New functions of plastoglobules in Vitamin E and K metabolism
| Responsable du projet | Félix Kessler |
| Collaborateur | Celine Besagni |
| Résumé |
Vitamins E and K are important components of nutrition and essential
for human health. Vitamin E (tocopherol group) consists of closely
related lipid-soluble antioxidants. They inhibit reactive oxygen
species production due to lipid peroxidation. Vitamin K
(phyllo-/menaquinone group) are lipid-soluble compounds that are
necessary for modification of proteins implicated in blood
coagulation. Together with plastoquinone, Vitamins E and K belong
to the family of prenylquinone compounds. In plants, these are
synthesized mostly in the chloroplast and carry important roles as
lipid antioxidants (tocopherol) and/or electron carriers in
photosynthesis (phylloquinone and plastoquinone), respectively. The
photosynthetic light reactions in the chloroplast take place at the
thylakoid membrane and this is where the prenylquinones fulfill
most of their essential roles in plants. In contrast, most of the
biosynthetic reactions take place in the envelope membranes. But we
recently discovered that chloroplast lipid droplets called
plastglobules that tightly associate with the thylakoid membrane
also play an essential role in prenylquinone metabolism. Using a
proteomics approach we identified about 30 different proteins
coating plastoglobules. These ranged from the structural
plastoglobulins, to a number of known enzymes (including the
tocopherol cyclase VTE1 required for tocopherol biosynthesis) as
well as uncharacterized proteins mostly predicted to be involved in
lipid metabolism. We therefore tested the hypothesis that
plastoglobules are indeed implicated in lipid and more specifically
in prenylquinone metabolism. Using state of the art lipidomics
techniques, among others, this lead to the discovery of essential
metabolic roles of plastoglobules in Vitamin E (tocopherol) and
Vitamin K (phylloquinone) accumulation. More important functions
certainly remain to be discovered. This project has three aims and
implicates a broad range of techniques: A) to systematically
unravel the function of several yet uncharacterized plastoglobule
proteins. These have hypothetical functions in the regulation of
prenylquinone synthesis and their trafficking between
plastoglobules and the thylakoid membrane. B) to adress the
hypothesis that plastoglobules are implicated in the biogenesis of
the thylakoid membrane early in seedling development. C) to
discover new genes that are required for correct plastoglobule
function and function. |
| Mots-clés |
metabolism, Lipids droplets, chloroplast, vitamin E, Vitamin K, lipidomic, plastoglobules |
| Type de projet | Recherche fondamentale |
| Domaine de recherche | Biologie cellulaire, cytologie |
| Source de financement | FNS - Encouragement de projets (Div. I-III) |
| Etat | Terminé |
| Début de projet | 1-8-2012 |
| Fin du projet | 31-7-2015 |
| Budget alloué | 244'027.00 |
| Autre information |
http://p3.snf.ch/projects-141229# |
| Contact | Félix Kessler |