Protein Targeting and Vesicular Trafficking
Phan, Nguyen , Bassham, Diane .
Functional investigation of two Arabidopsis sorting nexins.
Arabidopsis contains at least three sorting nexins, SNX1, SNX2a and SNX2b (Jaillais et al., 2006). Sorting nexins are PX domain-defined proteins that function in protein trafficking. The PX domain binds phosphatidylinositol phosphates and localizes the protein to specific membranes. Research in yeast showed that sorting nexins are important in the endosome-to-Golgi recycling pathway (Seaman, 2005). We have characterized Arabidopsis SNX2b and hypothesize that it is involved in trafficking to the plant vacuole. SNX2b protein is localized to the trans-Golgi network, prevacuolar compartment and endosomes. In vitro analysis has shown that it can selectively bind phosphatidylinositol 3-phosphate, and in vivo expression demonstrates that this binding is required for membrane association and correct subcellular localization. Overexpression of GFP-tagged SNX2b traps the endocytic marker, FM4-64, in GFP-labeled compartments, inhibiting further endocytic trafficking towards the vacuole. In addition, overexpression of SNX2b results in a partial inhibition of biosynthetic trafficking to the vacuole. Transgenic SNX2b RNAi lines show sensitivity to sucrose and salt stress, but do not have severe growth or developmental phenotypes. Functional redundancy between SNX2b and the closely related protein SNX2a may explain the relatively mild phenotype. We are examining double mutants to study the potential functions of SNX2a and SNX2b proteins.
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1 - Iowa State University, Interdepartmental Genetcs, 253 Bessey Hall, Ames, IA, 50010, USA
2 - Iowa State University, Genetics Development and Cell Biology Dept., 253 Bessey Hall, Ames, IA, 50010, USA
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM