Tocopherol Cyclase (VTE1) Localization and Vitamin E Accumulation in Chloroplast Plastoglobule Lipoprotein Particles

doi:10.1074/jbc.M511939200

Tocopherol Cyclase (VTE1) Localization and Vitamin E Accumulation in Chloroplast Plastoglobule Lipoprotein Particles^*

^{^‡}Institute of Botany, University of Neuchâtel, Emile Argand 11, CH-2007 Neuchâtel, Switzerland, the ^{^§}Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476 Golm, Germany, the ^{^¶}Institute of Plant Sciences, Swiss Federal Institute of Technology, Universitätstrasse 2, CH-8092 Zurich, Switzerland, the ^{^∥}University of Chicago, Chicago, Illinois 60637, and the ^{^**}Institute of Biochemistry, Swiss Federal Institute of Technology, Schafmattstrasse 18, CH-8093 Zürich, Switzerland

1 To whom correspondence should be addressed: Laboratoire de Physiologie Végétale, Institut de Botanique, Université de Neuchâtel, Emile Argand 11, CH-2007 Neuchâtel, Switzerland. Tel.: 41-32-718-22-92; Fax: 41-32-718-22-71; E-mail: felix.kessler{at}unine.ch.

Abstract

Chloroplasts contain lipoprotein particles termed plastoglobules. Plastoglobules are generally believed to have little function beyond lipid storage. Here we report on the identification of plastoglobule proteins using mass spectrometry methods in Arabidopsis thaliana. We demonstrate specific plastoglobule association of members of the plastid lipid-associated proteins/fibrillin family as well as known metabolic enzymes, including the tocopherol cyclase (VTE1), a key enzyme of tocopherol (vitamin E) synthesis. Moreover, comparative analysis of chloroplast membrane fractions shows that plastoglobules are a site of vitamin E accumulation in chloroplasts. Thus, in addition to their lipid storage function, we propose that plastoglobules are metabolically active, taking part in tocopherol synthesis and likely other pathways.

Footnotes

↵² The abbreviations used are: PAP, plastid lipid-associated protein; G-, C-, or YFP, green, cyan, or yellow fluorescent protein, respectively; At-, A. thaliana; PGL, plastoglobulin; AOS, allene oxide synthase; FBA, fructose-1,6-biphosphate aldolase; CAB, chlorophyll a/b-binding protein; TRITC, tetramethylrhodamine isothiocyanate; Tricine, N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine; MES, 4-morpholineethanesulfonic acid; TBS, Tris-buffered saline; HPLC, high performance liquid chromatography; SXD1, sucrose export-deficient 1 protein; MS, mass spectroscopy; MS/MS, tandem MS.
↵³ J. R. Austin, E. Frost, P. A. Vidi, F. Kessler, and L. A. Staehelin, submitted for publication.
↵^* This work was supported by the University of Neuchâtel and in part by the National Center for Competence in Research. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵ The on-line version of this article (available at http://www.jbc.org) contains supplemental Fig. 1.
- Received November 4, 2005.
- Revision received December 12, 2005.
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