Unable to connect to database - 00:34:38 Unable to connect to database - 00:34:38 SQL Statement is null or not a SELECT - 00:34:38 SQL Statement is null or not a DELETE - 00:34:38 Botany & Plant Biology 2007 - Abstract Search
Unable to connect to database - 00:34:38 Unable to connect to database - 00:34:38 SQL Statement is null or not a SELECT - 00:34:38

Abstract Detail


Cell Walls

Kang, Byung-Ho [1], Preuss, Mary [2], Mastronarde, David [3], Cavalier, David [4], Staehelin, L. Andrew [5], Nielsen, Erik [2].

RabA4b and its effector PI-4Kβ are key components for regulating secretory vesicle size in Arabidopsis.

Non-cellulosic polysaccharides of plants are synthesized in the Golgi/trans-Golgi network (TGN) complex and delivered to the cell wall by secretory vesicles (SVs). The SVs bud from the TGN cisternae that arise and shed from the trans-Golgi cisternae. We have investigated the process of SV formation in high-pressure frozen/freeze-substituted root meristem cells of wild-type and of T-DNA inserted mutant Arabidopsis by means of electron tomography, immuno-electron tomography, and biochemical analyses. The first SVs arise at the periphery of trans-Golgi cisternae as they begin to separate from the Golgi stack and are transformed into TGN cisternae. Each TGN cisterna then converts into a cluster of budding secretory (55~100 nm in diameter) and clathrin coated (CCVs, 28~37 nm in diameter) vesicles, that are released during cisternal fragmentation. In root meristem cells, the formation of SVs consumes ~15X the amount of TGN membrane than the formation of CCVs. RabA4b is an Arabidopsis small GTPase that localizes specifically to SV budding sites in the TGN and cofractionates with cell wall polysaccharides. Phosphatidylinositol-4-kinase β (PI-4Kβ), a protein that interacts directly with activated AtRabA4b localizes also to the SVs of the TGN. Disruption of the PI-4Kβ genes causes a delay in TGN release, swelling of TGN cisternae, formation of very large secretory vesicles, and perturbation of cell plate assembly. However, the composition of the cell walls of the mutants is unchanged as determined by gas chromatography, and the number of CCVs produced by the mutant TGN was also unaltered. Our data demonstrate that RabA4b and its effector PI-4Kβ are involved in secretory vesicle formation and play a key role in determining the size of the SVs that bud from the TGN cisternae.
Supported by NIH grant MG61306 to LAS.


Log in to add this item to your schedule

1 - University of Colorado at Boulder, Molecular, Cellular, and Developmental Biology Department, UCB 347 MCD Biology University of Colorado at Boulder, Boulder, CO, 80309, USA
2 - Donald Danforth Plant Science Center
3 - University of Colorado at Boulder, Boulder Laboratory for 3D Electron Microscopy of Cells
4 - Michigan State University, MSU-DOE Plant Research Lab
5 - University of Colorado at Boulder, Molecular, Cellular, and Developmental Biology Department

Keywords:
Golgi
secretory vesicle
cell wall
polysaccharide.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P17010
Abstract ID:363


Copyright 2000-2007, Botanical Society of America. All rights