Ben-Nissan, Gili , Lee, Jung-Youn .
Targeting of PAPK1 Involves Association with Cytoskeleton
and Vesicle-like Organelles.
Accumulating evidence supports that plasmodesmata play fundamental roles in plants, however, it is not well understood how plasmodesmal function is regulated at the molecular level. Recent isolation and characterization of Plasmodesmal-associated Protein Kinase 1 (PAPK1) as a kinase capable of phosphorylating a subset of non-cell autonomous proteins suggested that protein phosphorylation might be one potential regulatory mechanism [Lee et al., Plant Cell 17, 2817 (2005)]. To further elucidate how PAPK1 targeting to plasmodesmata is achieved, we have performed a series of molecular and cell biological analyses. Fluorescently-tagged PAPK1 was localized to highly motile vesicle-like organelles (VLOs) both in the cytoplasm and at the cell periphery. Upon plasmolysis, some VLOs were found at the cross wall regions in a close association with plasmodesmata. Deletion mutagenesis demonstrated that neither the catalytic domain nor the CTD alone was sufficient for the correct targeting of PAPK1 to VLOs. Further analyses suggested that the CTD contained a novel microtubule association domain, and the coordination between active catalytic domain and the CTD is indispensable for the PAPK1 targeting. In order to gain insight into the nature of the PAPK1-labelled VLOs, we are currently carrying out co-localization studies with various endosomal markers as well as immunogold labeling of endogenous PAPK1. The data will be discussed in the context of a model that interactions with vesicles and cytoskeleton might be one potential mechanism underlying the PAPK1 targeting to the subcellular structures and plasmodesmata.
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Lab Web Site
1 - Delaware Biotechnology Institute and University of Delaware, Plant and Soil Sciences
2 - Delaware Biotechnology Institute and University of Delaware, Plant and Soil Sciences, 15 Innovation Way, Newark, DE, 19711, USA
Presentation Type: ASPB Minisymposium
Location: Continental B/Hilton
Date: Wednesday, July 11th, 2007
Time: 11:05 AM