Regulators of G-protein signaling proteinOuyang et al. (2003)
    SPHKSphingosine kinaseDelon et al. (2004)
    ARFADP-ribosylation factorManifava et al. (2001)
    NSFN-ethylmaleimide-sensitive factor
    KinesinVesicular trafficking
    Phox 47A cytosolic component of NADPH oxidaseKarathanassis et al. (2002)
    PDE4D3cAMP-specific phosphodiesteraseGrange et al. (2000)

    • ↵a Several other proteins were also found to be associated with PA-affinity beads.

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Regulatory Functions of Phospholipase D and Phosphatidic Acid in Plant Growth, Development, and Stress Responses
Xuemin Wang
Plant Physiology Oct 2005, 139 (2) 566-573; DOI: 10.1104/pp.105.068809
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