Poster: Signaling, cell-to-cell

Abs # 426: Phosphatidic Acid as a Pivotal Lipid Messenger in Cell Signaling in Plants

Presenter:	Wang, Xuemin , wangs@ksu.edu
Authors	Wang, Xuemin  (A)   Zhang, Wenhua  (A)   Zhao, Jian  (A)   Devaiah, Shivakumar Pattada  (A)   Li, Weilqi  (A)   Li, Maoyin  (A)   Hong, Yueyun  (A)   Welti, Ruth  (B)
Affiliations:	(A): Department of Biochemistry, Kansas State University (B): Division of Biology, Kansas State University

Signal transduction and many other critical cellular functions are initiated by the assembly of protein complexes at specific sites on cellular membranes. Lipid binding is required for the recruitment and/or regulation of these proteins. Lipid mediators, such as phosphoinositides, are produced in response to specific stimuli and bind to effector proteins at structural folds, including pleckstrin homology (PH), Phox homology (PX), and FYVE domains. These specific lipid-protein interactions are critical for cellular activities of many proteins. Phosphatidic acid (PA) has recently emerged as an important lipid mediator in many cellular processes, including cell proliferation and survival, cell patterning and growth, and stress responses. However, the mechanism by which PA regulates cellular processes is not understood. We have obtained evidence that PA interacts directly with protein kinases and phosphatases. Our results indicate that PA regulates both the activity and intracellular distribution of its effector proteins. In addition, we have identified the protein motifs required for the PA-effector interaction. We have demonstrated the regulatory functions of PA by manipulating the PA-producing enzymes, phospholipase Ds (PLD), by lipid profiling, and by cellular/physiological analyses. These results unveil a complex signaling network in which PA and PLD interact with G protein, protein kinase, and protein phosphatase to mediate plant responses to hormones, reactive oxygen species, biotic and abiotic stresses. Supported by grants from NSF and USDA