Poster: Vegetative development

Abs # 326: Developmental coordination of MVA and MEP isoprene pathways requires protein prenylation

Presenter:	Gruissem, Wilhelm , wilhelm.gruissem@ipw.biol.ethz.ch
Authors	Galichet, Arnaud  (A)   Fuerholz, Andreas  (A)   Laule, Oliver  (A)   Wille, Anja  (B) (C)  Buehlmann, Peter  (B) (C)  Beemster, Gerrit  (D)   Gruissem, Wilhelm  (A) (C)
Affiliations:	(A): Institute of Plant Sciences, Swiss Federal Institute of Technology (B): Seminar for Statistics, Swiss Federal Institute of Technology (C): Reverse Engineering Group, Swiss Federal Institute of Technology (D): Department of Plant Systems Biology, University of Gent, Belgium
Web Site:	http://www.pb.ethz.ch

In plants, isoprenes are synthesized by two independent pathways located in the cytoplasm (MVA-pathway) and the plastids (MEP-pathway). It is now generally accepted that crosstalk exist between the two pathways, but the mechanisms that coordinate the pathways and that control the bidirectional flow of intermediates during development are currently not well understood. We are using genetic, kinematic, RNA profiling and reverse engineering approaches to dissect the regulatory network that controls isoprene synthesis. As part of this effort we are also focusing on protein farnesyl transferase (PFT) and geranylgeranyl transferase (PGGT-I), which catalyze the addition of FPP and GGPP to a CaaX-box in the C-terminus of key regulatory proteins. We first investigated the regulatory network that controls both isoprenoid pathways in the context of seedling and leaf development. The Arabidopsis mutant era1-2 lacks protein farnesylation, and cla1 is a mutant of the gene for DXP, the first enzyme of the MEP-pathway. These mutants were compared to plants in which the MVA- or the MEP-pathway was blocked with statins or fosmidomycin. Gaussian graphical modeling revealed the existence of a gene network for isoprene biosynthesis. This gene network appears to be dependent on flux through the MVA-pathway and the availability of FPP. Reduction in MVA-pathway activity or loss of FPP-dependent protein prenylation affects flux from the MEP-pathway into the cytoplasm. Loss of FPP-dependent protein prenylation alone delays leaf maturation and allows reentry into a juvenile development program. Our results suggest that PFT-mediated prenylation is a key regulatory event in the crosstalk between MVA- and MEP-pathways and in the control of the gene network for isoprene biosynthesis in plants.