Im, Yang Ju , Perera, Imara , Brglez, Irena , Davis, Amanda J , Stevenson-Paulik, Jill , Phillippy, Brian , Johannes, Eva , Allen, Nina , Boss, Wendy .
The impact of increasing plasma membrane Phosphatidylinositol(4,5)Bisphosphate on phosphoinositide turnover and cellular metabolism.
In response to many stimuli, plants produce a rapid and transient increase in PtdInsP2 and InsP3. This transient signal is thought to be part of a “wake up call”. Our hypothesis is that the plant phosphatidylinositol phosphate (PtdInsP) kinase (PIPK) is flux limiting in the phosphoinositide (PI) pathway. In an attempt to increase the capacity of the InsP3 signaling pool, we used a genetic approach expressing PIPK to phosphorylate PtdIns4P and produce phosphatidylinositol(4,5)bisphosphate (PtdIns(4,5)P2) which should in theory increase the production of InsP3, and alter the chemistry of the cell. Expressing the human PIPKIÎ± (HsPIPKIÎ±) in tobacco (Nicotianum tabacum) cells increased the plasma membrane PtdIns(4,5)P2 100 fold (from approximately 10 to 1,000 pmol/mg protein). In vivo studies revealed that the rate of incorporation of 32Pi into whole cell PtdIns(4,5)P2 increased more than 12 fold, and the ratio of [3H]PtdInsP2 to [3H]PtdInsP increased 6 fold. In addition, the basal Ins(1,4,5)P3 levels were >40-fold higher in the transgenic tobacco lines; however, even with this high steady state level of Ins(1,4,5)P3, the pathway was not saturated as stimulating the transgenic cells with hyperosmotic stress led to another 2-fold increase. Increasing the flux through the plant PI pathway by expressing HsPIPKIÎ± also lead to increased sugar utilization and oxygen uptake. Our results show that plant PIPK is flux limiting and demonstrate that constituvely increasing PtdIns(4,5)P2 biosynthesis and plasma membrane PI signaling increased the energy demands of the transgenic cells.
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Wendy Boss Lab
1 - North Carolina State University, Plant Biology, 2115 Gardner Hall, Campus Box 7612, Raleigh, NC, 27695, USA
2 - North Carolina State University, Plant Biology
3 - BASF Plant Science
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM