Minisymposium 6: Intercellular Signaling
Abs #
16004: Regulation of Non-Cell-Autonomous Protein Trafficking Pathways: I. Biochemical Studies
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Presenter: |
Lee, Jung-Youn , jynlee@ucdavis.edu |
Authors | Lee, Jung-Youn (A) Yoo, Byung-Chun (A) Taoka, Ken-ichiro (A) Lucas, William J (A) | | Affiliations: |
(A): University of California, Davis
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In plants, intercellular communication is mediated by the trafficking of information macromolecules that pass through unique cytoplasmic channels, called plasmodesmata. Molecular composition and the mechanism underlying this fundamental process are currently being elucidated [Lee, J.-Y. et al., Science 299, 392 (2003)]. Phosphorylation appears to play a role in controlling this cell-to-cell communication pathway [Lee, J.-Y. and Lucas, W. Trends Microbiol. 9, 5 (2001)]. To further characterize the role of phosphorylation in this process, we have purified, from plasmodesmal-enriched cell wall proteins, a protein kinase (PK) that phosphorylates tobacco mosaic virus movement protein (TMV MP). This PK, named NP3 for Non-cell-autonomous Protein Pathway3, phosphorylated specifically the C-terminal domain of the TMV MP. Furthermore, in vitro phosphorylation experiments demonstrated that NP3 has broad substrate specificity towards non-cell-autonomously acting endogenous and viral proteins (NCAPs). In an effort to take advantage of Arabidopsis genomic resources in studying NP3 gene family, full-length cDNAs encoding Arabidopsis homologues of NP3 (NP3-like protein kinases [NP3-LPK]) were isolated and corresponding GFP-fusion constructs were generated in both N- and C-terminal configurations. The intracellular localization of these NP3-LPK family members, studied by employing transient expression assays in BY-2 cells, will be discussed. We are also currently investigating the effects of phosphorylation on the functions performed by these target proteins, including changes in intracellular localization and capacity to traffic cell to cell. These studies will provide knowledge on the mechanism(s) by which plants regulate the movement of NCAPs which likely will yield insight into the manner in which plants evolved the capacity to control pathogen infection and orchestrate plant development.
