Botany and Plant Pathology Seminar Series
Speaker: Dr. Aaron Smith - Department of Biological Sciences - Louisiana State University
Topic: Probing the phosphate and arsenate activities of plant high affinity phosphate transporters
When: Wednesday, December 11, 2013 at 3:30 pm in WSLR 116

Currently, agricultural crop production worldwide suffers from phosphorus-deficient and arsenic-contaminated soils. Many plant high-affinity phosphate transporters (PHTs), which acquire phosphate and arsenate from soil, have been described, but little is known regarding the biochemical properties that contribute to their activities.  Using split-luciferase and split-ubiquitin complementation assays, we have shown that two Arabidopsis thaliana PHT proteins, PHT1 and PHT4, form hetero- and homo-oligomers.  In addition, we characterized several site-directed mutants of PHT1, and identified a single amino acid essential for oligomerization.  Analysis of these mutants also revealed that the ability to form higher order structures is not required for transport activity in yeast.  Indeed, a variety of PHT1 mutants that were shown to have diminished oligomerization potential were able to transport both phosphate and arsenate as observed in growth assays of yeast cells expressing the mutants.  We have used this yeast expression system to also characterize novel PHTs from the arsenic hyperaccumulating fern, Pteris vittata.  One of these PHTs was shown to have a phosphate transport activity similar to PHTs from Arabidopsis, but an enhanced ability to transport arsenate.  Insight gained from these studies will lead to a better understanding of PHT transport of phosphate and arsenate, and ultimately to improvements in agricultural and phytoremediation practices.

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