Poster: Protein Targeting & Vesicular Trafficking
Abs #
1176: The rab GTPase, AtRabA4b, plays an important role during root hair tip-growth in Arabidopsis thaliana
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Presenter: |
Nielsen, Erik E, enielsen@danforthcenter.org |
Authors | Nielsen, Erik E (A) Mary, Preuss (A) Jannie, Santos-Serna (A) Aaron, Schmitz (A) | | Affiliations: |
(A): Donald Danforth Plant Science Center
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Spatial and temporal control of cell wall deposition plays unique and critical roles during plant growth and development. However, little is known about the molecular mechanisms by which cell wall polysaccharides are synthesized and secreted, or how polarized deposition occurs in differentiating plant cells. In order to identify endomembrane compartments involved in plant cell wall biogenesis, we have focused on Rab GTPases, a class of regulatory molecules that control membrane trafficking in eukaryotes. To this end, we have examined the function of one of these Rab GTPases, AtRabA4b, during polarized expansion in developing root hair cells. When AtRabA4b is fused with yellow fluorescent protein and expressed in A. thaliana, the resulting EYFP-AtRabA4b specifically localizes to the tips of growing root hair cells. Depolymerization of actin cytoskeletal elements with latrunculin B abolishes tip-localization of EYFP-AtRabA4b, and this correlates with inhibition of root hair expansion as determined by timelapse video microscopy. After latrunculin B washout, EYFP-AtRabA4b again becomes tip-localized, and root hair elongation resumes. Evidence that mutants with defects in root hair development exhibit aberrant localization of EYFP-AtRabA4b further supports a role for EYFP-AtRabA4b in proper root hair expansion. Our current hypothesis is that AtRabA4b localizes to a post-Golgi compartment involved in the polarized deposition of new cell wall during tip-growth in root hair cells. Subcellular localization of EYFP-AtRabA4b-labeled compartments in relation to other markers will be presented. Further, AtRabA4b-interacting proteins identified in a yeast two-hybrid screen will be described.
